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Old 3rd March 2004, 09:32 AM   #31
sreten is offline sreten  United Kingdom
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Take a 10W+10W RMS into 8 ohm amplifier.

So its a 20W amplifier.

And 40W into 4 ohms.

Double this for music power = 80W.

Double this for PMPO = 160W.

Generally PMPO = 8 times the RMS rating.

But you have to be careful, sometimes its x 4, others x 16,
and occasionally devoid of any rational derivation.

sreten.
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Old 3rd March 2004, 09:36 AM   #32
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how do they arrive at this. there must be a formula or some assumptions.
Yes they have a look at the figures of their competitors first and then they decide !

PMPO = Product Managers Power Output !!

Regards

Charles
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Old 3rd March 2004, 10:01 PM   #33
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I would agree with phase on this, the PMPO doesnt seem to bare any resemblance to a RMS figure, at least not from one company to another.

Also take into consideration measured THD. I once saw an advertisement for a sharp mini. power output (small print bottom of ad) 10 watts RMS 10% thd. This obviously means they were quoting output whilst clipping was happening as no amp produces 10% if its not clipping. Well you could design a crap amp that would, but most of these minis use chip amps and a designer wont exactly make the chip a bad design.

Either way power outputs are completly ambiguous outside the audiophile world, everyone wanting to make their numbers BIGGER then everyone elses.

Im sure I have seem some 2watt RMS comp speakers rated at something like 1000watt PMPO, now that is BS. Well maybe an exaggeration but here is a pair in the CPC catalog 22W RMS, 2500 PMPO. Thats 113 times larger
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Old 3rd March 2004, 10:22 PM   #34
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Default PC speakers

Hi,

My PC speakers are 240W pmpo, but weighs about 500grams

There is a big thing in Denmark with PC speaker being rated at up to 350W for a box with a driver that has a max desplacement of less than 2 mm....???

I dont get it, is it not just a case of "mine is bigger than yours"??

\Jens
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Old 3rd March 2004, 10:24 PM   #35
Kengro is offline Kengro  Norway
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Angry Some newer learn

I think watt is the worst illness in audio. Watt is still volt x ampere, And it should be mesured in real playing. 8 ohm 20-20000 hz. But try telling sony and other japanese mass marked manufactures. I've got 2 x 80 but are building a new on 2 x 400. No near houses around me. So louder than hell will be my new thing for a while
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Old 3rd March 2004, 10:50 PM   #36
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Default Agreed with a question

Here, I agree a 'bigger is better' attitude is present. I also think that efficiency is becoming more apparent than in the past decade.

On my bedroom system, with 85-ish dB speakers and a mid-90's HK home theater receiver, if I turn it down so low as to just barely hear it, I only hear the "mid" portion. A few clicks up and I hear most of the range. Many more clicks and they start to "sing." A few more and its just too loud.

Now the question: Is this a function of the speaker design (I doubt it) the amp in the receiver (still kind of doubt it) or a function of my ears? I'm guessing the last one.

Are human ears most sensitive to the ‘mids,’ the region where I guess voices are usually? I have noticed in my car that running speakers from the head unit, a similar phenomenon occurs. When running them from an external amp (no sub) it seems less. I have no idea of the actual dB we're talking, but I'd guess all are well below 75.

Any thoughts on this and (getting back to the topic) how this is related to "big" amps.

All the above being said, I find the low powered GC I have (very inadequate heatsink) even satisfying on the 85dB speakers. 100 commercial Watts just isn't what its cracked up to be.

Sandy.
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Old 3rd March 2004, 10:56 PM   #37
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Are human ears most sensitive to the ‘mids,’ the region where I guess voices are usually?
yes

Click the image to open in full size.

the lowest curve, "Hörschwelle" is the sensitivity
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Old 3rd March 2004, 11:05 PM   #38
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That "most sensitive" range there ~3-4Khz...that's crying baby/screaming woman isn't it?
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Old 4th March 2004, 12:21 AM   #39
sreten is offline sreten  United Kingdom
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treat the scale on the left as your volume knob,
and all should become apparent,

sreten.
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Old 4th March 2004, 03:23 AM   #40
dooper is offline dooper  Canada
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Ah yes, Fletcher and Munson. Useful reminder - thanks sreten.

dooper
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