RMS vs PMPO

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EcraZ

Joined: 17 May 2001
Posts: 325

27 Jan 2003 9:23 pmpo vs rms

The power is actually measured in RMS in audio where as it is customary to indicate the power in PMPO now simply because it shows a high figure (as compared to rms).
Can anybody tell me what is the relation of rms to pmpo rating

thanks

niks

Joined: 18 Mar 2002
Posts: 190
Helped: 2

27 Jan 2003 9:40 rms vs pmpo

An RMS power value is referred to as the real music power output of a speaker. It is a true indication of the output power of a given speaker across it's range of pickup frequencies.

PMPO (Peak Music Power) refers to the maximum amount of power output that the speaker can produce at it's peak. A PMPO rating is not necessarily indicative of the performance of a speaker throughout a wide frequency range.

As a general rule, the higher the true RMS rating of a speaker, the higher it's actual power or volume output.

Laughing

~niks~

EcraZ

Joined: 17 May 2001
Posts: 325

27 Jan 2003 10:15 rms to pmpo

true

what i need to know is given a rating in PMPO how do i calculate the rms power. As rms is the true rating i'd like to convert the pmpo rating into rms to know what is the real power.

thanks

jzaghal

Joined: 31 Jul 2001
Posts: 220

27 Jan 2003 10:32 pmpo to rms

Hi,

Since a long time rms was used,and is the real thing.
Why refer to pmpo, what is it's use ???
( A question I always wanted an answer for it !!)

Thanks

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27 Jan 2003 10:32 Ads

HMX

Joined: 07 May 2001
Posts: 49
Location: Czech rep.

27 Jan 2003 11:05 pmpo rms

Manufacturers uses it because big numbers looks better Smile

as I know the PMPO is calculated by multipying some numbers as total input power, number of screws used and other numbers, nobody knows what their means and multiply by some unknown constant. So, the result is totally unusable number, reporting nothing about real capabilities Very Happy

EcraZ

Joined: 17 May 2001
Posts: 325

27 Jan 2003 11:06 rms pmpo

NO-NO
I don't want to knowq the pmpo rating instead i want to know the rms rating of what is given in pmpo. iam myself verymuch annoyed by the pmpo ratings that have become so prevalent .

regards

bimbla

Joined: 13 Jul 2001
Posts: 541
Helped: 13

27 Jan 2003 14:52 rms to pmpo conversion

I think there is no mathematical formula for conversion of power in rms--->pmpo and vice versa.

Reason:
pmpo is the ability of the amplifier to deliver large amount of power than the rated power BUT only for a fraction of a

time. This will depend on the indivisual amp design and depends largely on the size of the filtre caps.

pmpo is the ability of the loudspeaker to deliver large amount of power than the rated power BUT only for a fraction of a

time. This will depend on the indivisual loudspeaker construction and depends largely on the quality of the magnet and the

peak excursion of the cone.

The best way to check the approximate power level of your system is to measure the o/p section rail voltages to calculate

the power rating of the amp.

This is my own view. So commments are welcome.

bimbla.

2000

Joined: 14 May 2001
Posts: 89

27 Jan 2003 15:44 rms and pmpo

hello pals,

As long as I know, PMPO goes for Peak Maximum Power Output and its relation to the RMS value depends on several factors. As a RMS value depends on the shape of the wave, so it does the PMPO. Due to the complexity of the audio signal and overshoot response of the amplifier, it would be impossible to predict EXACTLY the RMS<->PMPO relation. What in matter exists is some rules of thumb.
I guess it could help a bit,

regards,

2000

EcraZ

Joined: 17 May 2001
Posts: 325

28 Jan 2003 5:51 convert rms to pmpo

to find rms power from Vpp on speakers

P(rms) = (Vpp x Vpp)/8R(load)

to find Vpp from required rms power

Vpp = Sq.root [P(rms) x 8 x R(load) ]

flatulent

Joined: 19 Jul 2002
Posts: 4926
Helped: 328
Location: Middle Earth

28 Jan 2003 6:20 rms pmpo conversion

These higher value measurement types try to provide a more realsitic value when real music is used. Real music has a high peak to average or RMS ratio.

In speakers, a lot of the power is turned into heat in the speaker voice coil. The speaker has a lot of linear range in moving air, but the heat removal capacity of the voice coil is limited. Therefore a peak type short term value is used for its power rating.

In amplifiers, there are two limits. One is the power supply filter capacitors having large ripple under high load current. The other is the heat removal from the transistors. Again, because of the nature of music, the one sine wave cycle maximum power is the rating.

Spasomat

Joined: 19 Jun 2002
Posts: 29

02 Feb 2003 12:55 what is pmpo and rms

Hi all,

up to now I saw these PMPO-stuff only on cheap computer speakers.
You know, these insane rated 200Watts PMPO devices fed by a power supply capable of delivering 10Watts Wink

For a dynamic point of view the crest factor is used, at least at serious amplifier manufacturers.

Have fun,

Spasomat

bimbla

Joined: 13 Jul 2001
Posts: 541
Helped: 13

02 Feb 2003 13:17 pmpo and rms

Let any one not try to calculate PMPO to rms. Since we do not know te criterion used to convert rms to PMPO in the first case.

bimbla.

E-design

Joined: 01 Jun 2002
Posts: 980
Helped: 69

02 Feb 2003 19:27 convert pmpo to rms

This is a typical sales trick. Manufacture's like to confuse the
public with PMPO ( Peak Music Power Output ) ratings as to True RMS
ratings. The Institute of High Fidility (IHF) and the Electronic
Industries Association (EIA) tried to standardize output-power ratings
to find a common reference to the performance of amplifiers. The EIA
Music-Power rating is defined as the power with 5% or less
Total-Harmonic-Distortion (THD) after a sudden application of a signal
for a short interval to prevent supply voltages to drop from their
no-signal values. For a stereo or quad output system the total rating
is the sum of all the channels. The IHF's dynamic output is measured
with a constant supply voltage and allowing less than 1% THD-
distortion.The second IHF method requires a complex input signal (
random ) to look like speech and music. Power-Supply transients,
ripple and other factors are taken into account. This also produces
the lowest and more realistic specifications of the lot.

All of the above methods have a common error, even with the transient
test. No method takes into account the amplifier's capability to
deliver a power-peak while already delivering some degree of output
power. The times a amplifier is required to deliver a peak that is
preceded by no or low-signal conditions are a very few.

Music Power ratings are normally quoted 2 to 3 times higher than the
True RMS ratings. The customer is fooled by the high rating which as a
result produce better sales.

E

flatulent

Joined: 19 Jul 2002
Posts: 4926
Helped: 328
Location: Middle Earth

02 Feb 2003 21:36 rms to pmpo converter

There is a real economic reason for this rating system. Should consumers have to pay several times the price for features they will never use and experience the nuisance of equipment being several times heavier? In this case being able to generate continuous tones at full volume without overheating their equipment while damaging their ears.

This system uses real program material to determine the heat sinking and long term current ratings of components.

jinboqiu

Joined: 25 Nov 2001
Posts: 39
Helped: 2

03 Feb 2003 2:32 rms to pmpo calculator

We can use PMPO to discribe the max output ability of an audio amplifier.But if an audio amplifier work at that point,the THD or SNR often much bad than the rated work condition specificed @ normal RMS power. Question

flatulent

Joined: 19 Jul 2002
Posts: 4926
Helped: 328
Location: Middle Earth

03 Feb 2003 2:35 what is rms and pmpo

The distortion is not increased by using smaller heat sinks or by using a power transformer/output capacitor combination that can supply the peak currents without overheating, but would overheat if these currents were drawn all of the time.

The silicon parts and passive parts are the cheapest part of the product. No scrimping is done on them. It is the cabinet, power supply, and heat sinks that drive the cost and weight.

strabush

Joined: 10 Apr 2002
Posts: 86
Helped: 6

03 Feb 2003 7:01 what is pmpo output

Please read the article in the link attached:
http://sound.westhost.com/power.htm
It sums up the subject beautifully.

turttle

Joined: 31 May 2001
Posts: 45
Helped: 5

04 Feb 2003 0:05 rms & pmpo

Someway already said, but to summarize and as far as I know:

There is no formula to convert PMPO<->RMS, in fact I saw time ago amplifiers from the same manufacturer (I can't remember who it was) with the same RMS and diferent PMPO (or viceversa I only remember they were unpaired).

RMS is a more realistic way to measure power capability but musical experience has a lot of content where PMPO is a useful number, then don't dawn any of them Wink

Cheers

ghettoman

Joined: 02 Apr 2002
Posts: 116
Location: romania

04 Feb 2003 0:53 pmpo to rms conversion

the usual ratio pmpo/rms is 2-4x.if the amplifier is a known brand like sony or pioneer it`s around 2.so if it has 40w pmpo the usualy din value is around 20w DIN or rms.if the amplifier is made on the ship and the name of the amplfier is the captain`s name (like futaky ,matsumio ,domotek ) the ratio can be up to 10 times or more

to be shure just conect an analog voltmeter on a dummy load and read the peak voltage.then use the old p=u x i and voila

EcraZ

Joined: 17 May 2001
Posts: 325

04 Feb 2003 7:46 pmpo rms conversion

I observe that if

The Peak value is considered on speaker/output then,

P(rms) = sq(Vpp)/8R(L) = Sq (Vp)/2R(L)

ie; P(peak) = 2 P(rms)

The Peak to Peak value is considered on speaker/output then,

P(rms) = (1/8 )* sq(Vpp)/R(L) =(1/8 )* P(peak)

ie; P(peak) = 8 P(rms)

your feedback please

regards

R00KIE

Joined: 19 Jan 2003
Posts: 148
Helped: 20
Location: Portugal

11 Feb 2003 15:06 rms=pmpo

it seems to me that all this is to fool the consumer when buying a equipment. and no one decides to do a ommon measure standart because it's not good for profits. but there are companies like technics that supply both RMS and PMPO output capacity of the amplifier.

i would like to say that this is a question I always wanted an answer for.

Manoochehr

Joined: 11 Oct 2001
Posts: 29

16 May 2006 8:15 rms or pmpo

I have an approximate formula based on my experiance on various speaker powers and their PMPOs.

RMS=PMPO/(10*sqrt(2))

So 14W PMPO = 1W RMS

rrahul

Joined: 29 Dec 2006
Posts: 1

29 Dec 2006 20:45 pmpo to rms converter

Am plannin to go in for car audio speakers soon (rear speakers, 6"x9").
I have two options, not sure which one to go in for:

Pioneer: 460w pmpo, 80w rms
JBL: 300w pmpo, 100w rms

Now can anyone help me out with this please?

rkodaira

Joined: 08 Jun 2004
Posts: 332
Helped: 54
Location: Sao Paulo - Brasil

29 Dec 2006 22:52 p.m.p.o vs rms

Huh forget the power numbers. Check if your head unit amplifier channels powers do not exceed the nominal speakers power (the power nominated in "Wrms" (there is no watts rms, the term "rms" only applies to voltage and current, not to power), I would check also the frequency response of the combined speakers (triaxials ? coaxials ?). Both brands are good, maybe the decision could be made upon the prices. You will not put maximum power over them, or will you ?

In fact, cars are not the best place to hear music (but a lot of guys like to blow theirs ears with junk and loud sound).

klumpy

Joined: 07 Oct 2007
Posts: 1

07 Oct 2007 12:19 rms versus pmpo

Another way of looking it is that RMS indicates continuous power and pmpo peak power only. eg if an amp has 100w pmpo and if you use it close to this peak power then the chances are you'll get distortion with a chance of blowing your output load eg yr speakers( see bandwidth). one reason why the cheap hifis are rated in pmpo is that it looks good. RMS on the other hand is average power and gives a better indication of the power capable of being delivered without distortion. I usually consider pmpo as being about 4 times greatr than RMS on any cheap system. rms incidentally is much easier to convert to a logarithmic/decibel rating which leads into the bandwidth capable of being delivered( not applicable to pmpo since this is measured only at one peak frequency usually the low base frequencies, since this gives maximum output power)

featherspeed

Joined: 23 Oct 2007
Posts: 1

23 Oct 2007 19:41 how to calculate pmpo from rms

if i remember corectly your rms value is 0.73 or round about there
and your peak value is at the top of your wave and seing that the peak value is only at its peak for a very short amount of time compared to the rms value weare you have the same value and more for the rest of the wave