PMPO = Peak Music Power Output/Peak momentary power output

[ElectroEnthusiast]

I have a bit difficulty in understanding PMPO - the two different definitions about it and its purpose, and a question: Is it anything related to power consumption of the audio appliance?
Anywhere i can understand it clearly, pls elaborate your explanation.
PMPO = Peak Music Power Output/Peak momentary power output??

 

[alexan_e]

The only purpose behind them is marketing, these aren't defined like RMS watts so it is a good way to fool potential customers by using big stickers that advertise 200W or 250W PMPO.
These peak measurements have no specification for the distortion or the duration and are useless.

Check the wikipedia explanation Audio power - Wikipedia, the free encyclopedia
"Peak Music Power Output (PMPO), sometimes misused in advertising as Peak momentary performance output, is a much more dubious figure of merit, of interest more to advertising copy-writers than to consumers. The term PMPO has never been defined in any standard, but it is often taken to be the sum of some sort of peak power for each amplifier in a system. Different manufacturers use different definitions, so that the ratio of PMPO to continuous power output varies widely; it is not possible to convert from one to the other. Most amplifiers can sustain their PMPO for only a very short time; loudspeakers are not designed to withstand their stated PMPO for anything but a momentary peak without serious damage.

Peak momentary power output and peak music power output are two different measurements with different specifications and should not be used interchangeably. Manufacturers who use different words such as pulse or performance may be reflecting their own non-standard system of measurement, with an unknown meaning. The Federal Trade Commission is putting an end to this with Federal Trade Commission (FTC) Rule 46 CFR 432 (1974), affecting Power Output Claims for Amplifiers Utilized in Home Entertainment Products.

Remembering that neither specification is universally standardized and different companies use different definitions, the typically understood differences between Peak Momentary and Peak Music Power Output are as follows. Peak Momentary Power Output is measured by the components ability to pass a single peak or a short train of peaks, usually fewer than ten contiguous wave cycles, without distortion or loss in power output. Peak Music Power Output, in contrast, is measured by the components' ability to pass at least ten contiguous wave cycles without distortion or loss in power output.

It is generally agreed that PMPO numbers do not have any correlation to system performance, and they are probably made up in most cases."

Alex

 

[ElectroEnthusiast]

The only purpose behind them is marketing, these aren't defined like RMS watts so it is a good way to fool potential customers by using big stickers that advertise 200W or 250W PMPO.
These peak measurements have no specification for the distortion or the duration and are useless.

Alex

Purpose is for marketing: What makes them fool? Is it 'Bigger the number' make them feel the system is good? How is related to power of the system?

 

[RCinFLA]

Every wonder how as set of amplifed speakers have a 50 watt advertised power output with a 12v 0.5 amp wall wart power source.

 

[ElectroEnthusiast]

Every wonder how as set of amplifed speakers have a 50 watt advertised power output with a 12v 0.5 amp wall wart power source.

Thats right, but speakers aren't lited using a wall wart.
You mean to say 'PMPO is no way related to Power of the device'?

 

[alexan_e]

PMPO have no relation to the real capability of the device (speaker or amplifier), they can't be compared between devices (even of the same kind).
The PMPO is supposed to be an output power surge that the device can handle but there is absolutely no standard for the duration or the distortion levels and sometimes the number is not even based on measurements.
On the other hand PMPO is a clear indication that the manufacturer wants to impress with the high power rating of the device, if the RMS rating is not provided in the manual or a datasheet then you will not be able to find the true potential of the device unless you measure it yourself.

Alex

 

[ElectroEnthusiast]

Here's some information:

Have you ever wondered how that little set of powered speakers on sale at the store could contain a 120 watt or otherwise large amplifier? Likely, these large numbers are describing PMPO or "music power" figures rather than sustainable wattage.

PMPO, Peak Music Power Output, music power, or peak power describe the ability of an audio amplifier to provide very short but large bursts of power. As music is typically quite dynamic with alternating loud and soft portions, an amplifier can be built to provide very high power to the loud bursts while falling back to safe levels for most of the song. PMPO is the amount of power which is momentarily provided to these loud bursts in music.

Marketing departments at electronics companies like PMPO because it allows them to build a cheap product with minimal power supplies and amplifier components yet still display big numbers on the box. Naive consumers who couldn't care less about sound quality will purchase the product because they think it is cool to have a 3600 watt amp that draws power from an 1800 watt maximum electrical outlet.

Because the power supplies are often undersized as well as the amplifiers' active devices (chips, transistors), there is likely to be extreme distortion produced when the PMPO power is reached, as the power supply voltage will drop and the filter capacitors will be drained in the process of producing large peaks of audio output. Low-impedance speakers such as 3.2 ohms are commonly provided with PMPO-rated devices to push the amplifier as far as possible.
PMPO Standards?

PMPO values seemed to vary between manufacturers and even products themselves, so there appear to be no universal standards used in defining PMPO. Typically, the true sustainable power handling ability of an amplifier is stated in "RMS Watts??", the root mean square power of a constant sine wave (e.g. a 1 kHz tone) signal that can be amplified without overheating the amplifier and/or grossly distorting the signal.

RMS power ratings are more legitimate because they require the amplifier to have an adequate power supply and adequate heat sinking to remove any waste heat that is produced as a resulting of producing the output power. Attention must also be paid to the amount of distortion the amplifier produces when producing a given power output.
An Example...

I have personally seen a stereo system which claimed a 50-watt PMPO power output. I found the unit in a dumpster at a college apartment complex, beat up pretty badly but still retaining the fluorescent yellow marketing stickers with PMPO ratings on the front (never removed by the owner). On the back of the stereo, the power input rating from the AC line is 24 watts.

The transformer core looked to be rated at most 20 volt-amps (~16 watts)

The power supply was 12 volts, single-ended - one "rail" supplying only a positive voltage, indicating that this was probably a "Class B" amplifier which only amplifies half of the audio waveform. High-quality Class A and Class AB amplifiers typically employ both a positive and negative rail. 12 volts also severely limits the amount of power which can be provided to speakers. The low-impedance 3.2-ohm speakers supplied with this unit, however, were not the limiting factor.

There was a 2-ampere fuse in line with this 12 volt power supply, which means a maximum power to the entire stereo (amplifier, tuner, and CD player) or 12 * 2 = 24 watts.

There was 1000 uF of filter capacitance in the power supply. Even for a 2-amp supply this is under-rated, which means there will be ripple (noise) entering the amplifier when it is operated at high volumes.
Power Isn't Everything

The quality of an audio system is not determined by its power output. Large wattage figures in bright bold letters on audio equipment packaging should be an indication that the manufacturer is looking to sell the product based upon quantity rather than quality, and you can expect to get poor quality speakers and amplifiers in such packages.