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. Cheers in advance. Wavey Dave
If it's a number on an amp, won't it be about 2W RMS? :-)
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.
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
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
Have you tried to find a handbook or manual on line? This would likely give the RMS power too.
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.
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.
Who on earth comes up with this stuff ? I'm sure it must have made some 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
But does the volume control go up to 11? :-)
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.
Okay, okay .... it should have read "continuing trend" ... ok?
These should explain the 7.1 ch
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.
And here:
Only on the Marshall's !!!!!!!!!!!!!! Dave
"mick" wrote
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.
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..
ER.. 1% distortion was the norm, not 0.1%, and generally measured at 1Khz.
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..
Then either your figures are junk or your hearing is damaged or subnormal.
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.
ps I *do* like loud music, Just take precautions - you know it makes sense.
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
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