Inflated PMPO figures

Oct 10, 2008 22 Replies

How do some manufacturers of audio amps arrive at the ridiculously high PMPO ratings they give for their products? E.g., an amp with a true 20-watt output may be rated at more than



1000 watts PMPO. (Please, let's not get sidetracked into how there's no such thing as RMS power - call it continuous power or whatever).

I'm old enough to remember when IHF music power was often cited with some justification. At least you could actually get that amount of power output for a fleeting moment at very high THD levels. But multiple-kW ratings are now claimed for a music system using a few TDA2030 ICs. Even large reputable companies do it, so I find it hard to believe that they just grab some random figures out of thin air. Do they have some way of working out those figures, no matter how specious their reasoning might be? I was out of touch with the audio field for a long time, so I guess I missed something when the trend started.


Number out of a hat, praying to donald duck, throwing a dice....

Oh..

The dat sheet says 14W, which is average contineous power. I diont see that it can give out more than around 25w contineous due to its 3.5A current limit.

I dont. They did that with the space shuttle. Like 1:50, so try 1:200, too low, try 1:1000, to low, tray 1:100,000 ok, we can go with that...

Yeah, mulitply by the number of fairies that they thought someone may have seen, last Tuesday.

Kevin Aylward

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They don't. It's exclusive to the car audio market and maybe also computer type audio.

Long ago the FTC (in the USA) introduced a rule that prevented hi-fi manufacturers from doing any such thing.

In Europe, IEC ratings are used.

Graham

p.s. it's called 'the Amplifier Rule'.

Graham

"In the USA" ??? Is there an FTC where you live?

I always thought it was called "Ohms Law". *shrug*

John, what's up with you ? The OP didn't indicate where he lives so 'in the USA' was merely clarification. He may never have heard of them. There is a whole world outside your borders you know.

I don't understand what you mean.

They are somewhat different actually because they're International, not single nation. In fact UL is now patterning after IEC. See UL1950 and IEC950 (may be 60950 by now) for example.

You mean me personally ? I think it has some very good bits and some very bad bits and the bad bits seem to be getting worse at a rate of knots now.

I would gladly now consider re-joining EFTA (see wiki) which would give all the trade benefits without all the compulsory social and generally insane s*it. Did you know the majority of British Law (I think maybe as much as

60%) is now made in Brussels ? The Commission produces 'Directives', which in the UK are executed as 'Orders in Coucil' which may not be debated in Parliament.

If only they'd called the Euro 'The Pound' it expect it would have happened. But that was disallowed. No existing currency name was allowed.

Also remember The Pound was a highly rated currency in its own right, as opposed to say the Italian Lira.

It was like the same silly idea about a 'genuine' Euro power socket. The most popular, the Schuko type and the most safe, The British '13 Amp' are both ruled out. So it'll probably never happen.

Graham

OK. So they do grab those figures out of thin air. I was wondering if there was some way of producing those figures, no matter how false and contrived the math might be.

As an example, the amplified speakers I'm using for my computer is a Kobian SW-1480 (reasonable sound for a USD20 equivalent price tag). It's a 2.1 set using a TDA2030 for each of the woofer and two satellites (4 ohms each), running from a common power supply which is very close to the TDA2030's max rating of +/-18V at idle. Even if the full 36V is squared and divided by 4ohms (an absurd and totally irrelevant 'formula'), the total for all three amps still falls short of 1000W. Yet the PMPO is claimed to be, as the model number suggests, 1480W!! What really surprises me is that similarly absurd figures are touted even by giant multinational companies.

For some bizarre reason the US FTC considered this market under 'the Amplifier Rule' and exempted it !

You'll probably find some obscure reasoning on their site.

Graham

They run it through the same model that the Warmingists use to get their figures. ;-)

Cheers! Rich

Nice retort. Nice, indeed! Your commentary has recently become much more incisive. Has your life changed in any way you\'d like to share? JF

LOL ! There is actually a 'sort of' defintion of pimpo but you don't want to hear it because it's stupid. It can be varied to suit the marketing guys too of course.

Graham

Late at night, by candle light, "pimpom" penned this immortal opus:

At the local computer store I recently walked by a couple of shoe-box sized speakers claming 25,000 W. Got some funny looks as I couldn't resist laughing out rather loudly (much less than 25 kW, though).

- YD.

Remove HAT if replying by mail.

Thanks! :-)

Not especially - Maybe I've abandoned all hope lately, given the two candidates we have for "president".

It used to be "would you rather be hung or shot?" Nowadays it's "Would you rather be disemboweled or boiled in oil?"

Thanks, Rich

Look on the bright side. Some countries allow a third term for president.

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Can you imagine a third term for you know who...?

heh

Michael

I can kinda-sorta understand how Bush weaseled his way in the first time, even though he didn't actually get a majority vote. But who on earth voted for him a second time around?

Hard to understand you Yanks!

Dave.

Nah, Fords are great! Just keep oil in them, and they'll run forever. They are kind of notorious for using oil, however ("Uh, fill up the oil and check the gas...").

Cheers! Rich

Heh. ;-) Actually, I knew that, I just wanted to go for the colloquial form of the expression, more amenable to Joe Six-pack. ;-)

Cheers! Rich

I think you're confusing them with Toyota ! ;~)

Oh, except Toyotas don't use oil.

Graham

Well, they can, especially if:

  1. The Valve Cover is not on tight enough. (I took a 30mm socket and tightened 'em myself, to stop an oil seep.)
  2. The Distributor O-ring leaks. ('92 to '96 Camry)
  3. Worn piston rings or valves

Don't forget the oil gelling (sludge) issues for '97-'01 Camry, and Lexus... Google "toyota sludge", 175,000 hits

Michael

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