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27th January 2003, 09:23 #1
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What is the relation of RMS to PMPO rating?
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

27th January 2003, 09:40 #2
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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.
:lol:
~niks~

27th January 2003, 10:15 #3
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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

27th January 2003, 10:32 #4
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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

27th January 2003, 11:05 #5
pmpo rms
Manufacturers uses it because big numbers looks better :)
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 :D

27th January 2003, 11:05

27th January 2003, 11:06 #6
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rms pmpo
NONO
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

27th January 2003, 14:52 #7
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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.

27th January 2003, 14:52

27th January 2003, 15:44 #8
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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

27th January 2003, 15:44

28th January 2003, 05:51 #9
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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) ]

28th January 2003, 06:20 #10
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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.

2nd February 2003, 12:55 #11
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what is pmpo and rms
Hi all,
up to now I saw these PMPOstuff 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

2nd February 2003, 13:17 #12
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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.

2nd February 2003, 19:27 #13
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 outputpower ratings
to find a common reference to the performance of amplifiers. The EIA
MusicPower rating is defined as the power with 5% or less
TotalHarmonicDistortion (THD) after a sudden application of a signal
for a short interval to prevent supply voltages to drop from their
nosignal 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. PowerSupply 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 powerpeak while already delivering some degree of output
power. The times a amplifier is required to deliver a peak that is
preceded by no or lowsignal 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

2nd February 2003, 21:36 #14
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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.

3rd February 2003, 02:32 #15
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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. :?:

3rd February 2003, 02:35 #16
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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.

3rd February 2003, 07:01 #17
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what is pmpo output
Please read the article in the link attached:
http://sound.westhost.com/power.htm
It sums up the subject beautifully.

4th February 2003, 00:05 #18
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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 ;)
Cheers ;)

4th February 2003, 00:05

4th February 2003, 00:53 #19
pmpo to rms conversion
the usual ratio pmpo/rms is 24x.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

4th February 2003, 07:46 #20
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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
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