Safe for 4 ohms into 8 ohms?
zyx
it on a 12" speaker which is 8 ohms.
Jam away?
Eeyore
zyx wrote:
You won't do any harm.
Graham
Patrick Turner
That should be fine, jam away.
Its always OK to use a higher ohm value for speakers instead of a lower
value
on nearly all amps.
Patrick Turner.
Lord Valve
the know-it-alls on this NG, don't do it. Audiophools
rarely stress their gear, and consequently rarely
consider what may happen to it when it is operated
beyond design parameters - as guitar amplifiers
*routinely* are. You risk a condition known as high-
tension flyback if you run a tube guitar amp into a higher
than rated impedance; this will fry your power tube
socket, along with the tube in it. Lower-powered
amps are certainly not immune to this, judging by
the number of tube sockets I've replaced in Fender
Champs and small Gibsons over the years. Get
the correct impedance speaker.
Lord Valve
Expert
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FLY135
That's nearly all **solid state** amps. The Epi is a tube amp.
GregS
>Despite what you may have seen from a couple of
>the know-it-alls on this NG, don't do it. Audiophools
>rarely stress their gear, and consequently rarely
>consider what may happen to it when it is operated
>beyond design parameters - as guitar amplifiers
>*routinely* are. You risk a condition known as high-
>tension flyback if you run a tube guitar amp into a higher
>than rated impedance; this will fry your power tube
>socket, along with the tube in it. Lower-powered
>amps are certainly not immune to this, judging by
>the number of tube sockets I've replaced in Fender
>Champs and small Gibsons over the years. Get
>the correct impedance speaker.
>
>Lord Valve
>Expert
Consider the rated Z is just a nominal figure, and the real Z will rapidly
rise with frequency, every amp would be at risk according to your
advice. The rated Z is at a bass frequency. if you don't play
bass, then its not a relavant issue.
greg
Ian Iveson
>I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
>to try it on a 12" speaker which is 8 ohms.
>
> Jam away?
A bit risky. Anode voltage may rise higher than some parts can cope
with reliably.
As a general rule, SS amps don't care too much about a higher load
impedance, and valves are tolerant of a lower one.
cheers, Ian
Ian Iveson
> Consider the rated Z is just a nominal figure, and the real Z will
> rapidly
> rise with frequency, every amp would be at risk according to your
> advice. The rated Z is at a bass frequency. if you don't play
> bass, then its not a relavant issue.
Perhaps you might, step by step, check the logic of your argument.
Assuming similar characteristics, an 8 ohm speaker will rise to a
maximum impedance of twice that of the 4 ohm speaker. An amp designed
to be reliable at the maximum impedance of the 4 ohm speaker may not
be reliable at the maximum impedance of an 8 ohm speaker.
It would be OK if you stuck to bass.
cheers Ian
Eeyore
Lord Valve wrote:
> Despite what you may have seen from a couple of
> the know-it-alls on this NG, don't do it. Audiophools
> rarely stress their gear, and consequently rarely
> consider what may happen to it when it is operated
> beyond design parameters - as guitar amplifiers
> *routinely* are. You risk a condition known as high-
> tension flyback if you run a tube guitar amp into a higher
> than rated impedance; this will fry your power tube
> socket, along with the tube in it. Lower-powered
> amps are certainly not immune to this, judging by
> the number of tube sockets I've replaced in Fender
> Champs and small Gibsons over the years. Get
> the correct impedance speaker.
From just a 2:1 change in load impedance ?
You jest surely. Having an open on the output is another matter entirely of
course.
Graham
Eeyore
Ian Iveson wrote:
> zyx wrote
>
> >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> >to try it on a 12" speaker which is 8 ohms.
> >
> > Jam away?
>
> A bit risky. Anode voltage may rise higher than some parts can cope
> with reliably.
Oh puhleeze ! Is that nonsense or what ?
> As a general rule, SS amps don't care too much about a higher load
> impedance, and valves are tolerant of a lower one.
Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will
drive a 1 - 2 ohms load very well, yet many SS amps do it admirably.
Graham
Eeyore
Ian Iveson wrote:
Do tell me more about this reliability Ian !
Especially when a speaker's impedance can rise at some frequencies to easily TEN
TIMES the 'nominal' figure.
By your argument, driving the amplifier at such frequencies will destroy it.
> It would be OK if you stuck to bass.
It would be OK if you stuck to not making stuff up about which you know nought.
Graham
zyx
"zyx" <a...@def.ghi> wrote in message
news:45adf6eb$0$7643$4c36...@roadrunner.com...
>I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try
>it on a 12" speaker which is 8 ohms.
>
> Jam away?
>
Such mixed results.
who to believe... who to believe... :)
any links to learn more about it? By the way I already have an 12" 8 ohm
speaker so I asked.
Lord Valve
GregS wrote:
> In article <45AE2B96...@ix.netcom.com>, Lord Valve <detr...@ix.netcom.com> wrote:
> >Despite what you may have seen from a couple of
> >the know-it-alls on this NG, don't do it. Audiophools
> >rarely stress their gear, and consequently rarely
> >consider what may happen to it when it is operated
> >beyond design parameters - as guitar amplifiers
> >*routinely* are. You risk a condition known as high-
> >tension flyback if you run a tube guitar amp into a higher
> >than rated impedance; this will fry your power tube
> >socket, along with the tube in it. Lower-powered
> >amps are certainly not immune to this, judging by
> >the number of tube sockets I've replaced in Fender
> >Champs and small Gibsons over the years. Get
> >the correct impedance speaker.
> >
> >Lord Valve
> >Expert
>
> Consider the rated Z is just a nominal figure, and the real Z will rapidly
> rise with frequency, every amp would be at risk according to your
> advice. The rated Z is at a bass frequency. if you don't play
> bass, then its not a relavant issue.
Sorry, realworld experience puts the lie to your statement. No offense.
LV
Lord Valve
Eeyore wrote:
Sorry, realworld experience puts the lie to your statement.
Hope you are *profoundly* offended, you America-hating
fucktard.
Lord Valve
Expert
Hit by A Busch Lite
>
> who to believe... who to believe... :)
In the big picture of life, your likely do more damage to
your hearing than the speakers.
Without a matching load ( 4 == 4 , 8 == 8) the efficiency of the amp's
output won't be met and your end up with less power output
than what it is ideally capable of producing.
I'm be more leery of the wattage of the speaker than the mismatch of Z
but with a epi your ok.
>
> any links to learn more about it? By the way I already have an 12" 8 ohm
> speaker so I asked.
>
Trust me ! .. This *is* the internet you know !This topic is discussed
to death in most nwes groups.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
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Ian Iveson
> who to believe... who to believe... :)
You will have the same problem wherever you go, I'm afraid. Sometime
you will need to make a judgement. May as well be now.
It should be obvious that this "eeyor" either can't read or has no
grasp of simple logic, or both. Neither has he any real experience,
and seems not to know the meaning of the word "unreliable". Greg's
argument is clearly half-boiled.
My logic is unassailable, and what you propose is a bit risky. Whether
the risk is worth taking or not depends partly on the design of your
amp, the quality of its components, and the state it is in, and partly
on your propensity for taking risks.
Lord Valve is a professional with many years of relevant experience.
He seems to say the risk is not worth taking.
Personally, if the amp is in good, clean condition and is well made to
a sensible design, I wouldn't worry much about trying an 8 ohm
speaker. I would expect the sound to be compromised though because of
the shift in bandwidth and change in distortion content.
Consider: everyone agrees that an open circuit is not a safe load for
your amp. Everyone agrees that a 4 ohm speaker is a safe load.
Somewhere in between a 4 ohm speaker and infinity, your amp will
become seriously unreliable.
*No-one here knows where that point is*. The consequence of you
loosing the bet is potentially catastrophic. There is an outside
chance of carnage in microseconds.
The best speaker will be 4 ohms, without a doubt. Why mess about? Get
a 4 ohm speaker. Why take a risk in the meantime, even if you judge it
to be small?
> any links to learn more about it? By the way I already have an 12" 8
> ohm speaker so I asked.
Depends on what you already know, and how confident you are to apply
it to new situations. Ohm's law should suggest that, for the same
power output, a higher output impedance must lead to a higher voltage
across it. This higher voltage will be reflected to the primary side
of the transformer, leading to a higher maximum voltage at the valve
anodes and transformer primary winding.
An understanding of simple filters will explain why the bandwidth will
shift.
Some understanding of valve characteristics should explain why the
distortion content will change.
Nothing except experience will tell you whether this particular amp is
likely to be OK with an 8 ohm speaker, or whether it's sound will be
pleasing to you.
That's why Lord Valve is your best bet.
cheers, Ian
Phread
>
> "zyx" <a...@def.ghi> wrote in message news:45adf6eb$0$7643$4c36...@roadrunner.com...
>>I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" speaker which is 8 ohms.
>>
>> Jam away?
>>
>
> Such mixed results.
>
> who to believe... who to believe... :)
Dude!
Who to believe? Lord Valve is a musician who's been fixing guitar amps
for longer than you've been on the planet, most likely. Graham is a blow
hard know-it-all who responds to every question posted here even though
his actual knowledge of tube equipment is exactly zero.
I've been building and repairing tube equipment for 50 years, including guitar
amps, home stereo & PA amps, and ham radio transmitters and receivers.
Lord Valve is right. Doubling the load impedance on a tube guitar amp will
cause much larger voltage swings in the primary of the output transformer
(swings of thousands of volts!) which can cause arcs in the output tubes,
tube sockets and tranny.
Fred
Eeyore
Phread wrote:
> "zyx" <a...@def.ghi> wrote in message
> > "zyx" <a...@def.ghi> wrote in message
> >>I have an epi valve jr combo with 8" speaker that is 4 ohms. I want to try it on a 12" >>speaker which is 8 ohms.
>
> >>
> >> Jam away?
> >>
> >
> > Such mixed results.
> >
> > who to believe... who to believe... :)
>
> Dude!
>
> Who to believe? Lord Valve is a musician who's been fixing guitar amps
> for longer than you've been on the planet, most likely. Graham is a blow
> hard know-it-all who responds to every question posted here even though
> his actual knowledge of tube equipment is exactly zero.
Oh really ?
I'm a pro-audio designer with 35 yrs experience in the business and have plenty of knowledge of tube circuitry and I
even played a part in getting one tube guitar amp into volume production.
> I've been building and repairing tube equipment for 50 years, including guitar
> amps, home stereo & PA amps, and ham radio transmitters and receivers.
> Lord Valve is right. Doubling the load impedance on a tube guitar amp will
> cause much larger voltage swings in the primary of the output transformer
> (swings of thousands of volts!) which can cause arcs in the output tubes,
> tube sockets and tranny.
Utter garbage. The voltage swings on the primary of the output transformer are typically well *under* a thousand
volts. They cannot in any case exceed 2 x B+ in normal operation.
How many transformers have you designed btw ?
Graham
p.s.
to zyx, there are lots of amateurs here who reckon they know it all and dislike those with professional knowledge.
They regularly make fundamental errors of fact and interpretation.
There are only 2 professional designers here and they are Patrick Turmer and myself.
Lord Valve is a very experienced tube expert at the practical level but has no design experience AFAIK.
Eeyore
Ian Iveson wrote:
> zyx wrote
>
> > who to believe... who to believe... :)
>
> You will have the same problem wherever you go, I'm afraid. Sometime
> you will need to make a judgement. May as well be now.
>
> It should be obvious that this "eeyor" either can't read or has no
> grasp of simple logic, or both. Neither has he any real experience,
> and seems not to know the meaning of the word "unreliable". Greg's
> argument is clearly half-boiled.
>
> My logic is unassailable
No, you're an utter cretin who can barely make a single post without some
serious error.
Graham
Chris Hornbeck
know-it-all on this NG, don't worry.
Loudspeaker impedances are only the roughest kind
of estimate, good within a factor of ten, maybe.
Operation without load is dangerous because it can
cause (somewhat indirectly, but "cause") high
voltage arcing, often in the output transformer's
windings' insulation.
Operation with any load even remotely like a speaker
attached is safe. Never operate without a speaker
attached, but don't worry about some bogus number.
All good fortune,
Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau
tubegarden
Just get another 8 ohm speaker and wire them in parallel.
This NG would rather trade insults than help you solve your problem.
Yes, an 8 ohm resistor would work, sort of, but you can't hear the
resistor's heat output :)
Happy Ears!
Al
John Byrns
Eeyore <rabbitsfriend...@hotmail.com> wrote:
Oh really ?
Are you sure about that 2 x B+ stuff? Have you ever considered that the
transformer presents an inductive impedance to the tube(s) and if it is
not sufficiently damped the anode voltage can easily exceed 2 x B+ when
the tube is suddenly cut off?
> How many transformers have you designed btw ?
>
> to zyx, there are lots of amateurs here who reckon they know it all and
> dislike those with professional knowledge.
> They regularly make fundamental errors of fact and interpretation.
>
> There are only 2 professional designers here and they are Patrick Turmer and
> myself.
What evidence do you have that there are only two "professional
designers" here, there may be more than you suspect? Besides the fact
that someone is a "professional designer" doesn't guarantee that they
know what they are doing.
> Lord Valve is a very experienced tube expert at the practical level but has
> no design experience AFAIK.
Regards,
John Byrns
--
Surf my web pages at, http://fmamradios.com/
Chris Hornbeck
<rabbitsfriend...@hotmail.com> wrote:
>Especially when a speaker's impedance can rise at some frequencies to easily TEN
>TIMES the 'nominal' figure.
>
>By your argument, driving the amplifier at such frequencies will destroy it.
And furthermore a nominally stable (with nominal load) amplifier,
with nominal levels of voltage feedback, which includes conventional
guitar amplifiers, have very, very largely the same circuit voltages
irrespective of load, over a wide range.
The very real danger that has promulgated these myths is
with an unstable amplifier, for example a legacy pentode-
output guitar amplifier that oscillates when driven hard
unloaded; not unknown for lots of classic designs.
Oscillation, or even just overdrive, rapidly puts the
output valves into class C; dI/dT makes multi-kiloJolt
spikes across the output transformer when unloaded.
Any remotely reasonable load keeps dI/dT to as safe a
level as any other remotely reasonable load.
Much thanks, as always,
Phil Allison
"Eeysore the IDIOT "
> Utter garbage. The voltage swings on the primary of the output transformer
> are typically well *under* a thousand
> volts. They cannot in any case exceed 2 x B+ in normal operation.
** Really ?????
Says an utter fool who has obviously NEVER tested * that * naive theory.
Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes
on the output plates when operating into a speaker cab.
LVs phrase " high tension flyback " is a very apt one - cos it don't
happen with a resistive load.
> How many transformers have you designed btw ?
** More Red Herrings - anyone ??
....... Phil
Eeyore
John Byrns wrote:
> Eeyore <rabbitsfriend...@hotmail.com> wrote:
> > Phread wrote:
> >
> > > Doubling the load impedance on a tube guitar amp will
> > > cause much larger voltage swings in the primary of the output transformer
> > > (swings of thousands of volts!) which can cause arcs in the output tubes,
> > > tube sockets and tranny.
> >
> > Utter garbage. The voltage swings on the primary of the output transformer
> > are typically well *under* a thousand
> > volts. They cannot in any case exceed 2 x B+ in normal operation.
>
> Oh really ?
>
> Are you sure about that 2 x B+ stuff?
100%
> Have you ever considered that the
> transformer presents an inductive impedance to the tube(s) and if it is
> not sufficiently damped the anode voltage can easily exceed 2 x B+ when
> the tube is suddenly cut off?
The transformer will look like an inductor when there's no load.
When there's a load on the secondary you will see a load on the primary. That's
what transformers *DO* !
The load 'damps' the transformer's own inductance if you want to look at it like
that.
> > How many transformers have you designed btw ?
> >
> > to zyx, there are lots of amateurs here who reckon they know it all and
> > dislike those with professional knowledge.
> > They regularly make fundamental errors of fact and interpretation.
> >
> > There are only 2 professional designers here and they are Patrick Turmer and
> > myself.
>
> What evidence do you have that there are only two "professional
> designers" here,
Experience of the posters here.
> there may be more than you suspect?
Not to my knowledge.
> Besides the fact that someone is a "professional designer" doesn't guarantee
> that they know what they are doing.
Patrick and I do.
Graham
Eeyore
Phil Allison wrote:
> "Eeysore the IDIOT "
>
> > Utter garbage. The voltage swings on the primary of the output transformer
> > are typically well *under* a thousand
> > volts. They cannot in any case exceed 2 x B+ in normal operation.
>
> ** Really ?????
>
> Says an utter fool who has obviously NEVER tested * that * naive theory.
>
> Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes
> on the output plates when operating into a speaker cab.
In which case it's nothing to do with whether the load is a nominal 4 ohms or 8
ohms is it ?
Note that I did say 'in normal operation'. If you grossly abuse an amplifier,
all sorts of stuff can happen.
Graham
Phil Allison
" Eeysore the LYING POMMY CHARLATAN "
>> > Utter garbage. The voltage swings on the primary of the output
>> > transformer
>> > are typically well *under* a thousand
>> > volts. They cannot in any case exceed 2 x B+ in normal operation.
>>
>> ** Really ?????
>>
>> Says an utter fool who has obviously NEVER tested * that * naive
>> theory.
>>
>> Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV
>> spikes
>> on the output plates when operating into a speaker cab.
>>
>> LVs phrase " high tension flyback " is a very apt one - cos it
>> don't
>> happen with a resistive load.
>
> In which case it's nothing to do with whether the load is a nominal 4 ohms
> or 8
> ohms is it ?
** WRONG !
The higher Z value, if mismatched at the output, will induce larger spikes.
At some stage, insulation in the OT, the valves or sockets gives up, with a
BANG.
> Note that I did say 'in normal operation'.
** Normal operation ( for a guitar amp) is the case.
As I said - YOU have NEVER tested it.
Cos YOU are a posturing, pig ignorant, ASD fucked
POMMY CHARLATAN !!
....... Phil
Eeyore
Phil Allison wrote:
>
> As I said - YOU have NEVER tested it.
So how about you tell us how you got it to do this then ?
Graham
Phil Allison
"Eeysore the IDIOT "
> So how about you tell us how you got it to do this then ?
** Got what to do what - exactly ??
...... Phil
Eeyore
Phil Allison wrote:
Get the amplifier to create 5kV on the OPT primary !
Graham
Phil Allison
"Eeysore the FUCKING IDIOT "
>> > So how about you tell us how you got it to do this then ?
>>
>> ** Got what to do what - exactly ??
>
> Get the amplifier to create 5kV on the OPT primary !
** Already told you.
....... Phil
Eeyore
Phil Allison wrote:
You did NOT say how you did it.
Graham
Phil Allison
>> >> ** Got what to do what - exactly ??
>> >
>> > Get the amplifier to create 5kV on the OPT primary !
>>
>> ** Already told you.
>
> You did NOT say how you did it.
" Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV
spikes
on the output plates when operating into a speaker cab.
LVs phrase " high tension flyback " is a very apt one - cos it don't
happen with a resistive load. "
" Normal operation ( for a guitar amp) is the case. "
As I said - YOU have NEVER tested it.
Cos YOU are a posturing, pig ignorant, ASD fucked
Eeyore
Phil Allison wrote:
> "Eeysore the FUCKING IDIOT "
>
> >> >> ** Got what to do what - exactly ??
> >> >
> >> > Get the amplifier to create 5kV on the OPT primary !
> >>
> >> ** Already told you.
> >
> > You did NOT say how you did it.
>
> " Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV
> spikes on the output plates when operating into a speaker cab.
>
> LVs phrase " high tension flyback " is a very apt one - cos it don't
> happen with a resistive load. "
>
> " Normal operation ( for a guitar amp) is the case. "
Ok - so *how easily* ?
If you can't provide an answer you'll be seen to be simply posturing.
Graham
Phil Allison
"Eeysore the LYING CHARLATAN "
>> >> >> ** Got what to do what - exactly ??
>> >> >
>> >> > Get the amplifier to create 5kV on the OPT primary !
>> >>
>> >> ** Already told you.
>> >
>> > You did NOT say how you did it.
>>
>> " Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV
>> spikes on the output plates when operating into a speaker cab.
>>
>> LVs phrase " high tension flyback " is a very apt one - cos it
>> don't
>> happen with a resistive load. "
>>
>> " Normal operation ( for a guitar amp) is the case. "
>
> Ok - so *how easily* ?
** The question has been answered.
Do your own tests if you want proof.
Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes "
for confirmation the phenomenon is well known.
....... Phil
Eeyore
Phil Allison wrote:
So you're just making it up ( you can't or refuse to explain it ).
Just as I expected from a toaster repairman.
Graham
Phil Allison
"Eeysore the Raving LUNATIC" "
>> ** The question has been answered.
>>
>> Do your own tests if you want proof.
>>
>> Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes
>> "
>> for confirmation the phenomenon is well known.
>
>
> So you're just making it up ( you can't or refuse to explain it ).
** What an UTTER non sequitur !!!!!!!!
Someone one ought to shoot this pile of pommy shit right in the head.
Then ask the Queen for a medal for services to the British Empire.
....... Phil
Eeyore
Phil Allison wrote:
> "Eeysore the Raving LUNATIC" "
>
> >> ** The question has been answered.
> >>
> >> Do your own tests if you want proof.
> >>
> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback spikes
> >> "
> >> for confirmation the phenomenon is well known.
> >
> >
> > So you're just making it up ( you can't or refuse to explain it ).
>
> ** What an UTTER non sequitur !!!!!!!!
So go-on, what causes the 5kV ?
You don't know do you ?
Graham
Arny Krueger
message news:45AF5784...@hotmail.com
Ironically, if one takes Phil's advice and searches alt.guitar.amps for
posts about flyback spikes, you find him dodging the same basic question you
asked about generating 5 Kv spikes around 2/25/2003, for example.
Searching further, it looks like people are talking about loose 1/4 plugs,
and the like. Based on what I know about generating inductive spikes, a wide
range of inductances can suffice, and saying that 8 ohm speakers are always
safe with a given amp would be a real stretch.
Phil Allison
"Eeysore the Raving CRIMINAL LUNATIC" "
>> " Normal operation ( for a guitar amp) is the case. "
>
> Ok - so *how easily* ?
>>
>> >>
>> >> ** The question has been answered.
>> >>
>> >> Do your own tests if you want proof.
>> >>
>> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
>> >> spikes
>> >> "
>> >> for confirmation the phenomenon is well known.
>> >
>> >
>> > So you're just making it up ( you can't or refuse to explain it ).
>>
>> ** What an UTTER non sequitur !!!!!!!!
>
> So go-on, what causes the 5kV ?
** So you have no idea what the term " flyback spikes" refers to ?
But you do now accept that they really exist in valve amps ???
Finally did a little Googling - did we ?
...... Phil
Phil Allison
"Arny Krueger"
> Ironically, if one takes Phil's advice and searches alt.guitar.amps for
> posts about flyback spikes, you find him dodging the same basic question
> you asked about generating 5 Kv spikes around 2/25/2003, for example.
** Massive, silly LIE.
There are no relevant posts there from me around that date.
> Searching further, it looks like people are talking about loose 1/4 plugs,
> and the like. Based on what I know about generating inductive spikes,
** Which is practically nothing.
> a wide range of inductances can suffice, and saying that 8 ohm speakers
> are always safe with a given amp would be a real stretch.
** Which no-body said.
Arny's expertise in arguing fallaciously from an entrenched position of
massive ignorance as good as ever.
....... Phil
Lord Valve
Chris Hornbeck wrote:
> Despite what you may have seen from a loud-mouthed
> know-it-all on this NG, don't worry.
Well, shit-fire and boy howdy, son...
You're wrong, but you can derive some small solace
from the fact that you're wrong for all the right reasons,
chief among them being ignorance regarding actual
field operating conditions for *guitar* amplifiers.
You've also never seen an Epiphone Valve Junior,
nor the schematic thereto. Right?
So - this amp runs a single EL84, giving an output
of around 4 watts RMS. One 12AX7. SS bridge
rectifier for the HV, as well as one for the heaters.
No screen resistor. The entire shebang - including
the speaker - *retails* for $139, and can often be
had for less than $100, brand new in the box. In
short, it's a cheap-ass piece of Chinese shit,
a bare-bones minimum design intended to sell
for the lowest price possible - less, in fact, than
most audiophools spend on a couple of snob-glass
preamp tubes.
Think any corners were cut?
I've had around a half-dozen of these across my
bench in the last year. All but one had the same
problem: fried socket. Cause: "I hooked it up
to my (brand XYZ) speaker cabinet cuz it wasn't
loud enough for me to play with a drummer."
Said speaker cabinet, of course, was nearly
always an 8-ohm box. One was 16.
This is a 4-watt amp commonly purchased by
the worst gear abusers on the planet: guitar
pickers. Since it's only 4 watts, it is *always*
played at full-bore output clipping, for max
distortion and "blues tone." Its (often short)
life is one of maximum stress, placed upon
the sleaziest components imaginable.
Now, son - you may know what you may
know, and it may well be at odds with what
I've said, but I have hands-on time with this
particular gizmo, and I know for certain it
eats tube sockets when operated into a
higher than spec load. If you want to show
me the math which proves that a bumblebee
can't fly, be my guest. I've seen 'em fly, so
I'll take your "knowledge" with a grain of salt,
if that's OK with you. You don't catch my ass
on this NG telling the audiophools about their
SET 300B snob designs for a fairly good
reason: I know jack shit about 'em. The
difference between me and the audiowankers
is that I can admit it.
Lord Valve
Expert Guitar Amp Dude
Eeyore
Phil Allison wrote:
> "Eeysore the Raving CRIMINAL LUNATIC" "
>
> >> " Normal operation ( for a guitar amp) is the case. "
> >
> > Ok - so *how easily* ?
> >>
> >> >> ** The question has been answered.
> >> >>
> >> >> Do your own tests if you want proof.
> >> >>
> >> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
> >> >> spikes
> >> >> "
> >> >> for confirmation the phenomenon is well known.
> >> >
> >> >
> >> > So you're just making it up ( you can't or refuse to explain it ).
> >>
> >> ** What an UTTER non sequitur !!!!!!!!
> >
> > So go-on, what causes the 5kV ?
>
> ** So you have no idea what the term " flyback spikes" refers to ?
I know exactly.
> But you do now accept that they really exist in valve amps ???
If the load's disconnected for sure.
> Finally did a little Googling - did we ?
No need.
Now, how did *YOU* get 5kV flyback spikes.
What was the load ?
How hard was the amp being driven ?
What was the input signal ?
Graham
Eeyore
Phil Allison wrote:
> "Arny Krueger"
>
> > Ironically, if one takes Phil's advice and searches alt.guitar.amps for
> > posts about flyback spikes, you find him dodging the same basic question
> > you asked about generating 5 Kv spikes around 2/25/2003, for example.
>
> ** Massive, silly LIE.
>
> There are no relevant posts there from me around that date.
UTTER BOLLOCKS !
GRaham
Patrick Turner
Lord Valve wrote:
>
> Despite what you may have seen from a couple of
> the know-it-alls on this NG, don't do it. Audiophools
> rarely stress their gear, and consequently rarely
> consider what may happen to it when it is operated
> beyond design parameters - as guitar amplifiers
> *routinely* are. You risk a condition known as high-
> tension flyback if you run a tube guitar amp into a higher
> than rated impedance; this will fry your power tube
> socket, along with the tube in it. Lower-powered
> amps are certainly not immune to this, judging by
> the number of tube sockets I've replaced in Fender
> Champs and small Gibsons over the years. Get
> the correct impedance speaker.
>
> Lord Valve
> Expert
Yes, we hear what you are saying and without any load on the amp
the anode to anode signal voltage can be maybe 2,000Vrms instead of a
maximum
of say 500Vrms with a load of below 20 ohms is at the output.
The majority of guitar amps are set up for maximum power into a load
which is slightly less than what SHOULD be used anyway
so that the typical operation is to have a small amount of class A%
power
in the total class AB power.
So changing from say 4 ohms to 8 ohms is never going to cause a problem
of overloading.
However, the speaker will have a resonant frequency where the Z of the
speaker is very high
at some bass F, and 50+ ohms would not be uncommon, so regardless of
what sort
of speaker is fitted there will be an impedance at bass which is way
above the rated Z
of 4 or 8 ohms which is only valid for the mid F, say at 400Hz.
The inductive nature of the voice coil will have the Z rising at
6dB/octave above a pole
at say 500Hz, so by 5kHz, the speaker Z has gone very high, and as you
know
ppl run their amps with treble and brightness turned right up, so that
the amp is overloaded by HF
before the bass F cause overloading. The resulting distortions are much
favoured by rock'n'rollers,
and when the wave forms become clipped the HF content is even greater,
and there is even more risk of arcing.
So regardless of what you say Lord V, there is always a risk of arcing
at the tube sockets
because there is so little ever done to prevent it, like say
having diodes connected from each anode to ground, to prevent the Vswing
ever moving negative with respect to 0V, and thus prevent Eamax ever
swinging more than twice
the supply voltage.
There is never ever any Zobel network connected across the output so
there is a HF load on the amp.
Guitar amp makers rarely ever do anything to prevent over voltaging the
tube sockets and OPT
insulation because they don't give a shit if an amp blows up because its
going to then need replacing,
and they like the new business, any way they can get it.
So after considering what LV has siad, and has NOT said, and what I have
brought to folk's attention,
I would maintain that changing from a 4 ohm speaker to 8 ohms is OK.
The amount of class A power is increased, although maybe the overall
power is reduced,
which won't alter percieved volume levels much.
The tubes won't be subject to such high peak currents and should perhaps
last a few gigs longer.
Patrick Turner.
Patrick Turner
Ian Iveson wrote:
>
> zyx wrote
>
> >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> >to try it on a 12" speaker which is 8 ohms.
> >
> > Jam away?
>
> A bit risky. Anode voltage may rise higher than some parts can cope
> with reliably.
>
> As a general rule, SS amps don't care too much about a higher load
> impedance, and valves are tolerant of a lower one.
SS amps have a load of NFB and there is a Zobel network which loads the
output,
and there is no OPT, so no high voltages with no load, and supply
voltages are lower anyway,
so risk of arcing in SS amps is not a problem. Sensible SS guitar amps
have diodes from the output to
the rails to prevent swings on the output ever going more than the rail
voltage peak value,
since this can occur with the inductive load of a speaker, and cause
instant death to the output
bjts with reverse flow currents.
Tube guitar amps under discussion don't have any precautions to limit
anode voltage swings way above what happens with 4,8, or 16 ohms.
Low value loads on tube guitar amps means much earlier death for the
tubes,
as evidenced in amps used for heavy metal / grunge band use where the
guitar sound
is a continuous stream of square waves during gross output tube
saturation.
NEVER use a lower than recommended load on a tube amp.
If you do, send the bill for new tubes to Ian who will pay because he
advises its OK.
Patrick Turner.
>
> cheers, Ian
Phil Allison
"Eeysore the FUCKWIT POMMY CUNT "
** Shame how the date is the 19th, not the 25th as stated.
Shame how the issue is not the same one alluded to by Arny.
FUCK the HELL OFF & DIE you POMMY ASS !!
........ Phil
Patrick Turner
Eeyore wrote:
>
> Ian Iveson wrote:
>
> > zyx wrote
> >
> > >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> > >to try it on a 12" speaker which is 8 ohms.
> > >
> > > Jam away?
> >
> > A bit risky. Anode voltage may rise higher than some parts can cope
> > with reliably.
>
> Oh puhleeze ! Is that nonsense or what ?
>
> > As a general rule, SS amps don't care too much about a higher load
> > impedance, and valves are tolerant of a lower one.
>
> Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will
> drive a 1 - 2 ohms load very well, yet many SS amps do it admirably.
>
> Graham
Tube amps can be load matched to allow any low value load to be
connected since there is an OPT which may have adjustable configurations
of windings.
Even many crummy old tube amps had matching for 4 or 16 ohms by
paralleling or seriesing
the two secondary OPT windings. This allowed a range of anything above 2
ohms, because the
4 ohm load may have given a match for class A, and the 2 ohm would be
tolerated
since the load is still an OK class AB load.
The typical low levels used with hi-fi permit some load mismatch, but
not in guitar amp world,
a world of plectrum demons.
SS amps have no such matching OPT or other device, and need current /
voltage limiting.
What is NEVER fitted to an SS amp is an intelligent circuit that detects
if the load
is below 2 ohms and TURNS THE AMP OFF even if it is used at low level.
This safety option would save all the amps who expire when connected to
shorted speaker cables
or to fried/faulty speakers/crossovers.
The makers of SS amps have had 40 years to fit decent active protection
but they
prefer you buy a fucking new amp, rather than have the old one continue
for too long.
Tubes will also glow red and thermal out if the load is too low, but it
just takes longer for it to happen.
If an OPT is destroyed in the process, it can be very expensive!
Patrick Turner.
Phil Allison
"Eeysore the Raving CRIMINAL LUNATIC" "
>> >> " Normal operation ( for a guitar amp) is the case. "
>> >
>> > Ok - so *how easily* ?
>> >>
>> >> >> ** The question has been answered.
>> >> >>
>> >> >> Do your own tests if you want proof.
>> >> >>
>> >> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
>> >> >> spikes
>> >> >> "
>> >> >> for confirmation the phenomenon is well known.
>> >> >
>> >> >
>> >> > So you're just making it up ( you can't or refuse to explain it ).
>> >>
>> >> ** What an UTTER non sequitur !!!!!!!!
>> >
>> > So go-on, what causes the 5kV ?
>>
>> ** So you have no idea what the term " flyback spikes" refers to ?
>
> I know exactly.
>
>
>> But you do now accept that they really exist in valve amps ???
>
> If the load's disconnected for sure.
>
** Err - what about inductive loads ??
Like guitar speaker cabs ??
>> Finally did a little Googling - did we ?
>
> No need.
** But I bet you did so anyhow - LIAR !!
> Now, how did *YOU* get 5kV flyback spikes.
>
> What was the load ?
** A quad box, 4 x Celestion 12 inch, wired series /parallel.
An 8 or 16 ohm dummy load with series inductor of a few mH simulates the
above.
> How hard was the amp being driven ?
** Full overdrive / clipping.
Just like most guitarist play their Marshalls for hours on end.
> What was the input signal ?
** A slide guitarist with his Gibson SG demonstrated in one case.
A sine wave bench gen does nicely too.
BTW :
I don't expect a VILE CRIMINAL LUNATIC
like Graham Stevenson to accept a single word of this.
He did not ask me in order to find out the facts.
Having done NO such tests himself - he has not the SLIGHTEST clue about
it.
He will never do any either.
....... Phil
Eeyore
Patrick Turner wrote:
> Ian Iveson wrote:
> > zyx wrote
> >
> > >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> > >to try it on a 12" speaker which is 8 ohms.
> > >
> > > Jam away?
> >
> > A bit risky. Anode voltage may rise higher than some parts can cope
> > with reliably.
> >
> > As a general rule, SS amps don't care too much about a higher load
> > impedance, and valves are tolerant of a lower one.
>
> SS amps have a load of NFB and there is a Zobel network which loads the
> output, and there is no OPT, so no high voltages with no load, and supply
> voltages are lower anyway,
Not to mention diodes fron output to supply rails too.
Graham
Eeyore
Phil Allison wrote:
> "Eeysore the FUCKWIT POMMY CUNT "
>
> "Arny Krueger"
> >>
> >> > Ironically, if one takes Phil's advice and searches alt.guitar.amps for
> >> > posts about flyback spikes, you find him dodging the same basic
> >> > question
> >> > you asked about generating 5 Kv spikes around 2/25/2003, for example.
> >>
> >> ** Massive, silly LIE.
> >>
> >> There are no relevant posts there from me around that date.
> >
> > UTTER BOLLOCKS !
> >
> > http://groups.google.com/group/alt.guitar.amps/browse_frm/thread/573556099d1bf704/8b2b685575212897?lnk=gst&q=phil+allison+feb+2003&rnum=9#8b2b685575212897
>
> ** Shame how the date is the 19th, not the 25th as stated.
You said " around that date.". Which it is.
15
From: Phil Allison - view profile
Date: Tues, Feb 18 2003 10:08 pm
> Shame how the issue is not the same one alluded to by Arny.
It is exactly......
" ** There are often MAJOR inductive spikes with a nominally **correctly
loaded** amp when run very hard into real speakers or simulated reactive
loads - I have measured up to 5 kV peaks on the tube plates with a 100 W
Marshall with 8 ohms plus 5 mH. "
Graham
Eeyore
Patrick Turner wrote:
> Eeyore wrote:
> > Ian Iveson wrote:
> > > zyx wrote
> > >
> > > >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> > > >to try it on a 12" speaker which is 8 ohms.
> > > >
> > > > Jam away?
> > >
> > > A bit risky. Anode voltage may rise higher than some parts can cope
> > > with reliably.
> >
> > Oh puhleeze ! Is that nonsense or what ?
> >
> > > As a general rule, SS amps don't care too much about a higher load
> > > impedance, and valves are tolerant of a lower one.
> >
> > Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will
> > drive a 1 - 2 ohms load very well, yet many SS amps do it admirably.
> >
> > Graham
>
> Tube amps can be load matched to allow any low value load to be
> connected since there is an OPT which may have adjustable configurations
> of windings.
I had in mind the 'typical' 4, 8 and 16 ohm taps on most power amplifiers.
Have you ever seen a 2 ohm tap btw ?
Graham
Phil Allison
"Eeysore the Fucking Pommy Cunthead "
>
> Patrick Turner wrote:
>
>> SS amps have a load of NFB and there is a Zobel network which loads the
>> output, and there is no OPT, so no high voltages with no load, and supply
>> voltages are lower anyway,
>
> Not to mention diodes fron output to supply rails too.
>
** Ahhh - the diodes are to catch those pesky flyback spikes, yet again.
The ones this ASININE POMMY CUNTHEAD denies exist.
ROTFLMAO !!!
What an absolute hoot this Stevenson Criminal Nutter is !!
....... Phil
Patrick Turner
I suggest that where you have an OPT which has a large amount of
inductance
in its primary, that where the anode current is sharply cut off, as is
the case in an unloaded
pentode amp which is over driven, then there are huge emfs produced
unless these are shunted somehow.
The simplest way to avoid the phenomenon that Phil Allison and myself
and LV say occurs,
is to connect 3 x IN4007 in series from each anode to 0V so that the
diode cathodes are at the tube anodes,
and diode anodes are at 0V.
Under normal use there s no flow in the diodes to 0V, but should a large
back emf
occur, it will try to one end of the OPT primary very +ve while sending
the other end
very -ve, and THEN THE DIODES CONDUCT and this loads the OPT and shunts
the back emf,
thus limiting, or clamping the output T primary voltage.
I have never seen 5,000Vrms in a wayward unloaded OPT, but I can't say
it wouldn't occur.
I have seen many amps suffer from arcing because of the rather highish
ordinary working voltages
including those with B+ rail = 350V and with EL84 etc, but this usually
occurs
because the sockets/underchassis area is polluted, or damp, or the OPT
is dmap after storage
in a damp place for 20 years.
Amps using EL34 with B+ = 900V and Eg2 = 450V are VERY PRONE TO ARCING
between the anode pin 3 and the earthy
heater pin 2 on the octal socket.
807 amps with 600V at the anode top cap and only 300V at Eg2 are less
prone to socket worries
but the OPT is still very prone to arcing if not well insulated or
varnished.
Patrick Turner
Phil Allison
>> "Arny Krueger"
>> >>
>> >> > Ironically, if one takes Phil's advice and searches alt.guitar.amps
>> >> > for
>> >> > posts about flyback spikes, you find him dodging the same basic
>> >> > question
>> >> > you asked about generating 5 Kv spikes around 2/25/2003, for
>> >> > example.
>> >>
>> >> ** Massive, silly LIE.
>> >>
>> >> There are no relevant posts there from me around that date.
>> >
>> > UTTER BOLLOCKS !
>> >
>> > http://groups.google.com/group/alt.guitar.amps/browse_frm/thread/573556099d1bf704/8b2b685575212897?lnk=gst&q=phil+allison+feb+2003&rnum=9#8b2b685575212897
>>
>> ** Shame how the date is the 19th, not the 25th as stated.
>
> You said " around that date." Which it is.
** No - it is 6 days earlier & cannot be in the same thread as Arny is
saying.
>> Shame how the issue is not the same one alluded to by Arny.
>
> It is exactly......
** The post is NOT relevant to the claim Arny's made above.
YOU ASININE, ASD FUCKED IDIOT !!.
........ Phil
Phil Allison
"Patrick Turner"
> The simplest way to avoid the phenomenon that Phil Allison and myself
> and LV say occurs,
** Just wanna make sure this does not go unnoticed.
> is to connect 3 x IN4007 in series from each anode to 0V so that the
> diode cathodes are at the tube anodes,
** Best use high speed diodes.
Watch out for the traps in doing this too.
The exact position of fuses or standby switches in an amp's circuit can make
this idea very un-safe.
........... Phil
Eeyore
Phil Allison wrote:
> "Eeysore the Raving CRIMINAL LUNATIC" "
>
> >> >> " Normal operation ( for a guitar amp) is the case. "
> >> >
> >> > Ok - so *how easily* ?
> >> >>
> >> >> >> ** The question has been answered.
> >> >> >>
> >> >> >> Do your own tests if you want proof.
> >> >> >>
> >> >> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
> >> >> >> spikes
> >> >> >> "
> >> >> >> for confirmation the phenomenon is well known.
> >> >> >
> >> >> >
> >> >> > So you're just making it up ( you can't or refuse to explain it ).
> >> >>
> >> >> ** What an UTTER non sequitur !!!!!!!!
> >> >
> >> > So go-on, what causes the 5kV ?
> >>
> >> ** So you have no idea what the term " flyback spikes" refers to ?
> >
> > I know exactly.
> >
> >
> >> But you do now accept that they really exist in valve amps ???
> >
> > If the load's disconnected for sure.
> >
>
> ** Err - what about inductive loads ??
>
> Like guitar speaker cabs ??
>
> >> Finally did a little Googling - did we ?
> >
> > No need.
>
> ** But I bet you did so anyhow - LIAR !!
I didn't. As I said - simply no need.
> > Now, how did *YOU* get 5kV flyback spikes.
> >
> > What was the load ?
>
> ** A quad box, 4 x Celestion 12 inch, wired series /parallel.
>
> An 8 or 16 ohm dummy load with series inductor of a few mH simulates the
> above.
>
> > How hard was the amp being driven ?
>
> ** Full overdrive / clipping.
>
> Just like most guitarist play their Marshalls for hours on end.
>
> > What was the input signal ?
>
> ** A slide guitarist with his Gibson SG demonstrated in one case.
>
> A sine wave bench gen does nicely too.
So why didn't you just say this when I originally asked ?
> BTW :
>
> I don't expect a VILE CRIMINAL LUNATIC
>
> like Graham Stevenson to accept a single word of this.
>
> He did not ask me in order to find out the facts.
>
> Having done NO such tests himself - he has not the SLIGHTEST clue about
> it.
>
> He will never do any either.
I do accept it. In fact I accepted it when you first posted it if you bother to
check.
What I said in fact was that if you can create 5kV spikes with the *correct*
load, then changing it from 4 to 8 ohms isn't going to change that.
Graham
Eeyore
Patrick Turner wrote:
> What is NEVER fitted to an SS amp is an intelligent circuit that detects
> if the load
> is below 2 ohms and TURNS THE AMP OFF even if it is used at low level.
> This safety option would save all the amps who expire when connected to
> shorted speaker cables
> or to fried/faulty speakers/crossovers.
Actually QSC have a very crude system that does do this.
http://www.freepatentsonline.com/4321554.html
It's an area I've been looking into myself actually as it can hugely benefit
amplifier design by eliminating 'hard' current limiting.
Graham
Arny Krueger
news:519ibpF...@mid.individual.net
> Eeysore the FUCKWIT POMMY CUNT "
>
>
>>> "Arny Krueger"
>>>>>
>>>>>> Ironically, if one takes Phil's advice and searches
>>>>>> alt.guitar.amps for
>>>>>> posts about flyback spikes, you find him dodging the
>>>>>> same basic question
>>>>>> you asked about generating 5 Kv spikes around
>>>>>> 2/25/2003, for example.
>>>>>
>>>>> ** Massive, silly LIE.
>>>>>
>>>>> There are no relevant posts there from me around that
>>>>> date.
>>>>
>>>> UTTER BOLLOCKS !
>>>>
>>>> http://groups.google.com/group/alt.guitar.amps/browse_frm/thread/573556099d1bf704/8b2b685575212897?lnk=gst&q=phil+allison+feb+2003&rnum=9#8b2b685575212897
>>>
>>> ** Shame how the date is the 19th, not the 25th as
>>> stated.
>>
>> You said " around that date." Which it is.
>
>
> ** No - it is 6 days earlier & cannot be in the same
> thread as Arny is saying.
I specified no particular thread, Phil. Time to admit that Graham is right
and you were wrong.
Eeyore
Phil Allison wrote:
None of which has anything to do with loading a 4 ohm tap with 8 ohms.
Graham
Phil Allison
"Eeysore the Raving CRIMINAL LUNATIC" "
>> >> >> " Normal operation ( for a guitar amp) is the case. "
>> >> >
>> >> > Ok - so *how easily* ?
>> >> >>
>> >> >> >> ** The question has been answered.
>> >> >> >>
>> >> >> >> Do your own tests if you want proof.
>> >> >> >>
>> >> >> >> Do a GG search on " alt .guitar.amps" on the topic of
>> >> >> >> "flyback
>> >> >> >> spikes
>> >> >> >> "
>> >> >> >> for confirmation the phenomenon is well known.
>> >> >> >
>> >> >> >
>> >> >> > So you're just making it up ( you can't or refuse to explain
>> >> >> > it ).
>> >> >>
>> >> >> ** What an UTTER non sequitur !!!!!!!!
>> >> >
>> >> > So go-on, what causes the 5kV ?
>> >>
>> >> ** So you have no idea what the term " flyback spikes" refers to ?
>> >
>> > I know exactly.
>> >
>> >
>> >> But you do now accept that they really exist in valve amps ???
>> >
>> > If the load's disconnected for sure.
>> >
>>
>> ** Err - what about inductive loads ??
>>
>> Like guitar speaker cabs ??
>>
>> >> Finally did a little Googling - did we ?
>> >
>> > No need.
>>
>> ** But I bet you did so anyhow - LIAR !!
>
> I didn't. As I said - simply no need.
** Blatant LIE !!
>> > Now, how did *YOU* get 5kV flyback spikes.
>> >
>> > What was the load ?
>>
>> ** A quad box, 4 x Celestion 12 inch, wired series /parallel.
>>
>> An 8 or 16 ohm dummy load with series inductor of a few mH simulates the
>> above.
>>
>> > How hard was the amp being driven ?
>>
>> ** Full overdrive / clipping.
>>
>> Just like most guitarist play their Marshalls for hours on end.
>>
>> > What was the input signal ?
>>
>> ** A slide guitarist with his Gibson SG demonstrated in one case.
>>
>> A sine wave bench gen does nicely too.
>
> So why didn't you just say this when I originally asked ?
** I did say, over and over, it was with a speaker cab and normal guitar amp
use.
You never asked specific, defined questions previously.
Only ones full of ambiguity and smartarse.
>> BTW :
>>
>> I don't expect a VILE CRIMINAL LUNATIC
>>
>> like Graham Stevenson to accept a single word of this.
>>
>> He did not ask me in order to find out the facts.
>>
>> Having done NO such tests himself - he has not the SLIGHTEST clue about
>> it.
>>
>> He will never do any either.
>
> I do accept it. In fact I accepted it when you first posted it if you
> bother to
> check.
** Then decided to contradict it like all hell - eg:
" But you do now accept that they really exist in valve amps ???
If the load's disconnected for sure. "
> What I said in fact was that if you can create 5kV spikes with the
> *correct*
> load, then changing it from 4 to 8 ohms isn't going to change that.
** Which is WRONG.
It *does* change things and often for the worse.
Depends on specific and individual cases whether a failure will occur.
I have already answered you on this.
The POINT is that ALL guitar amps that suffer from large voltage " flyback
spikes" are an accident just waiting to happen.
....... Phil
Eeyore
Phil Allison wrote:
> Eeysore the FUCKWIT POMMY CUNT "
>
> >> "Arny Krueger"
> >> >>
> >> >> > Ironically, if one takes Phil's advice and searches alt.guitar.amps
> >> >> > for posts about flyback spikes, you find him dodging the same basic
> >> >> > question you asked about generating 5 Kv spikes around 2/25/2003,
> >> >> > for example.
> >> >>
> >> >> ** Massive, silly LIE.
> >> >>
> >> >> There are no relevant posts there from me around that date.
> >> >
> >> > UTTER BOLLOCKS !
> >> > http://groups.google.com/group/alt.guitar.amps/browse_frm/thread/573556099d1bf704/8b2b685575212897?lnk=gst&q=phil+allison+feb+2003&rnum=9#8b2b685575212897
> >>
> >> ** Shame how the date is the 19th, not the 25th as stated.
> >
> > You said " around that date." Which it is.
>
> ** No - it is 6 days earlier & cannot be in the same thread as Arny is
> saying.
The date is close enough for me and the thread was about exactly the same topic we're discussing here !
Why on earth would you want to deny it ?
Graham
Phil Allison
"Arny Krueger"
" Ironically, if one takes Phil's advice and searches alt.guitar.amps for
posts about flyback spikes, you find him dodging the same basic question you
asked about generating 5 Kv spikes around 2/25/2003, for example. "
>> ** No - it is 6 days earlier & cannot be in the same
>> thread as Arny is saying.
>
>
> I specified no particular thread, Phil.
** You specified a date and a * particular * line of content.
Both are missing in that link.
Where the FUCK is it ??
Were you LYING or just totally WRONG as USUAL ???
> Time to admit that Graham is right and you were wrong.
** Go get totally FUCKED
you MONSTROUSLY EVIL HYPOCRITE
........ Phil
Phil Allison
** Not the claim of yours at issue.
As you very well know.
........ Phil
Eeyore
Phil Allison wrote:
> "Eeysore the Raving CRIMINAL LUNATIC" "
> >
> > So why didn't you just say this when I originally asked ?
>
> ** I did say, over and over, it was with a speaker cab and normal guitar amp
> use.
Rubbish, you only just posted that answer once about half an hour ago.
Anyone looking at the time stamps on the posts can see that for themselves.
> You never asked specific, defined questions previously.
They were perfectly clear !
> Only ones full of ambiguity and smartarse.
And how exactly is that any different from you ? Weren't you smart enough to
understand my question ?
Graham
Phil Allison
** No, the date and the thread need to match up with Arny's claim above in
order for it to be true.
There is no post from me, at any time, that matches up.
Arny was obfuscating & bullshitting - as bloody usual.
....... Phil
Eeyore
Phil Allison wrote:
Show where I claimed anything else.
> As you very well know.
No. It was you who brought up the *off-topic* issue of 5kV spikes with *correct*
loading.
Graham
Phil Allison
"Eeysore the Raving CRIMINAL LUNATIC" "
>> > So why didn't you just say this when I originally asked ?
>>
>> ** I did say, over and over, it was with a speaker cab and normal guitar
>> amp
>> use.
>
> Rubbish, you only just posted that answer once about half an hour ago.
** INSANE CRAPOLOGY !
This post was 10.5 hours ago.
" Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV spikes
on the output plates when operating into a speaker cab. "
** This was only 44 mins later:
" Normal operation ( for a guitar amp) is the case. "
** Then, 7 hours ago, I combined them for you:
" Eg, any Marshall valve amp can easily be made to exhibit +/- 5 kV
spikes on the output plates when operating into a speaker cab.
LVs phrase " high tension flyback " is a very apt one - cos it don't
happen with a resistive load. "
" Normal operation ( for a guitar amp) is the case. "
> Anyone looking at the time stamps on the posts can see that for
> themselves.
** See CLEARLY what a damn INSANE LIAR you are !!!
....... Phil
Phil Allison
"Eeysore the Fucking Pommy Cunthead "
>>>
>> >> ** Ahhh - the diodes are to catch those pesky flyback spikes, yet
>> >> again.
>> >>
>> >> The ones this ASININE POMMY CUNTHEAD denies exist.
>> >>
>> >> ROTFLMAO !!!
>> >>
>> >> What an absolute hoot this Stevenson Criminal Nutter is !!
>> >
>> > None of which has anything to do with loading a 4 ohm tap with 8 ohms.
>>
>>
>> ** Not the claim of yours at issue.
>
> Show where I claimed anything else.
** Here it is:
" Utter garbage. The voltage swings on the primary of the output transformer
are typically well *under* a thousand
volts. They cannot in any case exceed 2 x B+ in normal operation. "
Denies the existence of flyback spikes, even in guitar amps.
> No. It was you who brought up the *off-topic* issue of 5kV spikes with
> *correct*
> loading.
** LV mentioned " high tension flyback" .
I quoted this remark in my first post.
Then gave some actual figures.
Not OT in the slightest.
You PITA fucking Dim Wit.
........ Phil
Sander deWaal
>There are only 2 professional designers here and they are Patrick Turmer and myself.
Oh? Just the 2 of you?
;-)
>Lord Valve is a very experienced tube expert at the practical level but has no design experience AFAIK.
Repair experience is probably even more useful, one gets to see all
different kinds of amps, topologies and failures.
One can get a very good insight about the weak spots in designs by a
lifelong career in repairing various audio gear.
At least, that's where I came from.
And I still do repair every now and then, of MI and SR amps, domestic
audio and studio gear.
I would take LV's advice about tubes and guitar amps over anyone elses
every day, despite the fact that we're hardly friends.
--
- Maggies are an addiction for life. -
Sander deWaal
>Have you ever seen a 2 ohm tap btw ?
Yes.
My own OPTs have 2.83 ohm taps, in fact.
I use them to drive 2 paralleled Magnepans per channel.
Lord Valve
The RAT's ass mumbled:
> > > Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will
> > > drive a 1 - 2 ohms load very well, yet many SS amps do it admirably.
> > >
> > > Graham
> >
> > Tube amps can be load matched to allow any low value load to be
> > connected since there is an OPT which may have adjustable configurations
> > of windings.
>
> I had in mind the 'typical' 4, 8 and 16 ohm taps on most power amplifiers.
>
> Have you ever seen a 2 ohm tap btw ?
Where ya been, junior?
Two of the "Holy Grail of Tone" amps - the Fender '59
Tweed Bassman and the Fender '65 blackface Super
Reverb - have 2-ohm outputs. (So does the famous
Ampeg SVT, designed to drive one or two 4-ohm
cabinets containing eight 10" 32-ohm speakers
wired in parallel, with a switching jack for selecting
the 2-ohm tap when two cabinets are used. Try running
one of those into an upward mismatch - 8 ohm box
on the 4-ohm tap - and watch the fireworks.) Both of the
Fender amps drive four 10" 8-ohm speakers wired in parallel.
A few times a year - *every* year since I have been repairing
guitar amps, and that would be about 40 of 'em <years>)
I've had to fix several of these amps which had the
speaker wiring "corrected" to the much more common
series-parallel arrangement that produces an 8-ohm
load from four 8-ohm speakers. Said "correction"
usually performed by some audiophool "expert"
who "knew" that tube amps don't drive 2-ohm
loads. Of course, as soon as this "repair" was
accomplished, the poor bastard's amp started
blowing fuses. Seems the sockets were arced.
Imagine that.
Lord Valve
Expert
John Byrns
Patrick Turner <in...@turneraudio.com.au> wrote:
> SS amps have a load of NFB and there is a Zobel network which loads the
> output,
> and there is no OPT, so no high voltages with no load, and supply
> voltages are lower anyway,
> so risk of arcing in SS amps is not a problem. Sensible SS guitar amps
> have diodes from the output to
> the rails to prevent swings on the output ever going more than the rail
> voltage peak value,
> since this can occur with the inductive load of a speaker, and cause
> instant death to the output
> bjts with reverse flow currents.
I have had that happen in an amp without the diodes you mention. When
it went it made quite a show, the transistors were in TO-3 packages and
when it went one stated arcing between the emitter post inside and the
top of the package. The arc cut a hole through the top of the package
and started blasting out a jet of hot metal and flame sort of like some
sort of plasma torch, until I killed the power.
Regards,
John Byrns
--
Surf my web pages at, http://fmamradios.com/
John Byrns
Patrick Turner <in...@turneraudio.com.au> wrote:
> So regardless of what you say Lord V, there is always a risk of arcing
> at the tube sockets
> because there is so little ever done to prevent it, like say
> having diodes connected from each anode to ground, to prevent the Vswing
> ever moving negative with respect to 0V, and thus prevent Eamax ever
> swinging more than twice
> the supply voltage.
You are assuming the transformer has no leakage inductance between
primary halves, is this a valid assumption for the typical guitar amp?
Iain Churches
"Eeyore" <rabbitsfriend...@hotmail.com> wrote in message
news:45AF9254...@hotmail.com...
Yep. I have an amp on my bench with a stock Sowter UK transformer.
The secondary windings can be connected in series and in parallel for
1,4,8, and 16 Ohms.
Iain
>
> Graham
>
zyx
"Sander deWaal" <nos...@wanadoo.nl> wrote in message
news:r5avq2pm6rk06b5ja...@4ax.com...
Thanks for your honesty and I think I'll trust LV's advices. I remember long
ago that the tubes have speakers rated at 3.2 ohms. 4 ohms sure ain't far
from that.
Now another question. Can this little 5 watt single ended class A amp (12ax7
and el84) drive a 2x12 speakers? I believe wiring two 8 ohm speakers in
parallel will give me 4 ohms?
Eeyore
zyx wrote:
> "Sander deWaal" <nos...@wanadoo.nl> wrote in message
> > Eeyore <rabbitsfriend...@hotmail.com> said:
> >
> >>There are only 2 professional designers here and they are Patrick Turmer
> >>and myself.
> >
> > Oh? Just the 2 of you?
> >
> > ;-)
> >
> >>Lord Valve is a very experienced tube expert at the practical level but
> >>has no design experience AFAIK.
> >
> >
> > Repair experience is probably even more useful, one gets to see all
> > different kinds of amps, topologies and failures.
> >
> > One can get a very good insight about the weak spots in designs by a
> > lifelong career in repairing various audio gear.
> > At least, that's where I came from.
> > And I still do repair every now and then, of MI and SR amps, domestic
> > audio and studio gear.
> >
> > I would take LV's advice about tubes and guitar amps over anyone elses
> > every day, despite the fact that we're hardly friends.
> >
> >
> > - Maggies are an addiction for life. -
>
> Thanks for your honesty and I think I'll trust LV's advices. I remember long
> ago that the tubes have speakers rated at 3.2 ohms. 4 ohms sure ain't far
> from that.
>
> Now another question. Can this little 5 watt single ended class A amp (12ax7
> and el84) drive a 2x12 speakers?
Their physical size is unimportant from the perspective of whether the amp can
drive them.
You will however miss out on any colouration that you might typically associate
with such speakers though.
Guitar amplification often relies strongly on exploiting the technical
'shortcomings' of traditional amplification equipment in an 'artistic' way. The
speakers themselves play a part in this with their 'overdriven' sound. You won't
be overdriving a 12" speaker with 2-3 watts though.
> I believe wiring two 8 ohm speakers in parallel will give me 4 ohms?
It will indeed.
Graham
Chris Hornbeck
wrote:
>> Despite what you may have seen from a loud-mouthed
>> know-it-all on this NG, don't worry.
>
>Well, shit-fire and boy howdy, son...
First of all, let me apologize for what, last night,
seemed like a funny play on your larger-than-life
reputation, but today just reads as awful. You're
a real gentleman to have let it slide so easily.
>You're wrong, but you can derive some small solace
>from the fact that you're wrong for all the right reasons,
>chief among them being ignorance regarding actual
>field operating conditions for *guitar* amplifiers.
>
>You've also never seen an Epiphone Valve Junior,
>nor the schematic thereto. Right?
Spent more than three decades doing bench repairs, but
fortunately never met these Chinese Firecracker Champs.
That you're having to repair 'em at all makes me
wonder if the repairs are on your dime - my heart
goes out to ya either way. Lotta work for little return.
It's too late to fix their design issues, but it'd be
interesting to know how the external speakers connect.
Speaker cabs are wired several different ways. Do these
connect the external speakers in parallel with the internal
or do the jacks disconnect the internal speaker? Is
the jack make-before-break? They could even be connected
in series. God dwells in the details.
You're obviously seeing a real issue here, but I'll have
to stand by my statement that the nominal speaker impedance
is the wrong place to be looking. Uhh... I think.
Much thanks, as always,
Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau
Phil Allison
"Sander deWaal"
>
> Repair experience is probably even more useful, one gets to see all
> different kinds of amps, topologies and failures.
>
> One can get a very good insight about the weak spots in designs by a
> lifelong career in repairing various audio gear.
** But ONLY if that technician is * insatiably curious* about audio
electronics and puts in the time and considerable mental effort to analyse
nearly every circuit & component failure scenario they come across.
The vast majority of service techs are not allowed ( even if they wanted to)
to indulge in such time consuming, non profit making activity when there is
other work waiting to be done and a prowling boss to keep happy.
Only independent, self employed techs who are not too overworked might do as
you suggest, even then only if they have the required technical ability.
The typical product design engineer never gets involved with repairs, even
to his own designs, gets little or no feedback from the field unless a very
serious failure situation arises. They are normally quite unwilling to
accept any input or criticism from ANY folk involved in the repair business
and especially not from other designers.
This of course condemns them to repeating their dumbest mistakes - which
are then mass produced, sold to a gullible marketplace and ultimately left
to mere repair techs to eventually unravel & attempt to find fixes for.
I have many times wished I could deliver some expensive pile of audio
garbage back to the doorstep of the utter ass who is responsible for it and
say - " you designed this POS - so you bloody fix it " !!
....... Phil
BobFli...@nospamno.com
wrote:
Excellent post, Phil, I congratulate you.
As a "repair tech" I've always been amazed at the crap some engineers can come
up with... at the same time, impressed with the bullet proof designs of others.
And I've used my experience to design lots of equipment over the years - I use
the "empirical design and idea theft" methods, picking the best circuits I've
seen and modifying them to suit my needs.
I would sooner follow an experienced independent tech then an unknown engineer
any day.
Ian Iveson
>>The typical product design engineer never gets involved with
>>repairs, even to his own designs, gets little or no feedback from
>>the field unless a very serious failure situation arises. They are
>>normally quite unwilling to accept any input or criticism from ANY
>>folk involved in the repair business and especially not from other
>>designers.
>>
Not typical in my experience.
Within the larger manufacturing companies, the relationships between
production engineering, research and development, and quality
assurance are pretty much standard and optimised. In general, you
won't find a problem that they don't already know about in minute
detail.
Unreliable or defective products are shipped for all sorts of
structural reasons: inertia, internal politics, cash flow
requirements, etc.
Also, for the general consumer market, most new products will be
sensibly designed to equal the accepted standards of reliability set
by producers as a whole. The higher cost of producing a more reliable
product can't be handed down to consumers who aren't willing to pay.
Nevertheless, modern mass-produced consumer products, particularly
electronics, have hugely reduced the cost of reliability.
cheers, Ian
Phil Allison
"Ian Iveson Colossal Fuckwit "
>
>>>The typical product design engineer never gets involved with repairs,
>>>even to his own designs, gets little or no feedback from the field
>>>unless a very serious failure situation arises. They are normally quite
>>>unwilling to accept any input or criticism from ANY folk involved in the
>>>repair business and especially not from other designers.
>>>
>
> Not typical in my experience.
** You do not have any - you stinking ASD fucked LIAR.
> Within the larger manufacturing companies, the relationships between
> production engineering, research and development, and quality assurance
> are pretty much standard and optimised.
** Completely and UTTERLY beside the point.
Iveson is totally illiterate.
....... Phil
Ian Iveson
Phil Allison wrote
>>>>The typical product design engineer never gets involved with
>>>>repairs, even to his own designs, gets little or no feedback from
>>>>the field unless a very serious failure situation arises. They are
>>>>normally quite unwilling to accept any input or criticism from ANY
>>>>folk involved in the repair business and especially not from other
>>>>designers.
>> Not typical in my experience.
>
>
> ** You do not have any - you stinking ASD fucked LIAR.
ASD?
You know nothing about what I do, or what I have done, for a living.
I'm happy with your ignorance. I said "in my experience" in order to
qualify "typical".
Your idea of typical is only within your experience, too. You have
experience of grubby back-street tinkering. I can understand why you
feel bitter, but you are barking up the wrong tree.
>> Within the larger manufacturing companies, the relationships
>> between production engineering, research and development, and
>> quality assurance are pretty much standard and optimised.
>
>
> ** Completely and UTTERLY beside the point.
You missed the last sentence of the paragraph, which explained the
link, silly. And the other paragraphs which clarified it.
Let me make it a bit clearer. In my experience, and to my knowledge,
the typical designer doesn't need you. There is adequate provision
within the organisation to ensure that designers are aware of the
performance of their designs in the field.
> > Iveson is totally illiterate.
Not totally. Slightly, sometimes. Takes me a while to do the
crossword, but I get there in the end.
love and kisses, Ian
Patrick Turner
Lord Valve wrote:
>
> Chris Hornbeck wrote:
>
> > Despite what you may have seen from a loud-mouthed
> > know-it-all on this NG, don't worry.
>
> Well, shit-fire and boy howdy, son...
>
> You're wrong, but you can derive some small solace
> from the fact that you're wrong for all the right reasons,
> chief among them being ignorance regarding actual
> field operating conditions for *guitar* amplifiers.
>
> You've also never seen an Epiphone Valve Junior,
> nor the schematic thereto. Right?
>
> So - this amp runs a single EL84, giving an output
> of around 4 watts RMS. One 12AX7. SS bridge
> rectifier for the HV, as well as one for the heaters.
> No screen resistor. The entire shebang - including
> the speaker - *retails* for $139, and can often be
> had for less than $100, brand new in the box. In
> short, it's a cheap-ass piece of Chinese shit,
> a bare-bones minimum design intended to sell
> for the lowest price possible - less, in fact, than
> most audiophools spend on a couple of snob-glass
> preamp tubes.
>
> Think any corners were cut?
>
> I've had around a half-dozen of these across my
> bench in the last year. All but one had the same
> problem: fried socket. Cause: "I hooked it up
> to my (brand XYZ) speaker cabinet cuz it wasn't
> loud enough for me to play with a drummer."
> Said speaker cabinet, of course, was nearly
> always an 8-ohm box. One was 16.
>
> This is a 4-watt amp commonly purchased by
> the worst gear abusers on the planet: guitar
> pickers. Since it's only 4 watts, it is *always*
> played at full-bore output clipping, for max
> distortion and "blues tone." Its (often short)
> life is one of maximum stress, placed upon
> the sleaziest components imaginable.
>
> Now, son - you may know what you may
> know, and it may well be at odds with what
> I've said, but I have hands-on time with this
> particular gizmo, and I know for certain it
> eats tube sockets when operated into a
> higher than spec load. If you want to show
> me the math which proves that a bumblebee
> can't fly, be my guest. I've seen 'em fly, so
> I'll take your "knowledge" with a grain of salt,
> if that's OK with you. You don't catch my ass
> on this NG telling the audiophools about their
> SET 300B snob designs for a fairly good
> reason: I know jack shit about 'em. The
> difference between me and the audiowankers
> is that I can admit it.
>
> Lord Valve
> Expert Guitar Amp Dude
Lordy Lord. I agree mostly.
But the failures when speakers are changed from 8 to 16 ohms isn't
why it fails; failures due to arcing is gonna happen anyway
since a speaker presents a high Z at each siode of its power range, and
chinese crapologists dunno how to make good shit.
And the chinese dunno what they are doing except they try to copy shit
and
finish up with shittier shit that you can poke a stick at.....
They make 'Goochi' handbags for sheilas, 'Rolecks' watches for the
un-wary,
and any fucken thing goes as long as some poor bastard buys it.
Patrick Turner.
Patrick Turner
Eeyore wrote:
>
> Phil Allison wrote:
>
> > "Eeysore the Raving CRIMINAL LUNATIC" "
> >
> > >> " Normal operation ( for a guitar amp) is the case. "
> > >
> > > Ok - so *how easily* ?
> > >>
> > >> >> ** The question has been answered.
> > >> >>
> > >> >> Do your own tests if you want proof.
> > >> >>
> > >> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
> > >> >> spikes
> > >> >> "
> > >> >> for confirmation the phenomenon is well known.
> > >> >
> > >> >
> > >> > So you're just making it up ( you can't or refuse to explain it ).
> > >>
> > >> ** What an UTTER non sequitur !!!!!!!!
> > >
> > > So go-on, what causes the 5kV ?
> >
> > ** So you have no idea what the term " flyback spikes" refers to ?
>
> I know exactly.
>
> > But you do now accept that they really exist in valve amps ???
>
> If the load's disconnected for sure.
>
> > Finally did a little Googling - did we ?
>
> No need.
>
> Now, how did *YOU* get 5kV flyback spikes.
>
> What was the load ?
>
> How hard was the amp being driven ?
>
> What was the input signal ?
>
> Graham
Graham, no need to react against Allison's poor manners which are a
response to your
inability to understand that perhaps 5,000V is possible in a guitar amp
without a load.
Try measuring one, and you will find out all about.
Very much higher signal voltages anode to anode ARE generated by an
unloaded pentode/beam tetrode
output stage than the normal working loaded voltages.
Patrick Turner.
Patrick Turner
Eeyore wrote:
>
> Patrick Turner wrote:
>
> > Ian Iveson wrote:
> > > zyx wrote
> > >
> > > >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> > > >to try it on a 12" speaker which is 8 ohms.
> > > >
> > > > Jam away?
> > >
> > > A bit risky. Anode voltage may rise higher than some parts can cope
> > > with reliably.
> > >
> > > As a general rule, SS amps don't care too much about a higher load
> > > impedance, and valves are tolerant of a lower one.
> >
> > SS amps have a load of NFB and there is a Zobel network which loads the
> > output, and there is no OPT, so no high voltages with no load, and supply
> > voltages are lower anyway,
>
> Not to mention diodes fron output to supply rails too.
>
> Graham
But I went on to say how inductive speaker loads on an SS amp could give
rise to destructive back emfs.
SS amps need all the protection they can get.
Patrick Turner.
Patrick Turner
Eeyore wrote:
>
> Patrick Turner wrote:
>
> > Eeyore wrote:
> > > Ian Iveson wrote:
> > > > zyx wrote
> > > >
> > > > >I have an epi valve jr combo with 8" speaker that is 4 ohms. I want
> > > > >to try it on a 12" speaker which is 8 ohms.
> > > > >
> > > > > Jam away?
> > > >
> > > > A bit risky. Anode voltage may rise higher than some parts can cope
> > > > with reliably.
> > >
> > > Oh puhleeze ! Is that nonsense or what ?
> > >
> > > > As a general rule, SS amps don't care too much about a higher load
> > > > impedance, and valves are tolerant of a lower one.
> > >
> > > Tolerant to a point ! I wouldn't advise it. In fact I doubt any valve amps will
> > > drive a 1 - 2 ohms load very well, yet many SS amps do it admirably.
> > >
> > > Graham
> >
> > Tube amps can be load matched to allow any low value load to be
> > connected since there is an OPT which may have adjustable configurations
> > of windings.
>
> I had in mind the 'typical' 4, 8 and 16 ohm taps on most power amplifiers.
>
> Have you ever seen a 2 ohm tap btw ?
>
> Graham
What I said in my other posts on the subject was that many old amps have
a pair of
2 ohm windings. When seriesed, you get a match for 8 ohms, because there
are twice the turns on the sec,
and 2 squared = 4, so 2 ohms becomes 8 ohms.
When paralleled, you still only get 2 ohms, since there is no difference
to the turn count.
But many old amps were meant for 4 or 16 ohms by juggling the two lousy
windings offered.
It was either 4 or 16, and having 8 ohms meant the windings had to be
divided awkwardly, and awkward extra
matches cost extra money, so it rarely happened properly.
The 4 or 16 was for for NOMINAL MATCHES of course, never literally,
and usually the nominal meant you had 10k : 16 ohms for 20 watts of
class A, or for anything over
8 ohms for class AB, or 10K : 4 ohms, for class A, or for anything
between 2 and 4 giving acceptable class AB.
To repeat, the 16 ohms configuration meant you could possibly have 5k
a-a : 8 ohms for class AB,
or if the 8 ohms was connected to the two paralleled 4 ohm windings
you'd get 20k a-a as the load,
and a "low distortion, low power class A connection, with low output
resistance".
You could connect 4 ohms to the 4 ohm config for class A but 2 ohms
worked fine since the a-a
load only dropped to 5k a-a, and still drivable by an average pair of
6L6/KT66;
;if more power into lower loads is needed use KT88/KT90.
The OPT is a like an electronic gear box which allows you to drive up
any hill no matter how steep.
Remember the fundementals.
More basic/not so basic info is at http://www.turneraudio.com.au
Patrick Turner.
Patrick Turner
Eeyore wrote:
>
> Phil Allison wrote:
>
> > "Eeysore the Raving CRIMINAL LUNATIC" "
> >
> > >> >> " Normal operation ( for a guitar amp) is the case. "
> > >> >
> > >> > Ok - so *how easily* ?
> > >> >>
> > >> >> >> ** The question has been answered.
> > >> >> >>
> > >> >> >> Do your own tests if you want proof.
> > >> >> >>
> > >> >> >> Do a GG search on " alt .guitar.amps" on the topic of "flyback
> > >> >> >> spikes
> > >> >> >> "
> > >> >> >> for confirmation the phenomenon is well known.
> > >> >> >
> > >> >> >
> > >> >> > So you're just making it up ( you can't or refuse to explain it ).
> > >> >>
> > >> >> ** What an UTTER non sequitur !!!!!!!!
> > >> >
> > >> > So go-on, what causes the 5kV ?
> > >>
> > >> ** So you have no idea what the term " flyback spikes" refers to ?
> > >
> > > I know exactly.
> > >
> > >
> > >> But you do now accept that they really exist in valve amps ???
> > >
> > > If the load's disconnected for sure.
> > >
> >
> > ** Err - what about inductive loads ??
> >
> > Like guitar speaker cabs ??
> >
> > >> Finally did a little Googling - did we ?
> > >
> > > No need.
> >
> > ** But I bet you did so anyhow - LIAR !!
>
> I didn't. As I said - simply no need.
>
> > > Now, how did *YOU* get 5kV flyback spikes.
> > >
> > > What was the load ?
> >
> > ** A quad box, 4 x Celestion 12 inch, wired series /parallel.
> >
> > An 8 or 16 ohm dummy load with series inductor of a few mH simulates the
> > above.
> >
> > > How hard was the amp being driven ?
> >
> > ** Full overdrive / clipping.
> >
> > Just like most guitarist play their Marshalls for hours on end.
> >
> > > What was the input signal ?
> >
> > ** A slide guitarist with his Gibson SG demonstrated in one case.
> >
> > A sine wave bench gen does nicely too.
>
> So why didn't you just say this when I originally asked ?
>
> > BTW :
> >
> > I don't expect a VILE CRIMINAL LUNATIC
> >
> > like Graham Stevenson to accept a single word of this.
> >
> > He did not ask me in order to find out the facts.
> >
> > Having done NO such tests himself - he has not the SLIGHTEST clue about
> > it.
> >
> > He will never do any either.
>
> I do accept it. In fact I accepted it when you first posted it if you bother to
> check.
>
> What I said in fact was that if you can create 5kV spikes with the *correct*
> load, then changing it from 4 to 8 ohms isn't going to change that.
Without any load connected, perhaps 5kV spikes are possible.
With loading of say 20 ohms on an amp with 5k:8 ZR ratio, it is
impossible to have such HV spikes.
Loading the amp DOES change the ability of the amp to make 5 kV spikes.
Measure and observe an amp Graham, and all will be revealed....
Be careful how you measure the HV, lest you blow crap out of your
voltmeter.
Patrick Turner.
> Graham
Patrick Turner
Eeyore wrote:
>
> Patrick Turner wrote:
>
> > What is NEVER fitted to an SS amp is an intelligent circuit that detects
> > if the load
> > is below 2 ohms and TURNS THE AMP OFF even if it is used at low level.
> > This safety option would save all the amps who expire when connected to
> > shorted speaker cables
> > or to fried/faulty speakers/crossovers.
>
> Actually QSC have a very crude system that does do this.
> http://www.freepatentsonline.com/4321554.html
What is the URL for the schematic?
Patrick Turner.
>
> It's an area I've been looking into myself actually as it can hugely benefit
> amplifier design by eliminating 'hard' current limiting.
>
> Graham
Patrick Turner
John Byrns wrote:
>
> In article <45AF89A4...@turneraudio.com.au>,
> Patrick Turner <in...@turneraudio.com.au> wrote:
>
> > So regardless of what you say Lord V, there is always a risk of arcing
> > at the tube sockets
> > because there is so little ever done to prevent it, like say
> > having diodes connected from each anode to ground, to prevent the Vswing
> > ever moving negative with respect to 0V, and thus prevent Eamax ever
> > swinging more than twice
> > the supply voltage.
>
> You are assuming the transformer has no leakage inductance between
> primary halves, is this a valid assumption for the typical guitar amp?
The leakage inductance between halves of guitar amp OPTs is usually
high, but
nevertheless the negative going voltages which are shunted are arrested
by the diodes, and the positive going
voltages at the other end of the primary are also arrested..
And BTW, really high power tube amps for say 1,000 watts+ using
anode supply voltages of say 2.5kV and high ohm anode loads used spark
gaps adjusted so excess voltage would be
harmlessly shunted in a spark. Usually OPT were mounted in a sealed box
full of oil with ceramic stand off connections.
This does not appear in Fender or Marshall.
Back emfs are a fact of life...
Patrick Turner.
Eeyore
Phil Allison wrote:
> The typical product design engineer never gets involved with repairs, even
> to his own designs, gets little or no feedback from the field unless a very
> serious failure situation arises. They are normally quite unwilling to
> accept any input or criticism from ANY folk involved in the repair business
> and especially not from other designers.
That must make me very different then.
I positively ecourage feedback from service guys.
Graham
Eeyore
Patrick Turner wrote:
I had no problem understanding the issue with no load !
His assertion was that you can get 5000V spikes wuith the *correct rated
impedance connected*.
> Try measuring one, and you will find out all about.
>
> Very much higher signal voltages anode to anode ARE generated by an
> unloaded pentode/beam tetrode
> output stage than the normal working loaded voltages.
This wasn't about *unloaded* working Patrick.
Graham
Eeyore
Patrick Turner wrote:
That was what I said myself.
> Loading the amp DOES change the ability of the amp to make 5 kV spikes.
>
> Measure and observe an amp Graham, and all will be revealed....
No need. I've been in agreement with you all along.
> Be careful how you measure the HV, lest you blow crap out of your
> voltmeter.
You'd need a scope to see the flyback spikes not a voltmeter.
Graham
Eeyore
Patrick Turner wrote:
I don't think they're *inherently* any more fragile to be honest.
Graham
Eeyore
Patrick Turner wrote:
> Eeyore wrote:
> >
> > Patrick Turner wrote:
> >
> > > What is NEVER fitted to an SS amp is an intelligent circuit that detects
> > > if the load
> > > is below 2 ohms and TURNS THE AMP OFF even if it is used at low level.
> > > This safety option would save all the amps who expire when connected to
> > > shorted speaker cables
> > > or to fried/faulty speakers/crossovers.
> >
> > Actually QSC have a very crude system that does do this.
> > http://www.freepatentsonline.com/4321554.html
>
> What is the URL for the schematic?
and click on images.
Graham
tubegarden
Eeyore wrote:
>
> I positively ecourage feedback from service guys.
>
> Graham
Hi RATs!
Good plan :) Not everyone can spec the only noisey resistor ever
manufactured ... I am not surprised you didn't notice :^P
Happy Ears!
Al
Phil Allison
"Ian Iveson = INSANE POMMY PRICK "
** This insanely demented, criminal pommy CUNT needs shooting.
........ Phil
Phil Allison
"Eeysore the FUCKWIT POMMY CUNT "
>> The typical product design engineer never gets involved with repairs,
>> even
>> to his own designs, gets little or no feedback from the field unless a
>> very
>> serious failure situation arises. They are normally quite unwilling to
>> accept any input or criticism from ANY folk involved in the repair
>> business
>> and especially not from other designers.
>
> That must make me very different then.
** ROTFL !!!
YOU are the VERY WORST example on earth.
An utterly manic, know nothing, ASD fucked, criminal pommy psychopath &
blatant charlatan.
Jail is where Graham Stevenson should be.
....... Phil
Sander deWaal
>"Sander deWaal"
>....... Phil
Agreed in full, Phil.
I must have been lucky for over 25 years, because I always managed to
learn something from the repairs I did, and it proved extremely useful
in my design career.
--
Arny Krueger
news:519k97F...@mid.individual.net
> "Arny Krueger"
>
>
> " Ironically, if one takes Phil's advice and searches
> alt.guitar.amps for posts about flyback spikes, you find
> him dodging the same basic question you asked about
> generating 5 Kv spikes around 2/25/2003, for example. "
>
>>> ** No - it is 6 days earlier & cannot be in the same
>>> thread as Arny is saying.
>>
>>
>> I specified no particular thread, Phil.
>
>
> ** You specified a date and a * particular * line of
> content.
No, I specified a range of dates and a general line of content.