OT: power conversion
Dave
I'm sorry if this seems OT but I hope someone can still help.
Anyone know how to convert EIAJ into RMS values?
Say if you have an amplifier stating as having 230W EIAJ power, any idea
what that might be in RMS?
I've tried Googling but nothing of sense comes up.
Cheers in advance.
Wavey Dave
Clive George
news:n_idnSQ_V5Bh_iPU...@bt.com...
> Hi all.
> I'm sorry if this seems OT but I hope someone can still help.
> Anyone know how to convert EIAJ into RMS values?
> Say if you have an amplifier stating as having 230W EIAJ power, any idea
> what that might be in RMS?
> I've tried Googling but nothing of sense comes up.
If it's a number on an amp, won't it be about 2W RMS? :-)
Bob Mannix
It depends on the voltage range, I guess, as it's defined as follows:
Maximum EIAJ standard test output power: average of RMS output voltage
squared divided by load impedance.
Don't know what the test conditions are for this though. Probably safe to
say roughly the same as RMS power depending on how you drive it.
--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)
Dave
"Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote in message
news:7Z-dnbyD19Nb-SPU...@posted.plusnet...
No, the power refers to a home cinema surround sound amplifier. I would
think 230W per channel (7.1 surround) is rather high for the home if it
equals 230W RMS output ....... that's twice the power of one of my Marshall
amps !!!! Conversely, 2W RMS is extremely low for an amplifier needed to
power either 20W or 50W speakers.
Dave
Clive George
It was just a little joke based on the way amp manufaturers often choose the
power rating which gives the biggest number, often several times what the
RMS is :-)
Dave
>>>
>>> If it's a number on an amp, won't it be about 2W RMS? :-)
>>>
>>
>> No, the power refers to a home cinema surround sound amplifier. I would
>> think 230W per channel (7.1 surround) is rather high for the home if it
>> equals 230W RMS output ....... that's twice the power of one of my
>> Marshall amps !!!! Conversely, 2W RMS is extremely low for an amplifier
>> needed to power either 20W or 50W speakers.
>
> It was just a little joke based on the way amp manufaturers often choose
> the power rating which gives the biggest number, often several times what
> the RMS is :-)
>
Oh, okay, sorry for that. I know what you mean though, as the current trend
is to advertise amps rated in PMPO (Peak Music Power Output) to make sound
systems seem far more powerful than they really are.
Dave
Dave Plowman (News)
Have you tried to find a handbook or manual on line? This would likely
give the RMS power too.
--
*I don't suffer from insanity, I enjoy every minute of it *
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Dave Plowman (News)
Dave <merlin...@yahoo.co.uk> wrote:
> No, the power refers to a home cinema surround sound amplifier. I would
> think 230W per channel (7.1 surround) is rather high for the home if it
> equals 230W RMS output ....... that's twice the power of one of my
> Marshall amps !!!! Conversely, 2W RMS is extremely low for an amplifier
> needed to power either 20W or 50W speakers.
It's most unlikely all the amps are of the same power. Could be too that
the 230 watts is the total of all the amps.
What's the power consumption of the device? Should be on the back
somewhere.
--
*I see you've set aside this special time to humiliate yourself in public
Dave Liquorice
> ... the current trend is to advertise amps rated in PMPO (Peak Music
> Power Output) to make sound systems seem far more powerful than they
> really are.
Current trend? They have been doing that for 30 years +
As for 230W for a 7.1 sourround system I'd be suspicious about that being
230W total peak for all 8 speakers. ie about 25W peak per channel. IMHO a
decent system would have 230W RMS for each for the front 3 and the sub,
maybe a bit less for the two surrounds.
WTF is 7.1 anyway the majority of stuff is only made in 5.1; Left, Center,
Right, Left Surround, Right Surround and the 0.1 Sub Woofer.
--
Cheers
Dave.
Arfa Daily
"Bob Mannix" <b1o...@mannix.org.uk> wrote in message
news:gplp1n$c57$1...@south.jnrs.ja.net...
sense to the person at the time, but dear me, average of RMS ? Squared ?
Divided by load impedance ? Should it also have "multiplied by the outside
air temperature and divided by the number of channels cubed, minus the
number you first thought of" in there as well ... ?
And as far as the comment that it amounts to about 2 watts RMS per channel,
that's probably not far short of the truth. I have seen many 'home cinema'
systems cross my bench for repair, that have made similar extravagant claims
for their output power, and when you get inside them, there are a couple of
car radio output ICs, mounted on a bit of bent aluminium, and good for 5
watts RMS at best, with a following wind ...
As Dave P. said, if you look at the power input rating plate on the back,
take off 10% for running the deck and so on, and then take 40% of what's
left, that should get you at least on the same planet, in terms of how much
of the input power, is actually being converted to output power. The figure
will of course represent *total* output power, so you will then have to make
estimates of the ratios of front to surround to sub powers. If the unit uses
so called 'digital' output stages (and no, I'm not going to get involved in
a drawn-out discussion of the validity of that term) you could perhaps take
60% of the figure after taking off the 10% background power.
And don't be *too* dismissive of low output powers. Sometimes, a low power
can be surprisingly effective, if it's driven into a decent speaker. For
many years, I ran a Teleton amplifier, purchased from Laskey's or some such
on the Tottenham Court Road - or maybe it was Lisle St - and that was rated
at just 8 watts RMS per channel. I drove it into a pair of decent sized
home-built speakers, and the bass could rattle the windows, and it was
deafening to listen to at around half volume.
Arfa
Bob Eager
But does the volume control go up to 11? :-)
--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com
dennis@home
"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.net...
> WTF is 7.1 anyway the majority of stuff is only made in 5.1; Left, Center,
> Right, Left Surround, Right Surround and the 0.1 Sub Woofer.
Its 5.1 with two side channels added.
It does make effects better IME.
Not that I have anything but the demo that came with my soundblaster that is
7.1.
Dave
>
> Current trend? They have been doing that for 30 years +
Okay, okay .... it should have read "continuing trend" ... ok?
> WTF is 7.1 anyway the majority of stuff is only made in 5.1; Left, Center,
> Right, Left Surround, Right Surround and the 0.1 Sub Woofer.
>
These should explain the 7.1 ch
http://en.wikipedia.org/wiki/7.1ch
http://shop.ebay.co.uk/?_from=R40&_trksid=m38&_nkw=7.1+surround+sound&_sacat=See-All-Categories
And only as an example of the amplifier I was talking about, except that the
one shown is actually 130W per channel:
http://cgi.ebay.co.uk/ONKYO-TXSR506-7-1-AMPLIFIER-HOME-CINEMA-SURROUND-SOUND_W0QQitemZ270347026212QQcmdZViewItemQQptZUK_AudioTVElectronics_HomeAudioHiFi_Amplifiers?hash=item270347026212&_trksid=p3286.c0.m14&_trkparms=72%3A1300%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
Hope that the above will be of help.
Wavey Dave
mick
Googling works...
According to this link it's meaningless if you want to listen to music.
EIAJ is a measurement of maximum square wave power and gives a vastly
inflated rating over any sine wave measurement.
http://hephaestusaudio.com/delphi/2009/02/01/amplifier-power-ratings/
And here:
http://www.d-amp.com/sales.htm
It appears to be average RMS output squared divided by load impedance. An
interesting way to arrive at a comparison figure!
And here:
http://www.billfitzmaurice.net/phpBB3/viewtopic.php?f=6&t=7492
Various means of rating performance have been established, some are much
more strenuous and arguably more realistic than the EIAJ which tests an
amp by feeding it a 1khz tone and increasing power until it reaches 1%
distortion. This gives an exaggerated high power rating, and ( unless you
listen to distorted 1khz tone ) not a typical use of an amp. In general a
EIAJ figure will be at least 20% over a more conservative and realistic
measurement ( full bandwidth 20 - 20Khz .1% or less distortion both
channels driven ).
--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.
Dave
>> >
>> > No, the power refers to a home cinema surround sound amplifier. I
>> > would
>> > think 230W per channel (7.1 surround) is rather high for the home if it
>> > equals 230W RMS output ....... that's twice the power of one of my
>> > Marshall amps !!!! Conversely, 2W RMS is extremely low for an
>> > amplifier
>> > needed to power either 20W or 50W speakers.
>>
>> It was just a little joke based on the way amp manufaturers often choose
>> the
>> power rating which gives the biggest number, often several times what the
>> RMS is :-)
>
> But does the volume control go up to 11? :-)
>
Only on the Marshall's !!!!!!!!!!!!!!
Dave
gazz
"mick" <not....@invalid.invalid> wrote
<snip>
> which tests an
> amp by feeding it a 1khz tone and increasing power until it reaches 1%
> distortion. This gives an exaggerated high power rating, and ( unless you
> listen to distorted 1khz tone ) not a typical use of an amp.
oh i dunno, some of the crap i hear coming from the boy racers cars sounds
not unlike a distorted 1khz tone, just it's usually pulsed on and off
repeatedly for a few hours and sold to them as the latest drum and bass cd.
The Natural Philosopher
>.
>
> And don't be *too* dismissive of low output powers. Sometimes, a low power
> can be surprisingly effective, if it's driven into a decent speaker. For
> many years, I ran a Teleton amplifier, purchased from Laskey's or some such
> on the Tottenham Court Road - or maybe it was Lisle St - and that was rated
> at just 8 watts RMS per channel. I drove it into a pair of decent sized
> home-built speakers, and the bass could rattle the windows, and it was
> deafening to listen to at around half volume.
>
100W into 78db/watt speaker = 1w into 98db/watt speaker
Which is about the range from the worst to the best sensitiviy speakers
I used to deal with..
> Arfa
>
>
The Natural Philosopher
Many valve amps culdnt do 0.1%...art all..anywhere..
And as far as 'not a typical use of an amp' most users cant tell
clipping until it gets to about 30% ....;-)
Sort of average disco type levels. clipping makes it sound 'loud'
I've sat in the middle of four top quality speakers,(about 1Kw total
driven power) peaking around 117dB SPL, and it didn't sound loud, or
painful. Sound bloody brilliant actually..Think I tried dire straits and
bass culture..the latter of course shook the bloody rig about a lot..
meow...@care2.com
P=V^2/R, so the basic idea of EIAJ makes sense. I suspected a square
wave might come into it to massage the figures though.
I dont know which of your quotes is correct:
- if its measured at 1% distortion then it will equal the amp's RMS
output power
- if a square wave is used, the EIAJ power would be apx 2x rms power
with a sine wave.
NT
Bob Mannix
news:EWwvl.34022$Qg1....@newsfe25.ams2...
Well, why I'm not sure, but calculating power as voltage squared over
impedance is perfectly reasonable and no cause to bring in the air
temperature! It's some sort of average that takes into account the dynamic
voltage range of the system. Not that I care, but someone might.
As to the loudness of speakers, efficient speakers are loud and low quality,
high quality speakers are inefficient and quieter (generally speaking) so
you make your choice. Notting Hill Carnival sound system, go for efficiency
and b*gg*r the fidelity, you want to rattle windows, Self absorbed, anally
retentive, solo, esoteric hi-fi listening, low efficiency speakers and big
amps ;o) !
Dave Plowman (News)
Bob Mannix <b1o...@mannix.org.uk> wrote:
> As to the loudness of speakers, efficient speakers are loud and low
> quality, high quality speakers are inefficient and quieter (generally
> speaking) so you make your choice.
Indeed. Recently re-heard some Lowther super efficient speakers mounted in
horn loaded cabinets. Driven off tiny amps. And they sounded horrid -
extremely coloured sound. Might be worthwhile where power was a problem,
though.
--
*Sticks and stones may break my bones but whips and chains excite me*
The Natural Philosopher
> subnormal.
>
No, the amps *were not clipping*. I put a scope on them. Its the HF
stuff that wrecks you.
> I listed to many high power rigs and as a hobby, used to go to air
> shows (60's70's when the EE lightnings etc flew) I always found it sad
> the way some blokes tried to be macho and not cover their ears. Soooo
> funny - until they couldn't hear properly every again.
>
I have never hard a PA rig except one concert with curved air, once,
that was not bing pushed into clipping.
Apart from solo artists and folk stuff. Most sound engineers are a bunch
of cloth eared twats.
> ps I *do* like loud music, Just take precautions - you know it makes
> sense.
The Natural Philosopher
Not necssarily.
> high quality speakers are inefficient and quieter (generally speaking) so
> you make your choice. Notting Hill Carnival sound system, go for efficiency
> and b*gg*r the fidelity, you want to rattle windows, Self absorbed, anally
> retentive, solo, esoteric hi-fi listening, low efficiency speakers and big
> amps ;o) !
>
>
Best speakers we used in my time making rigs, were JBL horn copies by
DAS About 110dB/watt.
Those and bullet horn tweeters covered about 800Hz upwards very very
well. superb low distortion a but the frequency response had a few
little peaks in it.
IIRC we used 8 or 12 inch units at around 92-95dB/watt - massive magnets
on em.
And twin 15" or a single 18" unit to go up to 200hz or so in reflex
cabs. Us of lighweigght foam composite cones and BIG magnets gets a very
decent efficiency out of even those.
What you are thinking of is crappo hifi. Its easy enough to take a
poorly damped speaker and strangle it to get a flattish reponse, and
people want '100W speakers' not 'speakers capable of doing 120db SPL'.
It sounds ok, its just chap. My DAS studio monitors were massively more
efficient. Sadly they have decoiled and need a recone..after 25 yars..
Or if its loud you want, cheap magnet, ultra thin paper cone, a
celestion! and into a box..and hey folks, its the Vox AC30!! a very good
soundboard for an electric guitar, with multiple interesting resonances
and fed from a ovrdriven 100 ohm impedance valve amp with all negative
feedback removed for gain!. You cant get better than that ;-)
Loud, for 30watts..
Dave Plowman (News)
The Natural Philosopher <a@b.c> wrote:
> I have never hard a PA rig except one concert with curved air, once,
> that was not bing pushed into clipping.
You need to go to some proper ones.
> Apart from solo artists and folk stuff. Most sound engineers are a bunch
> of cloth eared twats.
Thanks. And I'm speaking for the other Dave too. ;-)
More likely no sound engineer involved. Just some roadie. We are too
expensive.
--
*I took an IQ test and the results were negative.
Dave Plowman (News)
The Natural Philosopher <a@b.c> wrote:
> well. superb low distortion a but the frequency response had a few
> little peaks in it.
As do all horns. That's why they're useless for true Hi-Fi.
--
*I used to have an open mind but my brains kept falling out *
The Natural Philosopher
> In article <123729893...@proxy02.news.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>> I have never hard a PA rig except one concert with curved air, once,
>> that was not bing pushed into clipping.
>
> You need to go to some proper ones.
>
>> Apart from solo artists and folk stuff. Most sound engineers are a bunch
>> of cloth eared twats.
>
> Thanks. And I'm speaking for the other Dave too. ;-)
>
> More likely no sound engineer involved. Just some roadie. We are too
> expensive.
>
But I have seen engineers in the studio gaily putting clipped percussion
on a track... 'needles not in the red, mate'
The Natural Philosopher
> In article <123730019...@proxy01.news.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>> Those and bullet horn tweeters covered about 800Hz upwards very very
>> well. superb low distortion a but the frequency response had a few
>> little peaks in it.
>
> As do all horns. That's why they're useless for true Hi-Fi.
>
Well, its a tradeoff. Between sensitivity and flat response. And wide
bandwith..
Remember we were only spanning IIRC about two octaves with each unit.
Tweeters came in around 4k, mid horns 1k-4k, lower mid 250hz-1k Bass
units 50-250hz More or less.
I don't think I have ever hard better high power clarity than from those
horns. Quad ESL'S. yes, but at abysmal power output.
You have to pay real money though. The knock off plastic copies are rubbish.
And decide whether its low intermidulation you want, or a razor flat
frequency response. Since any room you put stuff in and any hall you
recrd in buggers up the frequency response I don't count it as a huge
problem. But rooms don't distort ..loudspeakers do. It jut makes the
recording dull.
OK if there is a major and high peak or notch, you can hear it, but not
a minor rippling across the band.
Iv always liked top quality horns, but I have never hard them much
outsid what we were doing..not in the hifi stores anyway.
Arfa Daily
>> I listed to many high power rigs and as a hobby, used to go to air
>> shows (60's70's when the EE lightnings etc flew) I always found it sad
>> the way some blokes tried to be macho and not cover their ears. Soooo
>> funny - until they couldn't hear properly every again.
>>
>
> I have never hard a PA rig except one concert with curved air, once, that
> was not bing pushed into clipping.
Curved Air ! Boy, that takes me back. Back Street Luv was one of my
favourite singles of the 70s ...
Arfa
Dave Plowman (News)
Not uncommon to use controlled distortion for an effect. Or are you saying
only you could hear the clipping?
BTW - if it had a red section it was a VU meter and doesn't read peaks. So
your 'engineer' was pulling your plonker.
--
*The more I learn about women, the more I love my car
The Natural Philosopher
> In article <123730751...@proxy01.news.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>>> More likely no sound engineer involved. Just some roadie. We are too
>>> expensive.
>>>
>> thats entirely possible ;-)
>
>> But I have seen engineers in the studio gaily putting clipped percussion
>> on a track... 'needles not in the red, mate'
>
> Not uncommon to use controlled distortion for an effect. Or are you saying
> only you could hear the clipping?
>
> BTW - if it had a red section it was a VU meter and doesn't read peaks. So
> your 'engineer' was pulling your plonker.
>
No, he simply thought if it was in the green, it was OK!!!
Dave Plowman (News)
The Natural Philosopher <a@b.c> wrote:
> > Not uncommon to use controlled distortion for an effect. Or are you
> > saying only you could hear the clipping?
> >
> I am saying the engineer didn't even bother to listen..
Not a sound engineer, then.
> > BTW - if it had a red section it was a VU meter and doesn't read
> > peaks. So your 'engineer' was pulling your plonker.
> >
> No, he simply thought if it was in the green, it was OK!!!
No green section on any VU I've seen. Must have been domestic gear which
explains a lot.
--
*Generally speaking, you aren't learning much if your lips are moving.*
The Natural Philosopher
> In article <123736349...@proxy00.news.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>>> Not uncommon to use controlled distortion for an effect. Or are you
>>> saying only you could hear the clipping?
>>>
>> I am saying the engineer didn't even bother to listen..
>
> Not a sound engineer, then.
>
>>> BTW - if it had a red section it was a VU meter and doesn't read
>>> peaks. So your 'engineer' was pulling your plonker.
>>>
>> No, he simply thought if it was in the green, it was OK!!!
>
> No green section on any VU I've seen. Must have been domestic gear which
> explains a lot.
>