Hum, from the speakers that is..
Mike
Friends,
Could I trouble you with a question that was probably answered long ago
when the A700 etc hit the market?
I have a plug in the phones socket with a lead to a Pioneer SA-5300
sterio amplifier driving 2 x Sharp CP-270E speakers.
The speakers have a rating of 4.OHMS (input impedance) and a Rated Input
of 25W.RMS
The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
more'.
I get a low level hum from the speakers which is just loud enough to be
intrusive.
Any suggestions as to what the problem may be; or even better how to
cure the problem without investing too much cash.
Thanks in advance.
--
/\/\ike Binks | On a RiscPC in Galloway
| Christian by persuasion
mailto: mi...@binks.clara.net | Fire Safety by profession
Patrick Herborn
In article <ant221646d07T&u...@binks.clara.net>
Mike <mi...@binks.clara.net> wrote:
> Friends,
Hi Mike!
> I have a plug in the phones socket with a lead to a Pioneer SA-5300
> sterio amplifier driving 2 x Sharp CP-270E speakers.
Is the amp earthed?
> The speakers have a rating of 4.OHMS (input impedance) and a Rated Input
> of 25W.RMS
OK, that's reasonably "standard" (although 8 ohms is more common).
> The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
> more'.
It's always good to have an amp that's more powerful than the speakers...
> I get a low level hum from the speakers which is just loud enough to be
> intrusive.
Sounds like you have an earthing problem. It could be an earth loop....
> Any suggestions as to what the problem may be; or even better how to
> cure the problem without investing too much cash.
You need to have ONE central earthing point; I suggest that this be in the
computer, although it could be in the amp. Remove the earth lead from the amp
and see whether this helps... (note that the amp will still be earthed
through the computer; it's not totally "floating")
> Thanks in advance.
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. I'm sure it's in the manual somewhere
R. Keeling
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote in article
<c61b...@nanobyte.demon.co.uk>...
DO NOT DO THIS!!!!!!!!!!!
Removing the Earth connection of the amplifier on the mains supply is can
be VERY
dangerous, the best method of breaking the earth loop is to disconnect the
earth at one
end of the audio connecting cable, if you get sound but no hum, you have
fixed it, however
if you get no sound it wasn't an earth loop in the first place.
If you break the earth connection in the mains lead the amp will not be
earthed when
the computer is disconnected, the amp casing could then become live under
fault conditions, this has been the course of many electrical accidents in
the music industry.
The noise could be H.F. interference from the computer in which case there
may not be anything
you can do is it a very low pitch hum or more of a hiss?
Rob Keeling
IT Technician - Queen Elizabeth`s Grammar School
(And holder of a HND in electronics)
Mike Enderby
In article <01bc3c31$5fc2d780$0100007f@localhost>, R. Keeling
<URL:mailto:rkee...@nether.net> wrote:
>
>
>
> Patrick Herborn <p...@nanobyte.demon.co.uk> wrote in article
> <c61b...@nanobyte.demon.co.uk>...
> > You need to have ONE central earthing point; I suggest that this be in
> the
> > computer, although it could be in the amp. Remove the earth lead from the
> amp
> > and see whether this helps... (note that the amp will still be earthed
> > through the computer; it's not totally "floating")
>
> DO NOT DO THIS!!!!!!!!!!!
Unless you *really* know what you are doing. I'd say that Pat does know what
he is doing.
> If you break the earth connection in the mains lead the amp will not be
> earthed when
> the computer is disconnected, the amp casing could then become live under
> fault conditions, this has been the course of many electrical accidents in
> the music industry.
If you are doing this it is vital to prevent this happening. This is
often done with scientific instrumentation as it can be the only way
to eliminate some sources of noise.
--
Mike Enderby
mi...@interpages.co.uk http://www.interpages.co.uk
Love your enemies: they'll go crazy trying to figure out what you're up to.
Philip Blundell
In article <01bc3c31$5fc2d780$0100007f@localhost>,
R. Keeling <rkee...@nether.net> wrote:
>If you break the earth connection in the mains lead the amp will not be
>earthed when
>the computer is disconnected, the amp casing could then become live under
>fault conditions, this has been the course of many electrical accidents in
>the music industry.
In any case, you do _not_ want your safety earth going through your
RiscPC's motherboard. In the best scenario, an electrical fault in
the amp would destroy the computer. In the worst one, it would
destroy the computer and still present a shock hazard.
I remember hearing a story in the early days of the RiscPC that they
were actually illegal for use in classrooms, because with a network
card fitted to certain case mouldings there was metalwork on the back
panel that _only_ earthed through the electronics, which melted during
the electrical-safety test and left the panel floating.
phil
--
^D
Patrick Herborn
In article <5hk5lo$l...@lyra.csx.cam.ac.uk>
pj...@thor.cam.ac.uk (Philip Blundell) wrote:
> In any case, you do _not_ want your safety earth going through your
> RiscPC's motherboard.
It's not the best solution. But if you were to disconnect the earth from the
RiscPC, letting the amp do the earthing then you'll have to contend with
increased RF emission from the RiscPC.
> In the best scenario, an electrical fault in the amp would destroy the
> computer. In the worst one, it would destroy the computer and still
> present a shock hazard.
Unlikely. The shield goes to a low impedance ground plane which connects to
the PSU by a pair of ground leads and the "conductive" case itself. You'de
blow the fuse in the amp's supply long before the computer was destroyed
(unless of course you've fitted the wrong fuse to the Amp's plug; and even if
that were the case, the amp will be fitted with a fuse of it's own)
> I remember hearing a story in the early days of the RiscPC that they
> were actually illegal for use in classrooms, because with a network
> card fitted to certain case mouldings there was metalwork on the back
> panel that _only_ earthed through the electronics, which melted during
> the electrical-safety test and left the panel floating.
And of course it will be earthed through the screen of the network cable
(back in those days it was 10Base2, which /must/ be earthed)
> phil
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. Help! I'm parked diagonally in a parallel universe.
Patrick Herborn
In article <01bc3c31$5fc2d780$0100007f@localhost>
"R. Keeling" <rkee...@nether.net> wrote:
> > You need to have ONE central earthing point; I suggest that this be in
> > the computer, although it could be in the amp. Remove the earth lead from
> > the amp and see whether this helps... (note that the amp will still be
> > earthed through the computer; it's not totally "floating")
>
> DO NOT DO THIS!!!!!!!!!!!
How so? My system has been thus for, oh, 15 years....
> Removing the Earth connection of the amplifier on the mains supply is can
> be VERY dangerous,
It can. If you're not careful.
> the best method of breaking the earth loop is to disconnect the earth at
> one end of the audio connecting cable,
That can help, yes, but it's a lot easier to remove the earth from a plug
than it is to hack about with the connecting leads, unless you're handy with
an iron of course. Anyone can use a screwdriver....
> if you get sound but no hum, you have fixed it, however if you get no sound
> it wasn't an earth loop in the first place.
You will always get sound. Whether there was an earth loop or not makes no
difference.
> If you break the earth connection in the mains lead the amp will not be
> earthed when the computer is disconnected, the amp casing could then become
> live under fault conditions,
Of course. But then I did credit the guy with enough sense to reconnect the
earth when the computer was no longer connected.
> this has been the course of many electrical accidents in the music
> industry.
Obviously someone forgot to label the equipment as not being earthed.
> The noise could be H.F. interference from the computer
This usually manifests itself as an LF modulated "crackle" rather than a hum.
> in which case there may not be anything you can do
Well if it's RF breakthough, you can shunt it to ground....
> is it a very low pitch hum or more of a hiss?
Pass, it ain't my equipment....
> Rob Keeling
Cheers,
Pat.
> (And holder of a HND in electronics)
(And holder of a BEng(Hons) in Electronic Engineering :-)
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. This Tagline is for sale. Call 1-800-TAG-THIS!
Philip Blundell
In article <55c79...@nanobyte.demon.co.uk>,
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>> I remember hearing a story in the early days of the RiscPC that they
>> were actually illegal for use in classrooms, because with a network
>> card fitted to certain case mouldings there was metalwork on the back
>> panel that _only_ earthed through the electronics, which melted during
>> the electrical-safety test and left the panel floating.
>
>And of course it will be earthed through the screen of the network cable
>(back in those days it was 10Base2, which /must/ be earthed)
Yes, but it's not obligatory for the network to be plugged in. And
the RiscPC wasn't released all _that_ long ago - 10baseT was certainly
around at the time. 1993 or whenever it was is scarcely the dark ages.
phil
--
^D
Mike Gilbert
In article <5hs06j$a...@lyra.csx.cam.ac.uk>, Philip Blundell
1995, actually. Unless, of course, the OS version postdates the
launch. RiscOS 3.5 is stamped 1994, 3.6 1995 and 3.7 1996. And I was
there, too, watching how easy it was for a little old lady to take
the lid off. Hmmm.
Mike
--
Mike Gilbert...an extra "i" keeps the junkmail away....
Michael Gilbert is currently appearing in 'An Evening With Dr Grace'
available through the Wessex Actors Company.
clemens
In article <c61b...@nanobyte.demon.co.uk>, Patrick Herborn wrote:
> In article <ant221646d07T&u...@binks.clara.net>
> Mike <mi...@binks.clara.net> wrote:
>
> > The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
> > more'.
>
> It's always good to have an amp that's more powerful than the speakers...
Ohh yes! So you are easily able to shoot your speakers!!! sounds funny...
Clemens
http://members.ping.at/clemens mailto:cle...@ping.at
_ _ _____
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/ \ | | | | | | __ / \
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Alan Adams
>In any case, you do _not_ want your safety earth going through your
>RiscPC's motherboard. In the best scenario, an electrical fault in
>the amp would destroy the computer. In the worst one, it would
>destroy the computer and still present a shock hazard.
>
You might also try ADDING earth connections. Start by plugging the
computer, monitor and amp into sockets very close together, for example on
a distribution block. This reduces the possibility of signals between the
earths of the systems. Then connect the systems together with a reasonably
thick stranded wire, such as one core from mains flex. (Ideally use the
earth one, so the colours don't get confusing.) The serial port turret
screw might be a good point to attach. Find a suitable part of the amp
which is earthed. Check with a meter if you are not sure.
Finally, if you still get hum, try disconnecting the screen of the signal
lead at one end. The whole idea of this is to prevent earth currents in
the screen, which are transformed into voltages in the inner conductor.
Somebody else suggested interference from the computer as a cause - it's
quite common. Try moving the amp and computer apart and see if the effect
changes. Rotating the amp can have an effect too.
You are using a line input? not a microphone input? If the input
sensitivity is tot=o high, you will get stray signals no matter what you
do. Using a large amp to drive relatively small speakers accentuates the
effect as well.
Good luck. Luck is usually what is needed in these situations.
--
Alan Adams
Dane Koekoek
In article <57209...@nanobyte.demon.co.uk>
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
> In article <01bc3c31$5fc2d780$0100007f@localhost>
> "R. Keeling" <rkee...@nether.net> wrote:
>
>
> > the best method of breaking the earth loop is to disconnect the earth at
> > one end of the audio connecting cable,
>
> That can help, yes, but it's a lot easier to remove the earth from a plug
> than it is to hack about with the connecting leads, unless you're handy
> with an iron of course. Anyone can use a screwdriver....
You obviously haven't seen my dad try to put a plug on a new
electric mower - it took him about an hour, and then he was petrified to
plug it in for fear of blowing the fuse in the fuse box and not knowing
what to do to fix it!!! That was years ago, though, as I get all those
jobs now and do them in 20 seconds flat. ;-)
> > (And holder of a HND in electronics)
>
> (And holder of a BEng(Hons) in Electronic Engineering :-)
Smartarse! ;-)
Cheers.
--
___ ___
| .//||\\___ da...@werewlf.demon.co.uk Why don't you call
| //_|| \\ http://www.werewlf.demon.co.uk/ Werewolf BBS? +44 181 289 6003
|// || \\_____________________* ANSI/33k6/24hr/8N1
Ian Clark
In comp.sys.acorn.hardware, clemens <cle...@ping.at> writes
>In article <c61b...@nanobyte.demon.co.uk>, Patrick Herborn wrote:
>
>> In article <ant221646d07T&u...@binks.clara.net>
>> Mike <mi...@binks.clara.net> wrote:
>>
>> > The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
>> > more'.
>>
>> It's always good to have an amp that's more powerful than the speakers...
>
>Ohh yes! So you are easily able to shoot your speakers!!! sounds funny...
>
because if your amp is less powerfull it will struggle to drive your
speakers, which can cause clipping of the signal, and wreck your
speakes. (So I'm told, but I am probably wrong.)
Ian, [8-)
--
Ian Clark, se9...@dmu.ac.uk
http://www.cms.dmu.ac.uk/~se96ic
Risc Tracker - Faster Action - DropBox - DeskMen
Nicholas Kitchener
Keith Goodier <ja...@argonet.co.uk> wrote:
>In article <AyUWrFA1...@cat1.demon.co.uk>, Ian Clark
><roo...@cat1.demon.co.uk> wrote:
>
>----snip----
>
>> It's a good idea to have an amp more powerfull than your speakers,
>> because if your amp is less powerfull it will struggle to drive your
>> speakers, which can cause clipping of the signal, and wreck your
>> speakes. (So I'm told, but I am probably wrong.)
I have a pair of Mission 734s- a friend's Technics AV amp stuggles to
drive them as a result there ain't much bass.. attach my Harmon Kardon
AVI200 (3x65W+2x25W RMS in surround or 2x80W RMS in stereo) and there is
copious amounts of bass as it has enough current to drive the bass cones
(they are 90dB sensitivity too..) ;) At my parents- the letterbox rattles
whilst watching Jurrasic Park.
[Mission home page: http://www.mission.co.uk]
>Those who really use their sound systems fairly hard - groups, discos
>and such - expect to hook up 200 watts of speaker to every 100w of amp.
>As long as the speakers are correctly matched for impedance the signal
>shouldn't suffer. What *will* cause a really nasty sound - guaranteed -
>is a sound system that can't handle the power put out by the amp.
Hmm but comparing a 10+KW sound system to a 100W system is not possible-
these large systems have loaded horns, active crossovers.. also you would
not run a system of that size at full pelt.
Clipping of the signal is when the sine wave peaks become flattened as
they hit the limits of the system- it is the sudden curve to square signal
that does the damage as the speaker cone is stopped rather than slowed
down. It really does not matter if your speakers are 100W speakers- a 20W
amp that is clipping WILL do damage to them.
It is better to run an amp that is say 150W/channel to a 80/100W speaker
as the extra power means the amp can contol the speaker cones with ease
rather than having to work hard to drive them (thus degrading your sound).
Sure- if you are stupid and shove the amp to 0dB att. then your going to
really damage you speakers..
To the point about 200W speakers- you'll find the current levels of these
amps way above those of the normal household amp (mine's max is 40Amps).
Anyway you can deafen youself with a 10W amp and a pair of horn loaded
speakers. I prefer a nice pair of Orrell 6000s with a 1KW RMS for the
tweeter (1Kg magnet here- bigger than the one in your bass bins!) alone-
remember the cups of water in jurassic park?
1W RMS = 4W PMPO = 2W MPO = ?W 'Peak Power'
Remember boys and girls: Only RMS counts.
Nick.
[ All this information is IIRC!! ]
+-
Nicholas Kitchener, Software Engineer, Logica UK
_kitchenern@logica.com____http://www.logica.com_
Please remove ANTISPAM on replying via email,
any junk mail will be bounced to your postmaster.
Defense:
Q: Doctor, did you say he was shot in the woods?
A: No, I said he was shot in the lumbar region.
Keith Goodier
----snip----
> It's a good idea to have an amp more powerfull than your speakers,
> because if your amp is less powerfull it will struggle to drive your
> speakers, which can cause clipping of the signal, and wreck your
> speakes. (So I'm told, but I am probably wrong.)
Those who really use their sound systems fairly hard - groups, discos
and such - expect to hook up 200 watts of speaker to every 100w of amp.
As long as the speakers are correctly matched for impedance the signal
shouldn't suffer. What *will* cause a really nasty sound - guaranteed -
is a sound system that can't handle the power put out by the amp.
--
|/
|\eith
ja...@argonet.co.uk
clemens
In article <AyUWrFA1...@cat1.demon.co.uk>, Ian Clark wrote:
> In comp.sys.acorn.hardware, clemens <cle...@ping.at> writes
> >In article <c61b...@nanobyte.demon.co.uk>, Patrick Herborn wrote:
> >
> >> In article <ant221646d07T&u...@binks.clara.net>
> >> Mike <mi...@binks.clara.net> wrote:
> >>
> >> > The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
> >> > more'.
> >>
> >> It's always good to have an amp that's more powerful than the speakers...
> >
> >Ohh yes! So you are easily able to shoot your speakers!!! sounds funny...
> >
> It's a good idea to have an amp more powerfull than your speakers,
> because if your amp is less powerfull it will struggle to drive your
> speakers, which can cause clipping of the signal, and wreck your
> speakes. (So I'm told, but I am probably wrong.)
Definitly Not! Your amp will only care about the ipedance (ohms) of your
speakers - not the power. if your amp gives an output power of 100W and your
speakers have a maximum! power of 120W (or even 100W), then everything will be
OK. If it is vice versa, then you hve to be carefully, not to play to loudly.
clipping and demaging our speakers have the same reasons.
discribing this in english is a little bit hard for me, but i will try if you
want me to.
Clemens
http://members.ping.at/clemens mailto:cle...@ping.at
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Ian Bannister
In article <5i0lbe$m...@romeo.logica.co.uk>, Nicholas Kitchener
<kitch...@logica.ANTISPAM.com> wrote:
>
<snipped discussion about amp power & speaker ratings>
>
> Clipping of the signal is when the sine wave peaks become flattened as
> they hit the limits of the system- it is the sudden curve to square signal
> that does the damage as the speaker cone is stopped rather than slowed
> down.
a speaker during its normal operation that would try to stop the cone. Even
try and reverse it immediately in some cases. This is normal when any audio
signal is applied. Signals like clipped waveforms which have large high
frequency components will have these directed to the tweeters. It is the
excess power here which can cause the damage.
> It really does not matter if your speakers are 100W speakers- a 20W
> amp that is clipping WILL do damage to them.
Maybe, it depends on the actual power handling of the HF drivers. Many are
much more efficient than bass drivers and may not have the actual power
rating to withstand it. The way to damage a bass unit is to apply a very low
frequency sine wave.
--
Ian Bannister ___________________________
||---------------------/ \
|| < banni...@argonet.co.uk >
||---------------------\___________________________/
Thu,03 Apr 1997.22:14:42
David Higton
In message <AyUWrFA1...@cat1.demon.co.uk>, Ian Clark
(roo...@cat1.demon.co.uk) wrote:
>>Ohh yes! So you are easily able to shoot your speakers!!! sounds funny...
>>
>It's a good idea to have an amp more powerfull than your speakers,
>because if your amp is less powerfull it will struggle to drive your
>speakers, which can cause clipping of the signal, and wreck your
>speakes. (So I'm told, but I am probably wrong.)
produced. These will mostly be in the passband of the HF driver, which is
rated for much lower power than the LF driver. It's entirely possible
for the HF driver to be overdriven as a result, and melt the glue between
the coil and diaphragm, or even burn out the coil. The thermal time
constant of the HF driver is also much shorter than that of the LF driver,
another factor which makes it easier to burn it out.
An amplifier of higher power rating than the speakers is OK so long as you
don't overdissipate the speakers. Under these circumstances it will sound
cleaner than a lower-power amplifier which is just reaching clip point at
the same power. Of course, if you just keep on turning up the wick, you'll
find it easier to kill speakers with a more powerful amplifier.
Dave
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David Higton
In message <57209...@nanobyte.demon.co.uk>, Patrick Herborn
(p...@nanobyte.demon.co.uk) wrote:
>> > You need to have ONE central earthing point; I suggest that this be in
>> > the computer, although it could be in the amp. Remove the earth lead from
>> > the amp and see whether this helps... (note that the amp will still be
>> > earthed through the computer; it's not totally "floating")
>>
>> DO NOT DO THIS!!!!!!!!!!!
>
>How so? My system has been thus for, oh, 15 years....
>
>> Removing the Earth connection of the amplifier on the mains supply is can
>> be VERY dangerous,
>
>It can. If you're not careful.
fault develops, rather than whether you're being careful. Also, bear in
mind that, if a mains fault to earth develops, you're going to do a lot
of damage to the 0V system of the computer. This is expensive to fix!
The best idea I've come across is a parallel combination of a resistor and
two diodes. The two diodes must be in opposite directions, and must also
be of a heavy "pellet" construction. This is of crucial importance to the
safety of the system; the heavy construction ensures that the bonding
wires won't blow out, and the pellet construction gives no thin internal
wire to blow. Therefore, if a large fault current flows, the diodes will
go short circuit, thus maintaining protection to you and the equipment
surrounding it.
This network goes in series with the earth lead of the amplifier to the mains
plug. Use about 100 ohms for the resistor. Years ago I used to use
1N5401 diodes; there may be more modern devices suitable. Don't use
anything as small as 1N4001 series; these cannot be considered safe for
the job.
The idea of operation is that, up to about 0.4V, hardly any current flows
through the network. This ensures that the earth loop is, to all reasonable
hum currents, broken, but the integrity of the signal earth is maintained.
The hum problem is now solved.
If, however, a mains fault to earth develops, then the diodes start to
conduct. It requires a very high current indeed to develop a voltage of
over 2V across suitably heavy diodes. So your personal protection is
maintained.
>> (And holder of a HND in electronics)
>
>(And holder of a BEng(Hons) in Electronic Engineering :-)
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>
>> The speakers have a rating of 4.OHMS (input impedance) and a Rated
>> Input of 25W.RMS
> OK, that's reasonably "standard" (although 8 ohms is more common).
>> The amplifier is rated at 120W and has a warning 'Speakers 4 ohms or
>> more'.
> It's always good to have an amp that's more powerful than the
> speakers...
Sorry, why?
-Ian
--
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Yipeee! the `Better than Squeezy's` Sig machine works!!!
Ian Clark
In comp.sys.acorn.hardware, Nicholas Kitchener <kitch...@logica.ANTISP
AM.com> writes>><roo...@cat1.demon.co.uk> wrote:
>>
>>----snip----
>>
>>> It's a good idea to have an amp more powerfull than your speakers,
>>> because if your amp is less powerfull it will struggle to drive your
>>> speakers, which can cause clipping of the signal, and wreck your
>>> speakes. (So I'm told, but I am probably wrong.)
>
>drive them as a result there ain't much bass.. attach my Harmon Kardon
>AVI200 (3x65W+2x25W RMS in surround or 2x80W RMS in stereo) and there is
>copious amounts of bass as it has enough current to drive the bass cones
>(they are 90dB sensitivity too..) ;) At my parents- the letterbox rattles
>whilst watching Jurrasic Park.
>
Keyboard buffer!!) but I am only a poor uni student though. Mind you the
Wharfdale Diamond IVs I've got don't do too bad. A mate of mines just
got a pair of Keff Coda 8s which are v.nice.
<Ob Acorn>
They don't sound too bad connected to the RPC either. (Now all we need
is a /fast/ port of Quake.....)
Nicholas Kitchener
Ian Bannister <banni...@argonet.co.uk> wrote:
>In article <5i0lbe$m...@romeo.logica.co.uk>, Nicholas Kitchener
><kitch...@logica.ANTISPAM.com> wrote:
>>
><snipped discussion about amp power & speaker ratings>
>>
>> Clipping of the signal is when the sine wave peaks become flattened as
>> they hit the limits of the system- it is the sudden curve to square signal
>> that does the damage as the speaker cone is stopped rather than slowed
>> down.
> This does not make sense. It is quite possible that a signal is applied to
>a speaker during its normal operation that would try to stop the cone. Even
>try and reverse it immediately in some cases. This is normal when any audio
>signal is applied. Signals like clipped waveforms which have large high
>frequency components will have these directed to the tweeters. It is the
>excess power here which can cause the damage.
I stand corrected- thanks.
>> It really does not matter if your speakers are 100W speakers- a 20W
>> amp that is clipping WILL do damage to them.
> Maybe, it depends on the actual power handling of the HF drivers. Many are
>much more efficient than bass drivers and may not have the actual power
>rating to withstand it. The way to damage a bass unit is to apply a very low
>frequency sine wave.
Hmmm water cooled speakers..
Nick.
Fons Adriaensen
In article <na.f034474775.a...@argonet.co.uk> Ian Bannister <banni...@argonet.co.uk> writes:
> <snip>
>
> The way to damage a bass unit is to apply a very low
> frequency sine wave.
Many power amps today (and nearly all the very high power models) are DC coupled at
the output. Normally, the output is DC free because the input signal is DC free.
But when you drive such an amp into clipping using an assymetrical signal (as most
music signals are), it will produce significant VLF or DC energy, and this could
damage or destroy the bass unit.
--
Fons Adriaensen
ALCATEL TELECOM
David Higton
In message <5i2e2a$f...@romeo.logica.co.uk>, Nicholas Kitchener
(kitch...@logica.com) wrote:
>Hmmm water cooled speakers..
Not common, but Ferrofluid is sometimes used to assist cooling.
David Higton
In message <5i0lbe$m...@romeo.logica.co.uk>, Nicholas Kitchener
(kitch...@logica.com) wrote:
> 1W RMS = 4W PMPO = 2W MPO = ?W 'Peak Power'
>
>Remember boys and girls: Only RMS counts.
times amps RMS gives watts RMS. This is NOT the case. (I'm assuming a
purely resistive situation here.) Volts RMS times amps RMS gives
watts AVERAGE (in a resistive load).
Whilst it is possible to calculate the RMS value of the power delivered
to a load, it's of no use that I know of. What we normally care about is
the heating effect - and that is the average power.
David Higton
In message <na.271a10477...@argonet.co.uk>, Keith Goodier
(ja...@argonet.co.uk) wrote:
>Those who really use their sound systems fairly hard - groups, discos
>and such - expect to hook up 200 watts of speaker to every 100w of amp.
rated higher than the amps, they are still safe despite the high level
of harmonics, as I said in the last msg.
>What *will* cause a really nasty sound - guaranteed - is a sound system
>that can't handle the power put out by the amp.
non-linear above their rated power output[1]. This means that they sound the
same, but they don't last long (seconds at most). So long as you keep these
over-the-rating peaks short, and leave long periods in between for the voice
coil to cool down, the scound continues to be clean. Short and long are
defined relative to the thermal time constant of the voice coil assembly.
Amplifiers, OTOH, distort heavily as soon as they are over the limit.
[1] At low frequencies, where the cone excursions are large, they are
non-linear (3% distortion is quite normal for a *good* speaker), and
the non-linearity, and hence the proportion of distortion products,
increase with level. However, this isn't a cliff-edge phenomenon,
unlike overloading an amplifier.
Patrick Herborn
In article <970405...@arcade.demon.co.uk>
daveh...@arcade.demon.co.uk (David Higton) wrote:
> >Those who really use their sound systems fairly hard - groups, discos
> >and such - expect to hook up 200 watts of speaker to every 100w of amp.
>
> That's because they routinely overdrive their amps.
Which is a _really_daft_thing_to_do
> With speakers rated higher than the amps, they are still safe despite the
> high level of harmonics, as I said in the last msg.
Absolute rubbish! Speakers are designed to handle a certain spectral power
density curve, that which is common to most forms of audio material that they
are likely to be asked to reproduce. When an amp is driven into clipping the
power density at the top end is much higher than usual and the result is that
the HF transducers blow up. A speaker system rated at 100W RMS (or more
correctly 20dBW) will have an HF transducer rated at abot 10W RMS, the reason
being that only 6% of the spectral power is present in the range of the
spectrum that the HF transducer is being asked to handle. Given the shift in
the power density curve, the HF transducer will be fed with much more than
10W RMS and will consequently fail.
> >What *will* cause a really nasty sound - guaranteed - is a sound system
> >that can't handle the power put out by the amp.
>
> Funnily enough, this is not the case.
Agreed. It is quite possible to feed 1kW into a 1W HF unit and expect only
very little extra distortion as a result. The 'catch' is that if you do this
for more than a few ms at a time, your HF unit will die.
> Loudspeakers don't suddenly become non-linear above their rated power
> output.
They can do, if the cone starts bottoming or the surround / spider reach the
limit of their compliance. But this is not often the case. Note that driving
a 400W bass transducer with just 1W RMS can cause catastrophic failure of the
transducer. It's all to do with the spectral power density curve that the
transducer is designed for. Loudspeakers are immensely complex
electro-mechano-acoustic systems and the interaction of the three separated
"circuits" is so complex that it cannot be modelled accurately.
> This means that they sound the same, but they don't last long (seconds at
> most).
If you are overdriving them constantly, this will certainly be the case.
However if you are driving them with an RMS power equal to or less than their
RMS rating, no damage should result. To make this point clearer, it would be
quite acceptable to drive a 1W transducer with 0.99W for 99% of the time
and 10W for 1% of the time.
> So long as you keep these over-the-rating peaks short, and leave
> long periods in between for the voice coil to cool down, the sound
> continues to be clean.
That is correct. Most transducers do not object to being 'overdriven'.
> Short and long are defined relative to the thermal time constant of the
> voice coil assembly.
You must also take into account the mechanical stress which results from
overdriving... mechanical failure could result, even if thermal failure
doesn't.
> Amplifiers, OTOH, distort heavily as soon as they are over the limit.
That depends on the dynamic headroom of the particular amplifier. While it is
true to say that in all cases if you try to exceed the RMS power output of
the amplifier then distortion will result, it is important to note that RMS
power is a way of expressing the power output in terms of the steady state
(DC) equivalent power.
Music is dynamic in nature, and as a result expressing it's RMS value is
always very difficult. Typical pop music has a 16dB gap between the peaks and
the RMS level. Heavy metal tends to have a lower gap, whereas classical has a
much larger gap.
The power rating you see on an amplifier refers to the power (typically at
1kHz) that it can deliver into an 'equivalent' load and tells you virtually
nothing about it's dynamic characteristics. That's where dynamic headroom and
transient IMD come in.
It was noted above that typical pop music had a 16 dB gap between peaks and
the RMS level. If your amplifier has no dynamic headroom then you must ensure
that the peaks fall within the RMS power rating of the amplifier, if you wish
to avoid distortion. If your amplifier has 16dB dynamic headroom then you can
wind up the volume another 16 dB before you encouter distortion; note that
BOTH units have the same RMS pwer rating... the latter will sound almost
twice as loud, though. In the latter case the RMS power of the music being
(re)played is using almost 100% of the amplifier's power, but it is able to
go beyond 100% (up to 4000%) for short periods of time (transients).
To further complicate the issue, the loudspeaker system presents a time
variant impedance to the amplifier. One millisecond it might be 8 ohms with
zero phase angle, the next it might be 6 ohms with a +43 degree phase angle,
the next it might be 136 ohms with a -90 degree phase angle. This is the true
test of an amplifier, how well it can cope with this constantly changing
impedance. Two amplifiers with the same power rating, the same dynamic
headroom and the same frequency response when measured in the lab, can (and
do) sound completely different in the 'real world' as a result. The transient
IMD figure may give you a clue as to how well an amp will work, but there is
only one way to know for sure.... LISTEN TO IT :-)
> [1] At low frequencies, where the cone excursions are large, they are
> non-linear (3% distortion is quite normal for a *good* speaker),
Fortunately, LF distortion is imperceptible by humans below about 10% anyway,
so this is not a great worry... in the midrange things get a bit more
critical where even 0.1% is quite perceptible.
> and the non-linearity, and hence the proportion of distortion products,
> increase with level.
That is correct. But it is also worth noting that the air itself becomes
non-linear at 130dB. This has been a long term problem with horn designs. Now
I'm sure that Messrs Thiele, Small and Klipsh would have some interesting
insights in this area, but I doubt that they read CSA.H..... :-)
> However, this isn't a cliff-edge phenomenon, unlike overloading an
> amplifier.
If you hear it at all, that is :-)
> Dave
Cheers,
Pat.
ob: Acorns don't tend to produce hum.... well none of mine have....
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. President/VicePresident is undefined. Cannot divide by zero.
Patrick Herborn
> >Hmmm water cooled speakers..
>
> Not common,
SOmetimes used to cool the magnet assembles, but very rare!
> but Ferrofluid is sometimes used to assist cooling.
Yep, mostly on HF transducers where the voicecoils have to be small &
lightweight. But then there's nothing quite like an ionostat :-) (well,
forgetting about the ozone it produces, anyway...)
> Dave
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. I'm not nearly as think as you confused I am.
Patrick Herborn
> > 1W RMS = 4W PMPO = 2W MPO = ?W 'Peak Power'
> >
> >Remember boys and girls: Only RMS counts.
>
> Just an academic point here: most people wrongly believe that volts RMS
> times amps RMS gives watts RMS. This is NOT the case.
Yes, the phase angle does play a rather important role :-)
If your phase angle is 90 degrees (+ or -) then your power is zero, no matter
how large your current or voltage.
> (I'm assuming a purely resistive situation here.)
RMS power always had me rather confused anyway... RMS voltage, fine. RMS
current, fine. RMS power, hmmm... After all RMS was invented as a means of
working out the equivalent DC voltage (or current) that would be needed to
produce the same heating effect as a particular AC voltage (or current)
waveform. And fair enough, instantaneous power is proportional to the square
of the voltage (or current), so to average the power you do need to square
the voltage (or current), and you do need to root the result to get back a
meaningful voltage (or current), but for power..... hmmm.... no need to
square as far as I can see...
> Volts RMS times amps RMS gives watts AVERAGE (in a resistive load).
That's right...
> Whilst it is possible to calculate the RMS value of the power delivered
> to a load, it's of no use that I know of.
Calculating the RMS power seems rather odd to me. I just take RMS, when
applied to power, to mean average, it makes more sense that way :-) OK, it's
a misnomer, but then so is a 1.5 volt battery.....
> What we normally care about is the heating effect - and that is the average
> power.
Yep. Agreed. But I suppose that people thought that if we say that
Volts (RMS) * Amps (RMS) * cos(phi) = Power (RMS)
it would be clear how the power figure was arrived at (ie just using the RMS
postfix cosmetically rather than it's true sense).
> Dave
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. If this were an actual tagline, it would be funny.
Andrew Buckingham
On Thu Apr 3 Nicholas Kitchener wrote about Hum, from the speakers that is..:-
NK> Clipping of the signal is when the sine wave peaks become flattened
NK> as they hit the limits of the system- it is the sudden curve to
NK> square signal that does the damage as the speaker cone is stopped
NK> rather than slowed down. It really does not matter if your speakers
NK> are 100W speakers- a 20W amp that is clipping WILL do damage to them.
Oh s***!
About two years ago I acquired a rather nice pair of 100W-ish Technics
speakers... Somewhat wasted on my puny 10W Alba amplifier! (Hey, I'm a poor
student, OK? ;-)
Playing the ol' Dire Straits at full volume does tend to saturate the output
during louder moments, but I'd always assumed that 100W speakers could never
be damaged by a 10W signal. (hope my electronics teacher doesn't read this
newsgroup).
Cheers,
_________.________ ____________________________________________________
/| . _ _ \ /
/ | /| // \ \/ Andrew D. Buckingham StrongARM Risc PC
/--|/ |//__/ / And...@arcade.demon.co.uk 38MB / 2.5GB
_____/ |________/_______________________________________________________
S Pampling
In article <na.f034474775.a...@argonet.co.uk>, Ian Bannister
<banni...@argonet.co.uk> wrote:
> > It really does not matter if your speakers are 100W speakers- a 20W
> Maybe, it depends on the actual power handling of the HF drivers. Many
> are much more efficient than bass drivers and may not have the actual
> power rating to withstand it. The way to damage a bass unit is to apply a
> very low frequency sine wave.
I found Pink Floyd's Saucerful of secrets to be quite effective in that
respect. Certainly wrecked a few speakers in high street stores :-)
SteveP
--
steve.p...@argonet.co.uk or ca...@argonet.co.uk for CAMRA items
ZFC A (still)
* Campaign for Real Ale, Warwickshire Area Organiser *
* "Cracking Toast Grommit" - Wallace *
* "Cracking beer Grommit" - Wallace's brother *
Ian Molton
Ian Clark <roo...@cat1.demon.co.uk> wrote:
> It's a good idea to have an amp more powerfull than your speakers,
> because if your amp is less powerfull it will struggle to drive your
> speakers, which can cause clipping of the signal, and wreck your
> speakes. (So I'm told, but I am probably wrong.)
very wrong - what do you think quiet bits in music do? drive your amp at
maximum power?
No comments about class A etc, please.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Stoke me a clipper - I'll be back for ... Christmas
Nicholas Kitchener
Ian Wallace <i...@cloudnine.demon.co.uk> wrote:
>In article <970407...@arcade.demon.co.uk>
> And...@arcade.demon.co.uk (Andrew Buckingham) wrote:
>
>>> Clipping of the signal is when the sine wave peaks become flattened
This point- I have been corrected- it's the harmonics that rip your HF
units to bits.
>>> ... It really does not matter if your speakers
>>> are 100W speakers- a 20W amp that is clipping WILL do damage to them.
>> Oh s***!
>> About two years ago I acquired a rather nice pair of 100W-ish Technics
>> speakers... Somewhat wasted on my puny 10W Alba amplifier! (Hey, I'm a
>> poor student, OK? ;-)
>Technics - Nice. Alba - Poo.
Um- I got my Speakers, Amp, Laserdisk player, Video .. on my year out.. Well
you've got to spend all that tax free dosh on something!
>> Playing the ol' Dire Straits at full volume does tend to saturate the
>> output during louder moments, but I'd always assumed that 100W speakers
>> could never be damaged by a 10W signal. (hope my electronics teacher
>> doesn't read this newsgroup).
>At my local school they've just bought a new PA system, and very nice it
>is too. However, the amplifier is rated at 900W (450W a side at 4ohms IIRC)
>but the speakers (4 ohms I believe) are rated at 350 a piece. Is this good
>or is my system in my room (25W amp, 80W each speakers) the best way round?
I'd say as it helps having an amp with a bit of grunt connected to speakers
helps as the amp always keeps control of the speaker- but it has a little
downside as you can damage your speakers by overloading them (normal amps
will cutout before the speaker gets it- mine has a cut out for this based
on the current being drawn). If you start getting into the Audiophile amps
(500ukp+) you may find that you don't get these features.. as it degrades
the sound.
Just a quick point re: amps & speakers- it doesn't matter how good/bad your
amp or speakers are if they have some 24guage bell cable joining them.. the
standard cost of interconnections should be about 10%-15% of total system
cost. Also bi/tri-wiring the speakers does wonders.. got bi-wired QUEDos
(the purple stuff) and some good interconnects- the difference blew me away.
Please- forget the bell cable!
Mind you- power isn't everything.. some of the most expensive amps are the
as low powered as 10watts.. but I couldn't afford the 43,000ukp price tag
nor any other components that could match it.
I think this is getting out of the relms of c.s.a.h..
Ian Wallace
>> Clipping of the signal is when the sine wave peaks become flattened
>> as they hit the limits of the system- it is the sudden curve to
>> square signal that does the damage as the speaker cone is stopped
>> rather than slowed down. It really does not matter if your speakers
>> are 100W speakers- a 20W amp that is clipping WILL do damage to them.
> Oh s***!
> About two years ago I acquired a rather nice pair of 100W-ish Technics
> speakers... Somewhat wasted on my puny 10W Alba amplifier! (Hey, I'm a
> poor student, OK? ;-)
Technics - Nice. Alba - Poo.
> Playing the ol' Dire Straits at full volume does tend to saturate the
> output during louder moments, but I'd always assumed that 100W speakers
> could never be damaged by a 10W signal. (hope my electronics teacher
> doesn't read this newsgroup).
At my local school they've just bought a new PA system, and very nice it
is too. However, the amplifier is rated at 900W (450W a side at 4ohms IIRC)
but the speakers (4 ohms I believe) are rated at 350 a piece. Is this good
or is my system in my room (25W amp, 80W each speakers) the best way round?
--
Ian Wallace (i...@cloudnine.demon.co.uk)
www.cloudnine.demon.co.uk
"This Earth requires more study,
It seems to weird to be destroyed"
Matthew Burke
In article <258a...@cloudnine.demon.co.uk>, Ian Wallace
<i...@cloudnine.demon.co.uk> wrote:
> >> Clipping of the signal is when the sine wave peaks become flattened
> >> as they hit the limits of the system- it is the sudden curve to
> >> square signal that does the damage as the speaker cone is stopped
> >> rather than slowed down. It really does not matter if your speakers
> >> are 100W speakers- a 20W amp that is clipping WILL do damage to them.
> > Oh s***!
> > About two years ago I acquired a rather nice pair of 100W-ish Technics
> > speakers... Somewhat wasted on my puny 10W Alba amplifier! (Hey, I'm a
> > poor student, OK? ;-)
> Technics - Nice. Alba - Poo.
Very, Very simple solution to this, even for a poor student (eg. me with my
poor student A3010...)
1. Go to the Littlewoods catalogue
2. Order that nice shining 1440W Aiwa NSX-999 with 38wks intrest free cred.
3. Check the delivery (they /always/ f**k up!)
3. Hook up your 200W guitar amp to the super-woofer socket
4. Enjoy the great sound of /2000W PMPO/ music power
aaaahhhhhh! BOOM! BOOM! BOOM!
5. Party! Party! Party! Party! Party! Party! Party! Party! Par(hic)ty!
--
___________________________________________________________
| ___ \
| |\ /| |__> /======================\ \
| | \ / | | \ < m.b...@argonet.co.uk > >
| | \/ |ATTHEW |__/URKE \======================/ /
|____________________________________________________________/
... A wise man once said.... I don't know...
Ian Clark
In comp.sys.acorn.hardware, Ian Molton <ha...@zetnet.co.uk> writes
>Ian Clark <roo...@cat1.demon.co.uk> wrote:
>
>> It's a good idea to have an amp more powerfull than your speakers,
>> because if your amp is less powerfull it will struggle to drive your
>> speakers, which can cause clipping of the signal, and wreck your
>> speakes. (So I'm told, but I am probably wrong.)
>
>very wrong - what do you think quiet bits in music do? drive your amp at
>maximum power?
>
to drive the speakers with the loud bits of music, and cause clipping,
which wrecks your speakers.
In the instruction book of my friends Keff Coda 8s it says that you
should not drive them with an underpowered amp.
>No comments about class A etc, please.
>
Isn't class A always driven at full pelt. ;-)))
>-Ian
>
Erm, ditto.
--
Ian Clark, se9...@dmu.ac.uk
http://www.cms.dmu.ac.uk/~se96ic
"Cat... Are you drilling?"
Ian Wallace
In article <n774...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
>> It's a good idea to have an amp more powerfull than your speakers,
>> because if your amp is less powerfull it will struggle to drive your
>> speakers, which can cause clipping of the signal, and wreck your
>> speakes. (So I'm told, but I am probably wrong.)
> very wrong - what do you think quiet bits in music do? drive your amp at
> maximum power?
Are you sure??
As someone pointed out, when an amp clips, sound distorts (I think someone
said that the wave turns square, which the speaker finds hard to cope with)
which damages your speakers.
Therefore, if you want to drive your 200W speakers at 200W, you buy a
300W amp and turn down the volume a bit, giving you headroom. You may
blow your speakers, but only if you set the volume too high. Where as if
you try to run a higher powered amp at the same wolume, then the amp
will clip, damaging the speakers.
> No comments about class A etc, please.
*sigh* Technics...... ;-)
Glenn Richards
In article <n774...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
> > It's a good idea to have an amp more powerfull than your speakers,
> > because if your amp is less powerfull it will struggle to drive your
> > speakers, which can cause clipping of the signal, and wreck your
> > speakes. (So I'm told, but I am probably wrong.)
>
> very wrong - what do you think quiet bits in music do? drive your amp at
> maximum power?
Only if you have a Class A amp... :-)
But the original point is correct, it's easier to blow a 100W pair of
speakers with a 50W amp than a 200W amp, as the 50W amp would overload and
go into distortion, frying your tweeters!
Although if you're overloading a 50Wpc amp then either you have very
inefficient speakers or you need your hearing checked!
--
Glenn Richards [ squi...@2squirrels.argonet.co.uk ]
Squirrel Solutions [ rich...@2squirrels.arcticbb.demon.co.uk ]
Acorn comms/networking specialists [ Fidonet#2:253/401.0 ]
Anti-Spam: Remove 3 - 1 squirrels to reply
Ian Molton
Ian Clark <roo...@cat1.demon.co.uk> wrote:
>>> It's a good idea to have an amp more powerfull than your speakers,
>>> because if your amp is less powerfull it will struggle to drive your
>>> speakers, which can cause clipping of the signal, and wreck your
>>> speakes. (So I'm told, but I am probably wrong.)
>> very wrong - what do you think quiet bits in music do? drive your amp
>> at maximum power?
> No, I ment if you turn an underpowered amp up too high it will struggle
> to drive the speakers with the loud bits of music, and cause clipping,
> which wrecks your speakers.
No - clipping is caused when the input to your amp is driven too hard.
It is nothing to do with the speakers - not, that is, till you turn it up
REALLY loud
> In the instruction book of my friends Keff Coda 8s it says that you
> should not drive them with an underpowered amp.
I suspect they might be talking about impedance - which has nothing to do
with power.
>> No comments about class A etc, please.
> Isn't class A always driven at full pelt. ;-)))
The amp, yes - the speakers? no.
>> -Ian
> Erm, ditto.
Ditto again <g>
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Smeg... I forgot to ask if there were any curry houses in Dallas.......
Ian Molton
Ian Wallace <i...@cloudnine.demon.co.uk> wrote:
> Are you sure?? As someone pointed out, when an amp clips, sound distorts
> (I think someone said that the wave turns square, which the speaker
> finds hard to cope with) which damages your speakers. Therefore, if you
> want to drive your 200W speakers at 200W, you buy a 300W amp and turn
> down the volume a bit, giving you headroom. You may blow your speakers,
> but only if you set the volume too high. Where as if you try to run a
> higher powered amp at the same wolume, then the amp will clip, damaging
> the speakers.
Well, that is *bollocks* The amp clips when the *input* level is too high
not the *output* level. If your audio equipment is good, this will never
happen. granted, clipping doesn't do a *huge* ammount of good, but it's
nowhere near as bad as frying your expensive speakers.
>> No comments about class A etc, please.
> *sigh* Technics...... ;-)
<evil grin> QUAD.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
How can one little piece of insulated wire bring so much happiness??
Ian Bannister
In article <n7AF...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
>
> Ian Wallace <i...@cloudnine.demon.co.uk> wrote:
>
> > Are you sure?? As someone pointed out, when an amp clips, sound distorts
> > (I think someone said that the wave turns square, which the speaker
> > finds hard to cope with) which damages your speakers. Therefore, if you
> > want to drive your 200W speakers at 200W, you buy a 300W amp and turn
> > down the volume a bit, giving you headroom. You may blow your speakers,
> > but only if you set the volume too high. Where as if you try to run a
> > higher powered amp at the same wolume, then the amp will clip, damaging
> > the speakers.
>
> Well, that is *bollocks*
> The amp clips when the *input* level is too high
> not the *output* level. If your audio equipment is good, this will never
> happen. granted, clipping doesn't do a *huge* ammount of good, but it's
> nowhere near as bad as frying your expensive speakers.
No amplifier that clips on its input stages before the output does is worth
calling a hifi amp. How can an input running at a few 100s of millivolts run
out of supply? The amp clips when there is not enough volts to drive the
speakers any further. This is taken into account by the design so a 60W amp
would need around 65V to drive into 8ohms. The input stages would use
typically +/-15V (30V) so would be in no danger of clipping.
If you are running with low volume settings but still getting high output
then this is a sign of an overloaded input. But if its a decent amp and
you're not running something like a CD into the disc (phono) input then any
normal input levels should be OK.
--
Ian Bannister ___________________________
||---------------------/ \
|| < banni...@argonet.co.uk >
||---------------------\___________________________/
Tue,15 Apr 1997.21:58:28
Philip Blundell
In article <19970415....@mightoak.demon.co.uk>,
Bob Latham <b...@mightoak.demon.co.uk> wrote:
>the HF units in danger. If you talk to people in hifi shops they will
>tell you - The most common way to blow a speaker *by far* is too small
>an amp clipping and blowing the HF drive unit. As I said before. When
>the wave squares up, huge amounts of energy are thrown at the HF driver
>by the crossover. Remember, a 100 watt speaker may only have a 5 watt
>tweeter.
Yeah, quite. I've seen an upsetting number of speakers that have had
their tweeters taken out like this - and in a surprising number of
cases, the owners hadn't actually _noticed_ that they weren't getting
any sound from one or both tweeters.
I know a guy who used to use his hifi for (mercifully infrequent)
parties. Both his amp and speakers were towards the high-power-rating
end of normal domestic stuff - sadly, he also fancied himself as a DJ,
and had a mixing desk connected up to the amplifier's line inputs.
The presets on said desk were totally screwed up, and he was driving
the inputs of the amp about five times as hard as he ought to have
been - this, probably combined with the fact that he kept turning the
volume knob up too high (well past the point at which the amplifier
couldn't actually provide any more output) meant that he tended to
blow up some or all of his kit every time. He only usually noticed
that anything was wrong when the amp got so hot that it shut down, or
the protection fuses blew, by which time his speakers were invariably
wrecked.
phil
--
^D
Glenn Richards
> not the *output* level. If your audio equipment is good, this will never
> happen. granted, clipping doesn't do a *huge* ammount of good, but it's
> nowhere near as bad as frying your expensive speakers.
No, an amp will clip when the input /or/ output level is too high, although
it happens in different ways. When the output clips (assuming we're talking
about an audio amplifier) it's usually because the speakers hit their
end-stops, creating an inductive short across the output, effectively
sending a large DC current back into the system. The effect of this is a
load "crack" sound through the speakers...it doesn't do them any good - I
speak from experience!
Glenn
Philip Blundell
In article <na.db62dd477b....@argonet.co.uk>,
Glenn Richards <squi...@argonet.co.uk> wrote:
>In article <n7AF...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
>> Well, that is *bollocks* The amp clips when the *input* level is too high
>> not the *output* level. If your audio equipment is good, this will never
>> happen. granted, clipping doesn't do a *huge* ammount of good, but it's
>> nowhere near as bad as frying your expensive speakers.
>
>No, an amp will clip when the input /or/ output level is too high, although
>it happens in different ways. When the output clips (assuming we're talking
>about an audio amplifier) it's usually because the speakers hit their
>end-stops, creating an inductive short across the output, effectively
>sending a large DC current back into the system. The effect of this is a
>load "crack" sound through the speakers...it doesn't do them any good - I
>speak from experience!
No, no. That's not the amplifier clipping - the speaker coils
bottoming out against the end-stops is a different problem, though
you're quite right that it's not good news either. However, it _is_
very immediately audible, and so you get plenty of warning that
something is wrong. Clipping is a bit more insidious, because it's
possible to damage your speakers without realising what you're doing.
If you take an amp, connect it to a coil that has no speaker cone
attached to it, and try to drive it increasingly hard, there will come
a point at which you're completely saturating the output transistors.
The amplifier absolutely _cannot_ produce a voltage swing at its
output any greater than it would get by connecting the output rail to
one or other of its power supply rails (which is essentially what
happens when the output drivers are full on). If this happens before
you hit the top of the input signal, the output will have a flat top -
everything above a certain limit will be clipped down to that level.
Taken to an extreme, the output waveform will start to look more and
more like a square wave. As that happens, you get more and more
high-frequency harmonics that weren't in the original signal. The
crossover will divert that power to the tweeters, which is what
damages them.
p.
--
^D
Ian Molton
Glenn Richards <squi...@argonet.co.uk> wrote:
> But the original point is correct, it's easier to blow a 100W pair of
> speakers with a 50W amp than a 200W amp, as the 50W amp would overload
> and go into distortion, frying your tweeters!
Hahahaha. bollocks.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Lead me not into temptation, I can find it myself...
White Trash
Matthew Burke <m.b...@argonet.co.uk> Was overjoyed with
> 4. Enjoy the great sound of /2000W PMPO/ music power
>
>aaaahhhhhh! BOOM! BOOM! BOOM!
So that's roughly 125W/250W then. [PMPO is a huge exaggeration]
In a statement from ha...@zetnet.co.uk (Ian Molton)
>Well, that is *bollocks* The amp clips when the *input* level is too >high not the *output* level.
(snippety snip!)
Well yes & no (I think). Feeding a huge signal into a pre-amp will
distort, it's being given more than it could cope with. But increasing
the volume above and beyond the point of saturation will clip as has
been said, you can't expect an amp to supply more power than it recieves
from it's own supply.
Personally I enjoy listening to Acorn AM (Deutschland) through my A5000,
well when it's in one piece.
Al @ U.O.D. out
[More on the amp stuff after professional advice, now where's that
shrink?]
------------------------------------------------------------------------
"You've really worked out your banter, haven't you?"
"No this is different. It's spontaneous. It's called wit."
------------------------------------------------------------------------
Glenn Richards
In article <n7B4...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
> > But the original point is correct, it's easier to blow a 100W pair of
> > speakers with a 50W amp than a 200W amp, as the 50W amp would overload
> > and go into distortion, frying your tweeters!
>
> Hahahaha. bollocks.
Yeah, you'd probably fry those too! (Not literally of course!)
But if there's one thing speakers hate, it's distortion...
Glenn Richards
In article <19970415....@mightoak.demon.co.uk>,
b...@mightoak.demon.co.uk (Bob Latham) wrote:
> For a given volume with a given speaker. The HF unit is far more at risk
> from a small amp than a large one. If you don't get clipping at all,
> then either you listen very quiet, you have a monster power amp or very
> efficient speakers.
I think I fall into the second and third catagories, depending on which
system I'm talking about...
Upstairs: Small room, 2x80W RMS amp, 2x75W 88dB/W speakers, passive
sub-woofer.
Downstairs: Large room, Dolby Pro-Logic system, main amp 2x45W high current,
speakers 200W, centre amp 50W, speaker 150W, rear amp 2x15W, speakers 70W,
all speakers 96dB/W, active sub-woofer.
Nobody mention esoteric speaker cables! <g>
Ian Molton
Glenn Richards <squi...@argonet.co.uk> wrote:
> No, an amp will clip when the input /or/ output level is too high,
> although it happens in different ways. When the output clips (assuming
> we're talking about an audio amplifier) it's usually because the
> speakers hit their end-stops, creating an inductive short across the
> output, effectively sending a large DC current back into the system. The
> effect of this is a load "crack" sound through the speakers...it doesn't
> do them any good - I speak from experience!
Which was exactly my point - if the amp is too powerful, the speakers will clip (not the amp, as you say). This knackers them. And doesnt exactly do the
amp any good...
If the amp is less powerful than the speakers rating (allowing for
transients too) then you will not clip the speakers. thus the speakers are
safe.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Ian Molton
Ian Bannister <banni...@argonet.co.uk> wrote:
> No amplifier that clips on its input stages before the output does is
> worth calling a hifi amp.
Haha. yeah. right.
> How can an input running at a few 100s of
> millivolts run out of supply? The amp clips when there is not enough
> volts to drive the speakers any further.
Of course.
> This is taken into account by
> the design so a 60W amp would need around 65V to drive into 8ohms. The
> input stages would use typically +/-15V (30V) so would be in no danger
> of clipping.
The input stage does not necessarily work at that voltage.
> If you are running with low volume settings but still
> getting high output then this is a sign of an overloaded input.
Of course.
> But if its a decent amp and you're not running something like a CD into
> the disc (phono) input then any normal input levels should be OK.
Yes. Of course.
But The amp *shouldn't be* more powerful than the speakers are capable of
handling.
Ian Molton
Ian Bannister <banni...@argonet.co.uk> wrote:
>> Well, that is *bollocks*
> No it isn't, but what follows is a fine example..
Okay. let me re-write what I said, 'cos I introduced a couple of mistakes
myself.
Signal input too high - preamp can clip. This depends on design, though.
If preamp doesn't clip with too high input, amp will.
If o/p level is too high, speakers will clip. This is what damages them.
Therefore, using an amp below the rated power of the speakers is better.
That is what I was trying to say.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Ian Molton
Ian Bannister <banni...@argonet.co.uk> wrote:
>>> but only if you set the volume too high. Where as if you try to run a
>>> higher powered amp at the same wolume, then the amp will clip,
>>> damaging
> ^^^^^^ - Don't you mean lower?
No - I meant the speakers will clip, but wrote amp instead.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Try looking for a dry joint.
Be careful with that phrase... someone might pour some water in the
machine!
Philip Blundell
In article <19970418....@mightoak.demon.co.uk>,
Bob Latham <b...@mightoak.demon.co.uk> wrote:
>In message <n7C7...@zetnet.co.uk> Ian Molton wrote:
>> Glenn Richards <squi...@argonet.co.uk> wrote:
> [ wrong things ]
>
>No no no. For the last time. Clipping is an amplifier only phenomenon.
>For correct reading on the subject of clipping read posts by:
>
>Philip Blundell
>Patrick Herborn
>
>or any good book on amplifiers.
Thanks for the support, Bob. :-)
Might I suggest that people who are still not convinced wander on over
to rec.audio.tech or one of the other audio newsgroups? I'm sure
there are plenty of people there who will be able to settle the issue,
and c.s.a.hardware readers may be getting a little bored of this thread
by now.
p.
--
^D
William Gallafent
In article <n7D0...@zetnet.co.uk>, Ian Molton
<URL:mailto:ha...@zetnet.co.uk> wrote:
>
>
> Ian Bannister <banni...@argonet.co.uk> wrote:
>
> > No amplifier that clips on its input stages before the output does is
> > worth calling a hifi amp.
>
> Haha. yeah. right.
>
> > How can an input running at a few 100s of
> > millivolts run out of supply? The amp clips when there is not enough
> > volts to drive the speakers any further.
>
> Of course.
>
> > This is taken into account by
> > the design so a 60W amp would need around 65V to drive into 8ohms. The
> > input stages would use typically +/-15V (30V) so would be in no danger
> > of clipping.
>
> The input stage does not necessarily work at that voltage.
>
> > If you are running with low volume settings but still
> > getting high output then this is a sign of an overloaded input.
>
> Of course.
>
> > But if its a decent amp and you're not running something like a CD into
> > the disc (phono) input then any normal input levels should be OK.
>
> Yes. Of course.
>
> But The amp *shouldn't be* more powerful than the speakers are capable of
> handling.
>
On the contrary ... it should, in order to prevent clipping when playing back
material with a large dynamic range. I agree with Bob Latham, Philip Blundell
and Patrick Herborn. Perhaps we should have a 'qualification count' to see
who is more likely to be right about this one ... I'm quietly confident
myself.
Running a set of high quality monitor speakers rated at 75W from a pair of
250W monoblocks is unlikely to damage them before you damage your ears. Using
a 20W amp will wreck the tweeters very quickly if you turn it up.
> -Ian
>
--
Bill Gallafent
Ian Bannister
In article <n7D0...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
>
> Ian Bannister <banni...@argonet.co.uk> wrote:
>
> > If you are running with low volume settings but still
> > getting high output then this is a sign of an overloaded input.
>
> Of course.
>
> > But if its a decent amp and you're not running something like a CD into
> > the disc (phono) input then any normal input levels should be OK.
>
> Yes. Of course.
>
> But The amp *shouldn't be* more powerful than the speakers are capable of
> handling.
>
Perhaps the conclusion (if this thread ever ends) should be that to
overdrive *any* amp is a bad thing whatever speakers are connected. In other
words use an amplifier that you don't need to run near its maximum output.
Speakers IMHO should always have a rating at least the maximum amplifier
power. Then surely nothing can go wrong...?
--
Ian Bannister ___________________________
||---------------------/ \
|| < banni...@argonet.co.uk >
||---------------------\___________________________/
Sat,19 Apr 1997.16:25:11
Ian Molton
b...@mightoak.demon.co.uk (Bob Latham) wrote:
>>> But the original point is correct, it's easier to blow a 100W pair of
>>> speakers with a 50W amp than a 200W amp, as the 50W amp would overload
>>> and go into distortion, frying your tweeters!
> > <snip>
> Ian, on this subject you appear to be rude, crude and wrong.
Rude, maybe - I'm a bit stressed at the moment. sorry.
Wrong? The above statement is, but I didn't write it.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Anthony Clarke
In article <n7C7...@zetnet.co.uk>, Ian Molton
<URL:mailto:ha...@zetnet.co.uk> wrote:
>
> Glenn Richards <squi...@argonet.co.uk> wrote:
>
> > No, an amp will clip when the input /or/ output level is too high,
> > although it happens in different ways. When the output clips (assuming
> > we're talking about an audio amplifier) it's usually because the speakers
> > hit their end-stops, creating an inductive short across the output,
> > effectively sending a large DC current back into the system. The effect
> > of this is a load "crack" sound through the speakers...it doesn't do them
> > any good - I speak from experience!
>
> Which was exactly my point - if the amp is too powerful, the speakers will
> clip (not t he amp, as you say). This knackers them. And doesnt exactly do
> the amp any good...
>
> If the amp is less powerful than the speakers rating (allowing for
> transients too) then you will not clip the speakers. thus the speakers are
> safe.
From the bloke who normally agrees wuth you WRT. FP & StrongArm etc. I'm
sorry to inform you that I disagree ENTIRELY in fact I categorically state
you are *WRONG* !!! I'll even go a step further and state that it is much
easier for a 20W amplifer to blow a THOUSAND TRILLION MILLION MEGA Watt
speaker... to put this into some perspective. INSUFFICENT *CLEAN* POWER
1. Amplifers *DO* clip.... it is visible on an oscilloscope as a
flatening out of the audio wave at the crest and trough of a cycle.This
flatening is caused by the amp running out of dynamic headroom (SUFFICENT
*CLEAN* POWER) regardless of the load ie Speaker ... typically 6 - 8 ohms
depending on box loading and impedance at resonanse.....OK from the
speakers's end it "see's" this flatening out as a burst of DC. sum the crest
and trough clipping and the speakers' voice coil sees this as continuous
DC... which then resembles something like fusewire between the terminals of a
battery... heats up and the blue smoke gets out :-)).
2. When the amplifer clips it doesn't necessarily "bottom out" the
speaker.... this is a *mechanical* limitation of a speaker which is being
overdriven by an amplifer which PROBABLY does deliver more than sufficent
clean power to the speaker ie unclipped, but with such energy as to cause the
surround and spider to reach their mechanical limit thus causing the speaker
cone and attached voice coil (and voice coil former) to spring back with such
force that it slams into the magnet assembly. Resulting in an almighty
thwacking sound and physically damaging the voice coil former in-turn the
former rubs against the magnet assembly, scraping / scratchy sound as opposed
to a clipped sound ... ie. distorted... the now severly mis-shapened voice
coil assembly, will eventually cause the voice coil itself to be physically
worn; scraping away the lacquer on the voice coil as it continues to rub and
once again the blue smoke get out ..... phew..... hope this clears things up
without being too confusing.
Now for the blue smoke to clear !!!!..... :-))
I 've been following this thread since it first appeared and watched all
sorts of banter regards SPEAKER HUM. the person, whoever he was, that replied
that it was most likely an earth loop problem is 99.99% correct ... how this
developed into speakers power handling V's Amplifer clipping I believe to be
attributed to somebody rabbiting on about the hum you hear at discos' and PA
system...etc. .*PLEASE* whoever you were, DON'T give up your day job :-)))
TTFN.
PS. Sorry about the long winded reply but the poor person who originally
posted the speaker hum problem is probably still looking for the cure...
Attention to wiring and placement of all line level signal leads and greater
attention to earth loops is the answer.
< ANYTHING BUT WINTEL >
--
Anthony Clarke | Oak Seed Computers Pty. Ltd. | AMW Acoustic Labs |
mailto:ant...@om.com.au | Phone / Fax (066) 246 200 | Acorn Powered |
StrongArmed & Dangerous
LEGAL BIT ----> All Brand names and registered trade marks, acknowledged.
Disclaimer ---> All opinions expressed are those of the author, except
quoted comments by other parties.
Patrick Herborn
In article <n774...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> Ian Clark <roo...@cat1.demon.co.uk> wrote:
>
> > It's a good idea to have an amp more powerfull than your speakers,
> > because if your amp is less powerfull it will struggle to drive your
> > speakers, which can cause clipping of the signal, and wreck your
> > speakes. (So I'm told, but I am probably wrong.)
>
> very wrong
Actually totally correct. When an amp is driven into clipping, the spectral
energy density curve changes. As a result you get proportionately more HF
energy and less LF energy. This is bad for your HF units, and if prolonged
*WILL* destroy them. The amount of energy in the region of the spectrum
handled by the HF unit comprises about 6% of the total energy, so in a 100W
speaker system your HF unit will be rated at most at 10W. When you drive a
100W amp into clipping, it will be outputting more than 10W in the HF region,
and will consequently overload and destroy the HF unit.
If you were to use an amp that has a higher rating, then it is more difficult
to overload, and the HF energy will remain proportional to the total energy
(no clipping). So a 1kW amp driven at 500W will produce less HF energy than a
100W amp that is being overloaded, and hence will be less damaging to the HF
units. (all this assumes you are using the same input signal, of course)
> what do you think quiet bits in music do?
Sound quiet, of course.
> drive your amp at maximum power?
That depends on the class of the amplifier, of course. But what is important
is the PEAKS.... that's where the difference lies. A 100W amp overdriven can
quite easily drive 70W into your HF unit when overloaded. A 1kW amp can do,
but you'de be half deaf by the time that it managed it (1kW is awesomely
loud!!!).
> No comments about class A etc, please.
OK, I shall refrain. Now anyone care to comment on Class D amps? :-)
> -Ian
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. As far as we know, our computer has never had an undetected error.
Patrick Herborn
In article <DEm2GJAy...@cat1.demon.co.uk>
Ian Clark <roo...@cat1.demon.co.uk> wrote:
> Isn't class A always driven at full pelt. ;-)))
And Class D is always driven at zero.... IYKWIM....
> Erm, ditto.
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
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Patrick Herborn
In article <49973...@cloudnine.demon.co.uk>
Ian Wallace <i...@cloudnine.demon.co.uk> wrote:
> Are you sure??
No, he's wrong.
> As someone pointed out, when an amp clips, sound distorts (I think someone
> said that the wave turns square, which the speaker finds hard to cope with)
> which damages your speakers.
That is correct. A square wave has a high content of RF energy.
> Therefore, if you want to drive your 200W speakers at 200W, you buy a
> 300W amp and turn down the volume a bit, giving you headroom.
Ah, the man has sense. But you could buy a 200W amp with 16dB of dynamic
headroom and be safe... but that's getting rather involved.
> You may blow your speakers, but only if you set the volume too high.
Always the case. Unless you're using piezo electric speakers in which case
you'll blow the amp. You'll often see a halogen bulb in series to protect the
amp...
> Where as if you try to run a higher powered amp at the same wolume, then
> the amp will clip, damaging the speakers.
No, you mean a lower powered amp.
> > No comments about class A etc, please.
>
> *sigh* Technics...... ;-)
And what may I ask is wrong with Technics? :-) :-)
Cheers,
Pat.
--
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| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
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Patrick Herborn
In article <n7A6...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> No - clipping is caused when the input to your amp is driven too hard.
Of course. But whichever way you look at it, the amp can't produce the
required output and hence will clip....
> It is nothing to do with the speakers - not, that is, till you turn it up
> REALLY loud
Well, there is the rather pronounced effect of when the spider and suspension
reach the limit of their compliance. And also the possibility of cone
bottoming (if the spider/suspesion doesn't kick in first)
> I suspect they might be talking about impedance - which has nothing to do
> with power.
No no no... it means what it says. Always use a poweramp that which has a
higher rating than the speakers. You are aware, of course, that a 100W
speaker system will quite happily reproduce a 1kW peak, with only a minor
increase in distortion (assuming no bottoming) as long as the spectral energy
density curve doesn't change...
> > Isn't class A always driven at full pelt. ;-)))
>
> The amp, yes - the speakers? no.
Indeed... shoving DC through speakers is bad... well most of the time....
(think of Quad and you'll know what I mean)
> Ditto again <g>
:-)
> -Ian
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. I tried snorting coke...and almost DROWNED
Patrick Herborn
In article <na.2f29af477a....@argonet.co.uk>
Glenn Richards <squi...@argonet.co.uk> wrote:
> Although if you're overloading a 50Wpc amp then either you have very
> inefficient speakers or you need your hearing checked!
My speakers are quite efficient (about 103dB@1m when driven with 1W). But I
still like to wind it up to a few hunder watts per channel... the floor
starts moving and the paintings start rattling (allegedly... you can't hear
them at this stage).
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. Ghosts are merely unsubstantiated roomers.
Patrick Herborn
In article <n7B4...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> Glenn Richards <squi...@argonet.co.uk> wrote:
>
> > But the original point is correct, it's easier to blow a 100W pair of
> > speakers with a 50W amp than a 200W amp, as the 50W amp would overload
> > and go into distortion, frying your tweeters!
>
> Hahahaha. bollocks.
Oh dear... oh dear oh dear... Do not pass go, do not collect this month's AU,
instead proceed directly to your local library and get some books by the
likes of Messrs Thiele and Small and spend thy weekend reading... :-) :-)
> -Ian
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. I may not always be perfect, but I'm always me.
Patrick Herborn
In article <19970415....@mightoak.demon.co.uk>
b...@mightoak.demon.co.uk (Bob Latham) wrote:
> Ian, on this subject you appear to be rude, crude and wrong.
Seconded...
> Bob.
Cheers,
Pat.
--
·=============================================================================·
| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. GUT : God's Undiscovered Thoughts
Patrick Herborn
In article <n7AF...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> Well, that is *bollocks* The amp clips when the *input* level is too high
> not the *output* level.
Yes, and since the output is a function of the input, when the output gets
too high, it stands to reason that the input is too high FOR THE AMP, but it
does not stand to reason that the input itself is already subject to clipping
BEFORE it enters the amp.
> If your audio equipment is good, this will never happen.
There isn't an amp on the face of this planet that can't be overloaded. A
compromised used by nigthclubs is to pop a dynamic compressor on the input;
it's not perfect but it's a bit better....
> granted, clipping doesn't do a *huge* ammount of good,
It will fry your HF units, no iffs no buts, it WILL. Simple as that.
> but it's nowhere near as bad as frying your expensive speakers.
Then you've been fortunate, or not willing to wind your music up to 120dB
plus... I on the other hand enjoy music at this sort of level and have learnt
the lesson the hard and expensive way... clipping kills HF units.
> >> No comments about class A etc, please.
>
> > *sigh* Technics...... ;-)
>
> <evil grin> QUAD.
Krell.... :-)
> -Ian
Cheers,
Pat.
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| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. The surest way to be late is to have plenty of time.
Patrick Herborn
In article <3354C4...@eng.derby.ac.uk>
White Trash <clem...@eng.derby.ac.uk> wrote:
> Matthew Burke <m.b...@argonet.co.uk> Was overjoyed with
> > 4. Enjoy the great sound of /2000W PMPO/ music power
Then you ain't heard nothing yet...
> >aaaahhhhhh! BOOM! BOOM! BOOM!
Not without some serious speakers. You know it's loud when the your clothes
start moving and you feel your bones rattling....
> So that's roughly 125W/250W then. [PMPO is a huge exaggeration]
Yes, that sounds about right.
> Well yes & no (I think). Feeding a huge signal into a pre-amp will
> distort, it's being given more than it could cope with.
Indeed.
> But increasing the volume above and beyond the point of saturation will
> clip as has been said, you can't expect an amp to supply more power than it
> recieves from it's own supply.
Correct.
> Personally I enjoy listening to Acorn AM (Deutschland) through my A5000,
> well when it's in one piece.
:-)
Cheers,
Pat.
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Immensely inspiring tagline follows....
.. 66MHz ain't fast enough!
Patrick Herborn
In article <n7D0...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> But The amp *shouldn't be* more powerful than the speakers are capable of
> handling.
Oh dear. Let's clean up a few misconceptions before we proceed....
A speaker system rating is the maximum power that it will handle for extended
periods of time without sustaining any damage that could be classified above
and beyond that of "normal wear and tear". This tends to be pink noise, and
as a result is (unlike music) time invariant. The speaker rating tells you
ABSOLUTELY NOTHING about a speaker system's dynamic properties (an MLSSA
graph will, though).
It is not uncommon for a speaker system to be able to sustain an overload of
10 to 100 times it's rating provided that a) it doesn't as very long and b)
it has a spectral energy distribution that is similar to pink noise (which
itself is similar to music). If either of these two conditions are not met,
then damage can result from overdriving the speaker system.
An amplifier's rating is the maximum power that it can deliver continuously
into a resistive load equal to that of a speaker's resistive load.
Measurements are taken using a steady state sine wave (unmodulated) at 1kHz.
It does not tell you anything about an amplifier's dynamic response. The
distortion figures quoted are completely meaningless because those are
distortion figures for a purely resistive load; a speaker system is reactive
and highly dynamic. What it boils down to is that the tests are totally
inappropriate.
It is highly unusual to find an amplifier that is able to deliver 100 or even
10 times it's rated power output into a load; in short if you have a 100W amp
and a 100W speaker system, the amp will NOT be able to drive the speaker to
it's full potential. Any attempt to do so will result in the amp overloading.
This in turn changes the spectral energy density curve and by condition (b)
above, that will result in damage to the speakers.
A better approach is to go for a more powerful amplifier. While it is true
that the more powerful amplifier will be capable of delivering a steady state
signal more powerful than the steady state rating of the speaker system, the
very nature of the music prevents this from happening.
The difference between the average level of the music and the peak is about
16dB for pop music, slightly less for rock, and a whole lot more for
classical. So sticking with a figure of 16dB for now, that means that the
average level is 1/40 of the peak. If a 100W amp can deliver 200W for short
periods of time, then your the average would be 5 watts (1/40*200)... not
very much is it? And certainly a whole lot less than the speaker rating!! So
the speaker isn't being used anywhere near it's potential, and any attempt to
do so will destroy it.
If you were to go for a more powerful amplifier, and to keep things simple
we'll assume that it too is capable of delivering twice it's rated power for
short periods of time, then it will become clear that it is possible to
utilise more of the speaker's potential. Say you go for a 400W amp, which
would make it's maxiumum output before clipping 800W, then this would equate
to 20W average; still not very good is it? But better, and it will allow you
to 'wind it up' a bit more before clipping starts. Note that you're still
nowhere near the speaker's rating!!!
This is what sets a good amp apart from a bad one. A good one will be able to
deliver huge amounts of power for short periods of time... Another point to
watch out for is how stable an amplifier is into a dynamic load;
manufacturers don't tell you about these things, partly because it's
difficult to measure, partly because they'de lose a lot of sales.
If you do find an amplifier with 16dB dynamic headroom, you're a) very
fortunate, b) very rich, c) probably designed it yourself and d) quite
possibly not from this planet. So until amplifiers like this become
commonplace, you're just gonna have to get an amp whose rating is greater
than that of your speakers.
But, in the end there is NO substitute for going in, sitting down comfortably
and listening to a system; it's the definitive test. It will show you that
50W amps can sound better than 100W amps, and that the huge price tags on
some of the equipment is almost justifiable...
> -Ian
Cheers,
Pat.
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| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. I'm spending a year dead for Tax Purposes
Patrick Herborn
In article <n7D0...@zetnet.co.uk>
ha...@zetnet.co.uk (Ian Molton) wrote:
> If o/p level is too high, speakers will clip.
No, they won't. Unless you drive them like a maniac (read: like me)
> This is what damages them.
While it is true that mechanical damage can result, it is nowhere near as
drastic as literally burning the HF unit....
> Therefore, using an amp below the rated power of the speakers is better.
No, that's bad.
> That is what I was trying to say.
Go away and study speaker design, then you will learn why speakers are very
relilient to temporary 'overload' but will fry if driven with the wrong
spectral energy distribution. Then you will realise why using a more powerful
amp is better.
> -Ian
Cheers,
Pat.
--
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| Patrick Herborn, | p...@nanobyte.demon.co.uk | Primary Mail Address |
| Electronic Engineer. | pher...@libris.co.uk | Alternative Address |
'============================================================================='
Immensely inspiring tagline follows....
.. Earthquakes are Earth's way of saying, WAKE UP !!!!!!!!!!
Ian Molton
b...@mightoak.demon.co.uk (Bob Latham) wrote:
> I have to say Ian I disagree. Maybe it's because we are saying the same
> thing in different ways but I cannot endorse you statements above..
> An amplifier clips when it can no longer swing the output voltage
> required by the signal because the output devices saturate against the
> supply rails. This can be overcome by either reducing the gain of the
> power amp, reducing the input signal (as you said) or using a power amp
> that can swing a greater output voltage - a bigger amp. Only the latter
> is an improvement, the other two are just turning down the volume.
That is correct - And what I was trying to say.
> Kef Electronics published a paper some time back showing voice coil
> temperatures and what happens to them at clipping - they fly up and the
> usual result is the laquer holding the coil boils creating bubbles on
> the surface. When this cools, the voice coil now rubs on the magnet and
> only needs a bin to complete it's life cycle.
And overloading the tweeters by using a too powerful amp won't heat them up
just a *teensy* bit? besides, if you are using a transformer to match the
impedance etc., then when you have a long period with the same output level,
the tweeter will have almost no Pd across it.
ie. same output level meaning no change in o/p voltage.
-Ian
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Why does the man in the mask drink Metz? ... Because only beautiful people
drink Martini!
Ian Molton
pj...@thor.cam.ac.uk (Philip Blundell) wrote:
>> No, an amp will clip when the input /or/ output level is too high,
>> although it happens in different ways. When the output clips (assuming
>> we're talking about an audio amplifier) it's usually because the
>> speakers hit their end-stops, creating an inductive short across the
>> output, effectively sending a large DC current back into the system.
>> The effect of this is a load "crack" sound through the speakers...it
>> doesn't do them any good - I speak from experience!
> No, no. That's not the amplifier clipping - the speaker coils bottoming
> out against the end-stops is a different problem, though you're quite
> right that it's not good news either. However, it _is_ very immediately
> audible, and so you get plenty of warning that something is wrong.
> Clipping is a bit more insidious, because it's possible to damage your
> speakers without realising what you're doing.
yay! someone is agreeing with me!
-Ian
--
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He who laughs last thinks slowest.
Ian Molton
pj...@thor.cam.ac.uk (Philip Blundell) wrote:
> He only usually noticed that anything was wrong when the amp got so hot
> that it shut down, or the protection fuses blew, by which time his
> speakers were invariably wrecked.
How sad....
I wish I could afford the sort of cash he's been laying out.
-Ian
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Ian Molton
White Trash <clem...@eng.derby.ac.uk> wrote:
> Well yes & no (I think). Feeding a huge signal into a pre-amp will
> distort, it's being given more than it could cope with. But increasing
> the volume above and beyond the point of saturation will clip as has
> been said, you can't expect an amp to supply more power than it recieves
> from it's own supply.
This is what I have been trying to say....
> Personally I enjoy listening to Acorn AM (Deutschland) through my A5000,
> well when it's in one piece.
Is that like realaudio or something?
-Ian
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Malcolm Knight
In article <n7DB...@zetnet.co.uk>, Ian Molton
<URL:mailto:ha...@zetnet.co.uk> wrote:
>
> b...@mightoak.demon.co.uk (Bob Latham) wrote:
> > Kef Electronics published a paper some time back showing voice coil
> > temperatures and what happens to them at clipping - they fly up and the
> > usual result is the laquer holding the coil boils creating bubbles on
> > the surface. When this cools, the voice coil now rubs on the magnet and
> > only needs a bin to complete it's life cycle.
>
> And overloading the tweeters by using a too powerful amp won't heat them up
> just a *teensy* bit? besides, if you are using a transformer to match the
> impedance etc., then when you have a long period with the same output level,
> the tweeter will have almost no Pd across it.
All this talk of frying tweeters makes me very glad that I have active
speakers by 'B' (of B&W) with the crossover at the input to the amp. 200
watts of bass amplifier and 100 watts of HF per channel driving the cones
without a cross over in the way gives very tight control and the integrated
design won't let the amplifier fry the tweeter. A temperature sensor on the
coil shuts down the amplifier. A bit disconcerting when pumping out high
level low dynamic stuff - but cheaper than new kit.
If I run that old Hi-Fi News test CD of the slamming garage door at high
volume it frightens the life out of anyone within earshot. :-)
And (just so I can get back on topic) if I run the same CD on the Acorn I
have to spend another fourpence on a new speaker.... :-)
--
Malcolm Knight
Brett Laniosh
In article <n7C7...@zetnet.co.uk>, Ian Molton
<URL:mailto:ha...@zetnet.co.uk> wrote:
>
> If the amp is less powerful than the speakers rating (allowing for
> transients too) then you will not clip the speakers. thus the speakers are
> safe.
Totally incorrect.
--
Brett Laniosh Redditch & Bromsgrove CAMRA Acorn User
<mailto:br...@g4nzk.demon.co.uk> <http://www.g4nzk.demon.co.uk/>
An oblique strategy -
Remove specifics and convert to ambiguities
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
> Actually totally correct. When an amp is driven into clipping, the
> spectral energy density curve changes. As a result you get
> proportionately more HF energy and less LF energy. This is bad for your
> HF units, and if prolonged *WILL* destroy them. The amount of energy in
> the region of the spectrum handled by the HF unit comprises about 6% of
> the total energy, so in a 100W speaker system your HF unit will be rated
> at most at 10W. When you drive a 100W amp into clipping, it will be
> outputting more than 10W in the HF region, and will consequently
> overload and destroy the HF unit.
therefore, that amp is too powerful. a smaller amp wouldn't put as many watts
in the HF region.
-Ian
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Consciousness: that annoying time between naps.
Glenn Richards
In article <n7D0...@zetnet.co.uk>, ha...@zetnet.co.uk (Ian Molton) wrote:
> But The amp *shouldn't be* more powerful than the speakers are capable of
> handling.
Ideally it should be the same power rating as the speakers, however the
chances of that are very small. Best to buy the amp with the next rating
above your speakers rather than below...although speakers hitting their end
stops is not good, it's less harmful than the amp distorting, which will fry
your tweeters.
Ask anyone at What Hi-Fi magazine, or any hi-fi shop!
Glenn
--
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Squirrel Solutions [ rich...@2squirrels.arcticbb.demon.co.uk]
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Anti-Spam: Remove 3 - 1 squirrels to reply
Nicholas Kitchener
Glenn Richards <squi...@argonet.co.uk> wrote:
>Downstairs: Large room, Dolby Pro-Logic system, main amp 2x45W high current,
>speakers 200W, centre amp 50W, speaker 150W, rear amp 2x15W, speakers 70W,
>all speakers 96dB/W, active sub-woofer.
>
Hmm here you go (not that you'll be interested):
Harmon Karrdon AVI200:
65W RMS front three channels, 25W RMS double surround channels.
40 Amps max.. according to the blurb (about 250W RMS in total).
Front Speakers
Mission 734s -6dB@38Hz Max 125W/C wired by: Biwired with QuDos
Cannon SC20 (?) Max 100W wired by: Bainbridge
Surround
Technics (them balls..) 25W.
Sources:
Pioneer Laserdisc player (acts as CD player too) Gamma drive.
Puresonic interconnect.
Technics Radio bit.
Bainbridge interconnect
Panasonic Video..
Original Technics/Panasonic interconnect :(
Wot no active? Well no- the speakers I've got can make me feel sick to
start with and I live in a first floor flat.. :(
>Nobody mention esoteric speaker cables! <g>
Ah, what about esoteric interconnects then.. ;)
Nick.
+-
Nicholas Kitchener, Software Engineer, Logica UK
_kitchenern@logica.com____http://www.logica.com_
Please remove ANTISPAM on replying via email,
any junk mail will be bounced to your postmaster.
Andy Edgeworth
In message <5ja7a9$t...@lyra.csx.cam.ac.uk> Philip Blundell wrote:
> >
> >No no no. For the last time. Clipping is an amplifier only phenomenon.
> >For correct reading on the subject of clipping read posts by:
> >
In my experience, clipping happens whenever signal limitation takes place, whether
this is electronic (pre-amp, main amp etc) or mechanical (overdriven loudspeaker)
To say that it is just caused by this or that is just a tad blinkered ;-)
There is also the phenomenon of 'soft' clipping that can happen when a well designed
amplifier attempts to limit the distortion caused by overdriving, by softening the
waveform tops, which mostly just causes harmonic distortion, a much more acceptable
effect.
All IMHO of course. I wouldn't dare take on the combined forces of the audiophiles!!!
who would argue all day and every day about this and most other things audio.....
--
Andy Edgeworth
Kieran L. Brown
[snip huge thread about clipping]
Wouldn't it be safe to summarise this whole thread thus:
1) Never overdrive your speakers (as it hurts them)
2) Never overdrive your amplifier (as it will hurt *something*)
as either of these things is likely to cause much damage.
Can we stop this off-topic thread now?
... ARM Powered - I+t+l Outside.
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White Trash
Ian Molton wrote:
>
<snippy snip snip>
> This is what I have been trying to say....
It seems most people have been saying the same thing in different
ways, possibly being put off by the technical jargon and figures bieing
banded about replying to those who were totally out (I had some problems
following a few of the explanations & I'm studying thew damnd things.
Though this probably says more about me *uncomfortable, embarrassed
shuffle, stares meaningfully at shoes*).
>> Personally I enjoy listening to Acorn AM (Deutschland) through my >>A5000, well, when it's in one piece.
> Is that like realaudio or something?
> -Ian
Sadly no. This phenomenon was covered in AU about four years or so ago.
It transpires that something in the audio(?) circuitry is nearly
configured for reception of German radio (best heard through a hi-fi
with headphones at full belt), as I recall I think the A3000 did
something similar.
BTW, does anyone know which VR/pot i should twiddle to regain colour on
my Electron, i've just resurrected it after giving it a few years off &
would like to know which biorhythm i'm looking at. (new thread)
------------------------------------------------------------------------
"You've really worked out your banter, haven't you?"
"No this is different. It's spontaneous. It's called wit."
------------------------------------------------------------------------
PS. after reading some of the audio specs that have crossed this thread
i've become really envoius. It's just NOT fair. <end of tantrum>
Philip Blundell
In article <n7DF...@zetnet.co.uk>, Ian Molton <ha...@zetnet.co.uk> wrote:
>Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>> at most at 10W. When you drive a 100W amp into clipping, it will be
>> outputting more than 10W in the HF region, and will consequently
>> overload and destroy the HF unit.
>
>therefore, that amp is too powerful. a smaller amp wouldn't put as many watts
>in the HF region.
Enough! Enough! Ian, please go to the rec.audio newsgroups if you
want to carry on with this.
For the record, no, a smaller amp won't put out as many watts in the
HF region if it clips equally much. But (a) it doesn't take much
power to destroy a tweeter, and (b) a smaller amp will tend to clip
_more_ because the nutcase at the controls will turn the wick up to
get the same volume.
p.
--
^D
Chris Walker
In article <5jfqri$3...@romeo.logica.co.uk>, Nicholas Kitchener
<URL:mailto:kitch...@logica.ANTISPAM.com> wrote:
[snip]
>
> Ah, what about esoteric interconnects then.. ;)
What about the relevance to c.s.a.hardware? Although I did enjoy
reading the replies from Patrick Herborn. How he manages to remain so
patient with people I'll never know.
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Iain Anderson
Nicholas Kitchener (kitch...@logica.ANTISPAM.com) wrote:
> Glenn Richards <squi...@argonet.co.uk> wrote:
> Ah, what about esoteric interconnects then.. ;)
10Base5, and the widest-bodied plugs you can find. You'll want a junior
hacksaw to cut the cable to length. If it can carry 10Mbit data over 100
meters, it's more than adequate for audio over 20cm. And it looks totally
the business.
====
Iain
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>>> But the original point is correct, it's easier to blow a 100W pair of
>>> speakers with a 50W amp than a 200W amp, as the 50W amp would overload
>>> and go into distortion, frying your tweeters!
>> Hahahaha. ********
> Oh dear... oh dear oh dear... Do not pass go, do not collect this
> month's AU, instead proceed directly to your local library and get some
> books by the likes of Messrs Thiele and Small and spend thy weekend
> reading... :-) :-)
no - it will only go into distortion if you try to get the same output out
of it as the 200 watt amp.
-Ian
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Nicholas Kitchener
<Gears and cogs creaking>
SELECT * FROM BSC_SOFTWARE_ENGINEERING WHERE COURSE_NAME LIKE '%NETWORK%';
Hmm.. FFT... Harmonics.... BPS.. Networks. ..
</Gears and cogs creaking>
Surely the 10B5 cable is going to be tuned to a specific set of harmonics
(would this be a wider range than normal audio?) to carry the signals at
high rate of BPS. Anyone like to do some testing?
I wonder what net optic fiber sounds like used to connect a optic DAC?
Nick.
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any junk mail will be bounced to your postmaster.
Defense:
Q: Doctor, did you say he was shot in the woods?
A: No, I said he was shot in the lumbar region.
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>> If your audio equipment is good, this will never happen.
> There isn't an amp on the face of this planet that can't be overloaded.
> A compromised used by nigthclubs is to pop a dynamic compressor on the
> input; it's not perfect but it's a bit better....
I meant that if you have equipment which doesn't give > line level output
you won't have a problem. of course you can overload any amp...
>> granted, clipping doesn't do a *huge* ammount of good,
> It will fry your HF units, no iffs no buts, it WILL. Simple as that.
Again - if your amp, within normal operating parameters, can fry your
speakers, either it is too powerful, or your speakers are not rated high
enough.
I consider clipping to be approx. equal to a full amplitude square wave.
This is within normal operating parameters. therefore, your speakers
should be able to cope. otherwise it's your problem if you knacker them.
> Then you've been fortunate, or not willing to wind your music up to
> 120dB plus...
I doubt my amp has ever been above 5watts - and that's deafening!
>>>> No comments about class A etc, please.
>>> *sigh* Technics...... ;-)
>> <evil grin> QUAD.
> Krell.... :-)
mmm. not come across krell - must see if it's any good sometime.
I like my quad very much... It is connected to a pair of radford monitors.
1bass, 2mid, and 2tweeters per cabinet.
-Ian
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Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Why is 'abbreviation' such a long word?
Ian Molton
Anthony Clarke <ant...@om.com.au> wrote:
> 1. Amplifers *DO* clip.... it is visible on an oscilloscope as a
> flatening out of the audio wave at the crest and trough of a cycle.This
> flatening is caused by the amp running out of dynamic headroom
> (SUFFICENT *CLEAN* POWER)
Of course.
> 2. When the amplifer clips it doesn't necessarily "bottom out" the
> speaker.... this is a *mechanical* limitation of a speaker which is
> being overdriven by an amplifer which PROBABLY does deliver more than
> sufficent clean power to the speaker ie unclipped, but with such energy
> as to cause the surround and spider to reach their mechanical limit thus
> causing the speaker cone and attached voice coil (and voice coil former)
> to spring back with such force that it slams into the magnet assembly.
> Resulting in an almighty thwacking sound and physically damaging the
> voice coil former in-turn the former rubs against the magnet assembly,
> scraping / scratchy sound as opposed to a clipped sound ... ie.
> distorted... the now severly mis-shapened voice coil assembly, will
> eventually cause the voice coil itself to be physically worn; scraping
> away the lacquer on the voice coil as it continues to rub and once again
> the blue smoke get out ..... phew..... hope this clears things up
> without being too confusing.
Agreed.
> OK from the speakers's end it "see's" this flatening out as a burst of
> DC. sum the crest and trough clipping and the speakers' voice coil sees
> this as continuous DC... which then resembles something like fusewire
> between the terminals of a battery... heats up and the blue smoke gets
> out :-)).
I suspect the blue smoke would be comming out of my impedance matching coils
rather than my tweeters....
and on that point, I would agree entirely.
> I'll even go a step further and state that it is much easier for a 20W
> amplifer to blow a THOUSAND TRILLION MILLION MEGA Watt speaker... to put
> this into some perspective. INSUFFICENT *CLEAN* POWER
And I would say that the amp is being used outside it's normal parameters.
the clipping occurs when the input (and as Pat says, therefore the output)
is driven hard enough for the amp not to be able to supply the output power
required.
BUT. A good 20W amp being driven by a <proper> output (say CD player),
connected to a 40W capable pair of speakers would be fine. even at full
power.
Now If I swapped the 20W amp for a 1000W amp, the speakers get wrecked at
full output power. not because of clipping in the amp, but because the
speakers cannot handle that power.
in both cases, the amps DONT clip - because the input is of the correct
level.
so, my original point, a well designed amp, connected to a pair of speakers
capable of handling transients twice that of it's output rating, should not
damage the speakers, even at full gain, so long as the input is within
the spec of the amp.
Oh, and sorry for using the word b******* before - as I said, I have been a
bit stressed recently.
It seems we have been talking at cross purposes, I believe.
-Ian
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Ian Molton
Ian Bannister <banni...@argonet.co.uk> wrote:
> Yes I agree. Perhaps the conclusion (if this thread ever ends) should be
> that to overdrive *any* amp is a bad thing whatever speakers are
> connected. In other words use an amplifier that you don't need to run
> near its maximum output. Speakers IMHO should always have a rating at
> least the maximum amplifier power. Then surely nothing can go wrong...?
That's what I've been trying to say! phew - thread over? I hope...
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Ian Molton
Brett Laniosh <br...@g4nzk.demon.co.uk> wrote:
>> If the amp is less powerful than the speakers rating (allowing for
>> transients too) then you will not clip the speakers. thus the speakers
>> are safe.
> Totally incorrect.
In what way? I never said you couldn't clip the amp, did I?
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
> But, in the end there is NO substitute for going in, sitting down
> comfortably and listening to a system; it's the definitive test. It will
> show you that 50W amps can sound better than 100W amps, and that the
> huge price tags on some of the equipment is almost justifiable...
Totally agree - but I don't see why, even if you buy a powerful amp to get
the dynamic range, that you need to drive a pair of speakers which are rated
far below the amps peak output. not all the signals going through my amp are
music. My CD player gives a DC level for about 1.5 seconds on strting. not
very healthy for speakers of a low rating, wouldn't you say? that's why I
chose a pair of speakers rated above my amps *maximum sustained* power
output.
Mmm. I paid nothing for the amp. I reconditioned an old Quad I was given.
sounds gorgeous.
Probably only driven at about 5watts output, and deafening even then!
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Ever stop to think, and forget to start again?
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
>> Ian, on this subject you appear to be rude, crude and wrong.
> Seconded...
look, I said sorry, okay?
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
According to my calculations the problem doesn't exist.
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
> Go away and study speaker design, then you will learn why speakers are
> very relilient to temporary 'overload' but will fry if driven with the
> wrong spectral energy distribution. Then you will realise why using a
> more powerful amp is better.
I am fully aware of that. and I know speaker design is a black art.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
The Gene Pool could use a little Chlorine...
Ian Molton
Patrick Herborn <p...@nanobyte.demon.co.uk> wrote:
> Indeed... shoving DC through speakers is bad... well most of the
> time.... (think of Quad and you'll know what I mean)
*dreams* of a pair of quad electrostatics.
or ten.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Try looking for a dry joint.
Be careful with that phrase... someone might pour some water in the
machine!
Nicholas Kitchener
>>>> No comments about class A etc, please.
>>> *sigh* Technics...... ;-)
>> <evil grin> QUAD.
> Krell.... :-)
Audio Note Ongaku ....
David Higton
In message <n7C7...@zetnet.co.uk>, Ian Molton
>> although it happens in different ways. When the output clips (assuming
>> we're talking about an audio amplifier) it's usually because the
>> speakers hit their end-stops, creating an inductive short across the
>> output, effectively sending a large DC current back into the system. The
>> effect of this is a load "crack" sound through the speakers...it doesn't
>> do them any good - I speak from experience!
>clip (not the amp, as you say). This knackers them. And doesnt exactly do the
>amp any good...
This really doesn't happen as you describe. It is only possible to make
speakers hit their end-stops if you drive them very hard at frequencies
well below the lowest frequency they're designed for. If you do that,
well, I guess you don't deserve any sympathy.
If you do manage to make them hit the end stop, they abruptly stop
generating any back EMF, so, to that extent, what you say is true. But
the impedance doesn't drop to zero, it drops to the DC resistance of the
LF drive unit; a typical value for an 8 ohm drive unit would be about
5.5 ohms when cold, or more after being driven hard. Any reasonable
amplifier will cope with this, for a short time at least.
Try plotting the impedance versus frequency of a loudspeaker. You'll
find that it covers a wide range, from about 70% of the nominal value
at low and mid frequencies, to many times the nominal value at resonance.
Any amplifier has to routinely cope with this; it's not as difficult as
some people like to make out.
You can't make a mid or HF drive unit hit the end stops at any frequency
unless you don't have a crossover. They just don't, and can't, move
that far within their rated frequency ranges. HF units, for instance,
move less than a wavelength of visible light towards the upper end of
their frequency ranges, even at full power. This is a well-known problem
when trying to watch how the cone moves. As an indication, look at the
cones of your favourite speakers when being driven hard. The LF drive
unit is the only one you can see moving.
>If the amp is less powerful than the speakers rating (allowing for
>transients too) then you will not clip the speakers. thus the speakers are
>safe.
Dave
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Glenn Richards
> Hmm here you go (not that you'll be interested):
> Harmon Karrdon AVI200:
> 65W RMS front three channels, 25W RMS double surround channels.
> 40 Amps max.. according to the blurb (about 250W RMS in total).
> Front Speakers
> Mission 734s -6dB@38Hz Max 125W/C wired by: Biwired with QuDos
> Cannon SC20 (?) Max 100W wired by: Bainbridge
> Surround
> Technics (them balls..) 25W.
> Sources:
> Pioneer Laserdisc player (acts as CD player too) Gamma drive.
> Puresonic interconnect.
> Technics Radio bit.
> Bainbridge interconnect
> Panasonic Video..
> Original Technics/Panasonic interconnect :(
Oh, you want model numbers? Ok...
Main system:
Mission 760iSE loudspeakers, 75W power handling
Home-built passive sub-woofer
Tweaked pair of cheap Hinari speakers connected across + terminals of amp to
produce psuedo-surround effect (switchable).
Technics SU-VX600 amp, 2x80W RMS
Technics SL-PG320A CD player
Technics RS-BX606 3-head cassette deck
Aiwa AD-S950 3-head cassette deck with Dolby S
Denon TU-380RD RDS tuner
Video equipment:
Ferguson 3V43 4-head twin-speed hi-fi stereo VHS VCR (semi-pro model)
Ferguson 3V48 hi-fi VCR
(Both Ferguson machines have NICAM upgrade fitted by myself)
Granada (AKA Hitach) linear stereo 4-head VCR
Panasonic NV-366 4-head VCR
Philips 21" TV with RGB and CVBS inputs (sometimes used on A5000 too)
Matsui 14" colour TV
2 x Samsung 12" b/w TVs
Home cinema:
Technics SU-A700MkII amp, 2x45W RMS into 8 ohms
Kenwood SS-3300 Dolby Pro-Logic decoder with Time-Link, 50W centre amp,
2x15W rear channels, pre-outs.
10-band graphic EQ (usually bypassed, before anyone starts screaming!)
6 channel stereo mixing desk
DNR unit
Automatic video source switch (home built)
Multi-Link infra-red remote radio relay system
Home Cinema Loudspeakers:
Front : Gale Model 4 (200W, bi-wired)
Centre : Gale Centre 2 (drivers as Gale 4 only shielded)
Sub : Active version of home-built type on main system (100W)
Rear : JPW Mini Monitors (70W)
One last thing:
Technics SH-R500 universal programmable remote contol handset. :-)
Now the second system:
Celestion 1 loudspeakers
Akai AM-2650 amp (2x65W RMS)
Akai 5-band graphic EQ (only used when making recordings from the computer!)
Technics SL-PG200A CD player
Sony TC-FX25 cassette deck
Acorn A5000, unfiltered sound output! <g>
I've also got a couple of keyboards (the musical variety) that I hook up
occasionally. The main and second systems are in the same room, the second
system is placed so I can get decent sound from the computer. The systems
are also linked together through their tape loops...the home cinema is fed
off the main system, everything being connected to that.
> Wot no active? Well no- the speakers I've got can make me feel sick to
> start with and I live in a first floor flat.. :(
I can cause movements on the Richter scale with the home cinema setup - but
then that's what home cinema's all about isn't it!
Star Wars will never be the same again...I really gotta get myself a
laserdisc player!
> >Nobody mention esoteric speaker cables! <g>
> Ah, what about esoteric interconnects then.. ;)
I borrowed a mate's Monster Interlink 100 and replaced the free patch cord
between the CD and amp on the main system with it. I couldn't hear the
slightest difference...
Speaker cables on the other hand...a few years ago I replaced the
slightly-thicker-than-bell-wire stuff I had on my speakers (then Sony
SS-85E) with 13A mains cable... :-) An amazing difference!
I've got the Gales wired up with 45A cooker cable, but I think I might
replace it with 2 pairs of 90A meter tails!
Glenn Richards
In article <19970421....@nineteen.demon.co.uk>,
An...@nineteen.demon.co.uk (Andy Edgeworth) wrote:
> All IMHO of course. I wouldn't dare take on the combined forces of the
> audiophiles!!!
A sensible man... :-)
> who would argue all day and every day about this and most other things
> audio.....
Yes, it's an amazing effect when you put little pieces of tinfoil under your
CD player's mains cable. Of course, it has to be special "audiophile grade"
tinfoil, costing around £12 for a 1/2 metre length...
I am of course taking the p#*%. :-)
Philip Blundell
In article <na.72fccb477e....@argonet.co.uk>,
Glenn Richards <squi...@argonet.co.uk> wrote:
>Oh, you want model numbers? Ok...
>
>Main system:
>
>Mission 760iSE loudspeakers, 75W power handling
>Home-built passive sub-woofer
>Tweaked pair of cheap Hinari speakers connected across + terminals of amp to
>produce psuedo-surround effect (switchable).
>
>Technics SU-VX600 amp, 2x80W RMS
>Technics SL-PG320A CD player
>Technics RS-BX606 3-head cassette deck
>Aiwa AD-S950 3-head cassette deck with Dolby S
>Denon TU-380RD RDS tuner
Umm, fascinating though this is, could you move to some other
newsgroup please guys? I think c.s.a.hardware has suffered enough
from the "clipping" thread, without starting a "my hifi is better than
yours" thread.
phil (perfectly happy with his comparitively unimpressive Arcam Alpha 8 and
Mission 732s, thankyou very much).
--
^D
Ian Molton
ia...@prismtech.co.uk (Iain Anderson) wrote:
>>> Nobody mention esoteric speaker cables! <g>
>> Ah, what about esoteric interconnects then.. ;)
> 10Base5, and the widest-bodied plugs you can find. You'll want a junior
> hacksaw to cut the cable to length. If it can carry 10Mbit data over 100
> meters, it's more than adequate for audio over 20cm. And it looks
> totally the business.
or any decent shielded cable.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Pride is what we have. Vanity is what others have.
Ian Molton
b...@mightoak.demon.co.uk (Bob Latham) wrote:
> However untenable your position becomes Ian, you're not going to
> acquiesce are you?
no - seeing as Phillip Blundel (sp?) just effectively agreed with me by mail
> If you wish to believe this, carry on mate. We've done our best, it's
> your speakers/money.
My speakers have never been overdriven in their life.
-Ian
--
Hawk Software HTTP://www.users.zetnet.co.uk/hawk/
Lead me not into temptation, I can find it myself...