PMPO vs RMS

[EvanTate]

Ok here's the thing. Everyone sees either PMPO or RMS on the audio equipment when they look, but no one really understands the cconnection (if there is actually even a connection).

So, I was going to ask, but decided to use my brains. By brains I mean Google of course...

This is basicaly what I have come up with:

RMS is the true power of your speakers, where as PMPO is the peak power of your speakers.

What's the difference between true power and peak power you may ask? Because we all know that the true power would be the loudest setting possible right? WRONG! Because as is with most things, the speakers cant run at peak power all the time or they will blow.

Another thing is there doesn't seem to be a standard for calculating PMPO between different manufacturers so a Pioneer, JVC and Sony speaker, all 6x9s and all 300w RMS, could all have different PMPO ratings.

This also means that there is no mathematical way of converting RMS into PMPO or vice versa.

The reason PMPO ratings are used is the simple fact that big numbers sell better, especially when you have no clue what they actually mean. For example, you no nothing about systems, ratings, power, watts. You have the typical assumption that more/bigger speakers mean better sound. Now, you're standing there and you see two sets of speakers. One is rated at 200w RMS and the other is rated at 1000w PMPO. You don't know what that means, but you see they're the same price, so naturaly you go for the 1000w.

Same goes for amps.

So do yourselves a favour when your speaker/amp shopping. Look for RMS and not PMPO.

PS: This is very, very, vvveeerrryyy inconclusive so if anyone has anything to add please do so.
PPS: Not sure here, maybe this should be in reference material although it is sound exclusive...

[WezGSI]

[crispy boss]

for amps


add up the fuses x 14.4v

= real constant power

[Nemesis]

2nd time i see you post this crispy and I have to correct you. you right in adding the fuses on the amp and multiplying but rather use 13.8v as 14.4v isn't always achieved even at idle. so your formula now reads for eg. on a 4ch class ab amp
2x30amp fuses x 13.8 = 828 rms (not possible) but lets go further...
take the 828 rms x 0.5 as power is lost due to heat (hence your amp getting warm when playing it) and you end up with 414rms
divide that by the 4 channels and you end up with 103.5rms per channel.
class ab amps arent very efficient due to it losing power through heat, therefore monoblocs (class d amps) tend to run cooler but has a higher distortion level and are therefore mainly used for subs. calculation for a monobloc you would just have to multiply by 0.9 (instead of 0.5) and you wouldnt have to divide by anything as there is only 1 channel.
this is a very useful calculation when shopping for amps especialy when "unbranded" products use PMPO/max power ratings on there amps. please dont change the fuses on your amp to something higher and then do the calculation. you are only going to fool yourself.

enjoy

[crispy boss]

2nd time i see you post this crispy and I have to correct you. you right in adding the fuses on the amp and multiplying but rather use 13.8v as 14.4v isn't always achieved even at idle. so your formula now reads for eg. on a 4ch class ab amp
2x30amp fuses x 13.8 = 828 rms (not possible) but lets go further...
take the 828 rms x 0.5 as power is lost due to heat (hence your amp getting warm when playing it) and you end up with 414rms
divide that by the 4 channels and you end up with 103.5rms per channel.
class ab amps arent very efficient due to it losing power through heat, therefore monoblocs (class d amps) tend to run cooler but has a higher distortion level and are therefore mainly used for subs. calculation for a monobloc you would just have to multiply by 0.9 (instead of 0.5) and you wouldnt have to divide by anything as there is only 1 channel.
this is a very useful calculation when shopping for amps especialy when "unbranded" products use PMPO/max power ratings on there amps. please dont change the fuses on your amp to something higher and then do the calculation. you are only going to fool yourself.

enjoy

thanks nemesis

i figured that heat would affect conduction but never knew it would be that much.

i have to get my system sorted next month

[16Vwiegie]

2nd time i see you post this crispy and I have to correct you. you right in adding the fuses on the amp and multiplying but rather use 13.8v as 14.4v isn't always achieved even at idle. so your formula now reads for eg. on a 4ch class ab amp
2x30amp fuses x 13.8 = 828 rms (not possible) but lets go further...
take the 828 rms x 0.5 as power is lost due to heat (hence your amp getting warm when playing it) and you end up with 414rms
divide that by the 4 channels and you end up with 103.5rms per channel.
class ab amps arent very efficient due to it losing power through heat, therefore monoblocs (class d amps) tend to run cooler but has a higher distortion level and are therefore mainly used for subs. calculation for a monobloc you would just have to multiply by 0.9 (instead of 0.5) and you wouldnt have to divide by anything as there is only 1 channel.
this is a very useful calculation when shopping for amps especialy when "unbranded" products use PMPO/max power ratings on there amps. please dont change the fuses on your amp to something higher and then do the calculation. you are only going to fool yourself.

enjoy

Excellent explanation

[GFunk]

RMS vs PMPO Technically this formula should apply.
RMS = 0.707*Peak ( Not PMPO )
Did you know that the 220V in your house is actually the RMS of the mains voltage.Its Peak goes to 311V.
Peak = RMS/0.707. Thats why its so dangerous to work on TV's The mains capacitor charges t0 311V DC.
Manufacturers is conning us with their PMPO value and you do a RMS calc from there it does not correspond to their RMS value.
Rather go according to RMS value Root Mean Square or the average value.

[Dan]

PMPO means as close to absolutely nothing as makes no difference. Ignore it! It's just marketing BS.

For amplifiers you want to look at output power in watts.

For speakers input power in watts is what you are after.

The 2 should be matched or the amp slightly stronger.

Manufactures usually refer to these ratings as RMS values or nominal ratings.

A "50x4" head unit is usually in the region of 22W RMS output on each of its 4 channels.

The RMS value as mentioned earlier is the peak power divided by the square root of two, but only for a sinusoidal wave, such as AC power transmission. Sound is however not sinusoidal and therefore cannot be calculated in this manner. In this case the RMS value can rather be thought of as an average power value for a sound wave which would be iregular in shape.

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[cyberpuppy]

It's like flywheel horsepower versus wheel horsepower. It doesn't matter if you're making 150kW at the flywheel but you've only got 110kW turning the wheels.

[$haggy]

and then 80kw's worth when you lose traction

[Pantera]

What a manufacturer claims is also useless, if you buy a Chinese cheaper amp, it will not even make what its rating is, that why there is a difference with a good amp, not only sound quality, but you get the actual power you are paying for


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