# The Truth About Amplifier Power Ratings

#### MisterBill2

Joined Jan 23, 2018
6,285
Some amplifier power ratings are quite accurate while many others are quite imaginative, and some are just total lies. That has been my observation since the first time I read an amplifier power rating. It is not likely that anything has changed in the past many years.

#### Audioguru again

Joined Oct 21, 2019
1,570
I say that amplifier and speaker fake power is rated in Whats instead of Watts.

#### DickCappels

Joined Aug 21, 2008
6,451
I have one of those. On the face of it are the words "1200 Watts PMP" Looking inside there were about six TO-92 transistors and not much more. It was worth the US$10 equivalent just for the laugh. #### MisterBill2 Joined Jan 23, 2018 6,285 I have one of those. On the face of it are the words "1200 Watts PMP" Looking inside there were about six TO-92 transistors and not much more. It was worth the US$10 equivalent just for the laugh.
The amazing one that I saw was a set of amplified computer speakers with a claim of 100 watts output, powered by a wall wart specified as "12 volts @100mA. It might have been 100 MILLIWATTS output, a believable number.

#### WBahn

Joined Mar 31, 2012
25,900
I have one of those. On the face of it are the words "1200 Watts PMP" Looking inside there were about six TO-92 transistors and not much more. It was worth the US\$10 equivalent just for the laugh.
Ah, yes, the infamous "peak music power".

That's like all of the air compressors, with a 115 VAC 15 A plug, that are labeled as 5 HP or even higher. I've been waiting for someone to call it "peak air power".

#### MisterBill2

Joined Jan 23, 2018
6,285
Ah, yes, the infamous "peak music power".

That's like all of the air compressors, with a 115 VAC 15 A plug, that are labeled as 5 HP or even higher. I've been waiting for someone to call it "peak air power".
That "PMP" may stand for "Peak Milliwatts Power", which might be close. IHF power was an interesting term, as was IPP.
IHF was the power output if a solid pwer supply were connected in place of the actual power supply, so that the voltage would not vary at all.
IPP power is the power of the first half-cycle of a tone burst, before the supply voltage drops or anything heats up.

RMS watts is an an interesting claim, possibly the product of RMS volts out times RMS amps out, but it is never mentioned in any engineering books of any kind. Probably it relates to steady-state watts at some distortion level.

#### Papabravo

Joined Feb 24, 2006
13,910

#### MrSoftware

Joined Oct 29, 2013
1,803
This guys youtube channel, while very high level, is entertaining. He tests the power output for different audio amplifiers, from way back when they were true class A/B to now when they're almost all class D, from big names and no-names. What you will see is that some ratings are complete lies, and some are significantly under-rated. Any of you guys who were ever into car audio will immediately recognize lots of the names and models.

#### MisterBill2

Joined Jan 23, 2018
6,285

#### WBahn

Joined Mar 31, 2012
25,900
That "PMP" may stand for "Peak Milliwatts Power", which might be close. IHF power was an interesting term, as was IPP.
IHF was the power output if a solid pwer supply were connected in place of the actual power supply, so that the voltage would not vary at all.
IPP power is the power of the first half-cycle of a tone burst, before the supply voltage drops or anything heats up.

RMS watts is an an interesting claim, possibly the product of RMS volts out times RMS amps out, but it is never mentioned in any engineering books of any kind. Probably it relates to steady-state watts at some distortion level.
Most of these have little, if any, technical merit at all. They are pure marketing hype coined by marketing people because they think people that don't know any better will be impressed by the technobabble. In some cases they make some effort to tie them to something that might possibly have a definition -- such as the peak power that a speaker could absorb for no more than one microsecond without damage -- so that they have something to baffle the courts if they ever get sued, but in most cases they have never actually measured anything related to it.

#### BobTPH

Joined Jun 5, 2013
2,419
The thing that makes it even more laughable is that, with reasonably efficient speakers, in a home environment, 25W is more than enough to listen to music at any level that is not painful.

Bob