Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

What is the relation of RMS to PMPO rating?

Status
Not open for further replies.

EcraZ

Full Member level 4
Joined
May 17, 2001
Messages
201
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Activity points
1,232
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

Full Member level 3
Joined
Mar 18, 2002
Messages
189
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,296
Activity points
1,385
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~
 

EcraZ

Full Member level 4
Joined
May 17, 2001
Messages
201
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Activity points
1,232
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

Full Member level 2
Joined
Jul 31, 2001
Messages
130
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Activity points
955
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
 

HMX

Member level 2
Joined
May 7, 2001
Messages
43
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
Czech rep.
Activity points
273
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
 

EcraZ

Full Member level 4
Joined
May 17, 2001
Messages
201
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Activity points
1,232
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

Advanced Member level 1
Joined
Jul 13, 2001
Messages
419
Helped
23
Reputation
46
Reaction score
8
Trophy points
1,298
Activity points
3,608
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

Member level 5
Joined
May 14, 2001
Messages
87
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
764
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

Full Member level 4
Joined
May 17, 2001
Messages
201
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Activity points
1,232
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

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
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

Junior Member level 3
Joined
Jun 19, 2002
Messages
29
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
208
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

Advanced Member level 1
Joined
Jul 13, 2001
Messages
419
Helped
23
Reputation
46
Reaction score
8
Trophy points
1,298
Activity points
3,608
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

Advanced Member level 5
Joined
Jun 1, 2002
Messages
2,014
Helped
507
Reputation
1,016
Reaction score
407
Trophy points
1,363
Activity points
14,195
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

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
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

Member level 1
Joined
Nov 25, 2001
Messages
39
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,286
Activity points
255
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. :?:
 

flatulent

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
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.
 

turttle

Member level 2
Joined
May 31, 2001
Messages
44
Helped
5
Reputation
10
Reaction score
0
Trophy points
1,286
Activity points
336
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 ;-)
 

ghettoman

Full Member level 1
Joined
Apr 2, 2002
Messages
95
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Location
romania
Activity points
798
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

Full Member level 4
Joined
May 17, 2001
Messages
201
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Activity points
1,232
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
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top