Essence Audio - High Fidelity Help & Hints - Article
Peak Music Power Output (PMPO)
Is Peak Music Power a genuine indication of power output ?
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In a word, NO!
Peak Music Power is nothing more than a clever and somewhat deceptive marketing tool.
The reason for this answer lies in the quite deliberate method used by some manufacturers to measure an amplifier's power output.
Peak Music Power Output (sometimes also known as Peak Momentary Power Output) is calculated under perfect conditions and at 100% efficiency (hardly a realistic scenario). In fact, some manufacturers actually connect their products up to enormous power supplies and read the power output at the point of destruction!
Audio amplifiers may be able to deliver enormous amounts of power for a fraction of a second. However this is clearly NOT sustainable in the real world, unless you are keen on the idea of watching smoke rise from the back of your Hi-Fi gear (something I have actually witnessed on more than one occasion!)
Restrictive circuitry losses can produce considerable heat in the various audio amplifier stages. As a result, if power levels are maintained above a critical point, the resulting stress will eventually cause either component damage or even complete failure of one or more amplifier stages. In a best case scenario (read: if you were lucky), the power supply might fail first, sparing the amplifier stages.
We have all seen the computer vendors advertising “600 Watt Multimedia Speakers” with their budget systems. A most deceptive description for sure, but one that probably sounds great to the novice buyer ... and one that has no doubt led to a good many sales of greatly overated products.
The true measure of Audio Output Power is R.M.S. (Root Mean Squared) also known as Continuous Power.
The important part here is the use of the word "Continuous".
The RMS rating, measured in Watts (voltage x current), for an amplifier is the highest amount of power that an amplifier can deliver continuously ... without failing!
In other words, the RMS specification is a true indication of the actual real-world power output limits of a given amplification device.
The higher the RMS figure, the louder and cleaner your music will sound.
So when selecting an amplifier, don’t be fooled by impressive sounding (but hugely inflated) power output figures. Ask your vendor for specifications on the particular audio device you are interested in. And in particular, look for the R.M.S. power output figures. If these are not included ... walk away!
The rated output in Watts RMS, will give you a true and definitive indication of an amplifier's performance.
Essence Audio - Music First!
June 2008 - Updated May 2010