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Power amplifier tests with respect to FTC: 16 CFR Part 432 (July 5, 2024) requirements on output power claims

I have neither signs nor stickers (nor a minivan). Nor am I wearing a tinfoil hat. All I have is a well-equipped test lab with a variety of loads and environmental test chambers. And I will use them as I see fit and logical without worry about the Feds descending on me.
...and rightfully so,you don't sell amps,you just test them.
What I wonder about is the gravity of opinions.Will for example your complain (been an expert) to them about an amp be heard with the same attention with mine who know scrap? Obviously it shouldn't.
 
A watt is a watt is a watt.

I say, all amplifiers, henceforth, shall be specified in horsepower. At least they have some staying power and don't drop dead at the first step.

All this BS started appearing as stimuli signals reduced from continuous, to fewer and fewer cycles. The crazy "current" numbers for Class Ds (and plenty of conventional amps) are for single cycles into virtual short circuits (<0.1R).

The promotional impact is significantly reduced if the manufacturer is required to disclose a rating of 0.0335 HP (per channel).
 
The only thing that will cause any FTC action would be major manufacturers ratting on each other or a class action lawsuit brought by consumers who had monetary loss. Individual complaints are tossed in what's effectively a "dead letter box".
 
Will for example your complain (been an expert) to them about an amp be heard with the same attention with mine who know scrap?
I am indifferent to the FTC. When I run into problems with an amp, it goes into my review and is published for the benefit of consumers.

FWIW, I have only had one amp fail under test conditions; it was a headphone amp and the failure was duly noted in the review. The manufacturer was unhappy that I actually tested to their published specs and has made sure to never send me any more product.
 
...and rightfully so,you don't sell amps,you just test them.
What I wonder about is the gravity of opinions.Will for example your complain (been an expert) to them about an amp be heard with the same attention with mine who know scrap? Obviously it shouldn't.
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J.A. in 1989 - we are back in circles.


…. and now


The later Atkinson article reveals a hallmark feature of all our best ;) federal regulations - a loophole where manufacturer can claim “This rating was not tested under the FTC standard”.

Further research reveals, the FTC made an exception to the regulation for powered subwoofers but not for powered speakers.:facepalm: If you are still wondering, how a powered subwoofers were even considered, me too. By proxy this would imply that embedded amplifiers are somehow included under the rule.

As Amir’s current amp power testing is already extensive, the real ASR value add would be to offer a better amplifier power metric than the FTC regulation. Am personally fine with a spider chart but could also be presented as an overall rating for simplicity's sake. Forcing a single dimensional metric on a multifaceted feature is the FTC’s main technical failing in my opinion.
 
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What ASR can easily do is to promote and reward manufacturers that provide better specifications. For example by having special badges for honest specification and for a specification inflated for marketing purposes.
 
I honestly appreciate the push by you and @pma to include some testing for continuous power capability, but lets keep it sane. FTC is not going to go after reviewers for being limited in what they test and report. What other reviewers with testing are doing the 5 min 20-20k test?
Not many, that's correct. However, @John Atkinson at Stereophile has always been running pre-conditioning, historically at 1/3 rated power into 8ohm, later at 1/8, for one hour, sometimes 30 minutes (AVR). You may check Stereophile amplifier tests. I find them most honest of public audio reviews. This test is IMO even more revealing than the 5 minute rated power test. One example:


I measured the Exposure 3010S using Audio Precision's top-model SYS2722 system (see www.ap.com) for most of the tests, with some use made of the older AP System One. As usual, I preconditioned the amplifier by running both channels at one-third power into 8 ohms, which maximally stresses an amplifier with a class-B or -AB output stage. The normal preconditioning period is one hour, but the Exposure turned itself off after just 20 minutes. While the chassis was warm, the area of the top cover above the internal heatsink was almost too hot to keep my hand on. After the amplifier had cooled down, I turned it on again, and all seemed well. But this does suggest that the Exposure's heatsinking is inadequate for sustained use at levels around 40Wpc, which could well happen if the amplifier is used to provide music at a party.
[bold emphasized by PMA]
Needless to say that amplifiers mostly pass the test. But yes, he does not test the toy boxes.
 
FWIW, AI says the 5 minute test should be performed at 6 frequencies. I don't know where that comes from. So that would be more than a half hour of testing.

The 5-minute continuous operation test should be performed at each frequency where the amplifier is tested for maximum power output. According to the FTC's guidelines for testing the power output of audio amplifiers, you should test the amplifier at multiple frequencies across the full range of human hearing (20 Hz to 20,000 Hz). Typically, the FTC-recommended frequencies for measuring and testing the continuous power output include:

  1. 20 Hz
  2. 100 Hz
  3. 1 kHz
  4. 5 kHz
  5. 10 kHz
  6. 20 kHz
Therefore, the 5-minute continuous operation test should be performed at each of these 6 frequencies.

Rationale:​

  • 20 Hz and 100 Hz represent the low end of the frequency spectrum, where amplifiers can exhibit challenges in maintaining output power due to the low-frequency demands on the power supply and output stage.
  • 1 kHz is a commonly used frequency to represent mid-range performance, where amplifiers typically perform well.
  • 5 kHz, 10 kHz, and 20 kHz are used to ensure that the amplifier can handle higher frequencies and to evaluate any potential roll-off or distortion at the top end of the audio spectrum.

Procedure:​

For each of these frequencies, the test would be conducted by:

  1. Gradually increasing the signal to the amplifier until it reaches the point of clipping (maximum undistorted output).
  2. Measuring and recording the output power at this point.
  3. Then, maintaining the continuous operation at this maximum output for 5 minutes while monitoring for any distortion, thermal issues, or power drop.
Thus, the 5-minute continuous operation should be performed for each of the 6 frequencies: 20 Hz, 100 Hz, 1 kHz, 5 kHz, 10 kHz, and 20 kHz.
 
Not many, that's correct. However, @John Atkinson at Stereophile has always been running pre-conditioning, historically at 1/3 rated power into 8ohm, later at 1/8, for one hour, sometimes 30 minutes (AVR). You may check Stereophile amplifier tests. I find them most honest of public audio reviews. This test is IMO even more revealing than the 5 minute rated power test. One example:



[bold emphasized by PMA]
Needless to say that amplifiers mostly pass the test. But yes, he does not test the toy boxes.
I don't think he does the preconditioning for Class D. Obviously this is not an extreme stress test for Class D. But anyway I was more asking about the 20Hz to 20KHz 5 minute test.
 
The 5-minute continuous operation test should be performed at each frequency where the amplifier is tested for maximum power output. According to the FTC's guidelines for testing the power output of audio amplifiers, you should test the amplifier at multiple frequencies across the full range of human hearing (20 Hz to 20,000 Hz).
Please let us quote the FTC regulation correctly, to prevent further second guessing debates. There is nothing like "test should be performed at each frequency", it states that "rated power should be obtainable at ..."

Rated power shall be obtainable at all frequencies within the rated power band without exceeding the
rated maximum percentage of total harmonic distortion after input signals at said frequencies have been
continuously applied at full rated power for not less than five (5) minutes at the amplifier's auxiliary input,
or if not provided, at the phono input.
 
FWIW, AI says the 5 minute test should be performed at 6 frequencies. I don't know where that comes from. So that would be more than a half hour of testing.

The 5-minute continuous operation test should be performed at each frequency where the amplifier is tested for maximum power output. According to the FTC's guidelines for testing the power output of audio amplifiers, you should test the amplifier at multiple frequencies across the full range of human hearing (20 Hz to 20,000 Hz). Typically, the FTC-recommended frequencies for measuring and testing the continuous power output include:

  1. 20 Hz
  2. 100 Hz
  3. 1 kHz
  4. 5 kHz
  5. 10 kHz
  6. 20 kHz
Therefore, the 5-minute continuous operation test should be performed at each of these 6 frequencies.

Rationale:​

  • 20 Hz and 100 Hz represent the low end of the frequency spectrum, where amplifiers can exhibit challenges in maintaining output power due to the low-frequency demands on the power supply and output stage.
  • 1 kHz is a commonly used frequency to represent mid-range performance, where amplifiers typically perform well.
  • 5 kHz, 10 kHz, and 20 kHz are used to ensure that the amplifier can handle higher frequencies and to evaluate any potential roll-off or distortion at the top end of the audio spectrum.

Procedure:​

For each of these frequencies, the test would be conducted by:

  1. Gradually increasing the signal to the amplifier until it reaches the point of clipping (maximum undistorted output).
  2. Measuring and recording the output power at this point.
  3. Then, maintaining the continuous operation at this maximum output for 5 minutes while monitoring for any distortion, thermal issues, or power drop.
Thus, the 5-minute continuous operation should be performed for each of the 6 frequencies: 20 Hz, 100 Hz, 1 kHz, 5 kHz, 10 kHz, and 20 kHz.
Hence the conspiracy theories about Mcintosh,Boulder and the shorts used as advisers across the forums :facepalm:
 
Please let us quote the FTC regulation correctly, to prevent further second guessing debates. There is nothing like "test should be performed at each frequency", it states that "rated power should be obtainable at ..."
If I did not know it is impossible I would read the rule as requiring the 5 minute test at all of the infinite frequencies between 20Hz and 20Khz. What makes you think only a single test is required? Don't you think the procedure should be spelled out better?
 
I don't think he does the preconditioning for Class D. Obviously this is not an extreme stress test for Class D. But anyway I was more asking about the 20Hz to 20KHz 5 minute test.
Try for example AIYIMA A07 with 48V PSU with one hour 1/3 power test in both channels. They claim 250W pc, so it would be at 2 x 80W. Did you try? I did 1 x 100W (only one channel loaded) and it did shut down after 1 minute. Would you guys please write down the facts and not your mere opinions?? I have asked for it many times. Or, at least, stay aside without arguing and rather try to learn something. I am missing debates with John Curl ;). And I am the thread starter, so I feel some right to rectify the debate.
 
Try for example AIYIMA A07 with 48V PSU with one hour 1/3 power test in both channels. They claim 250W pc, so it would be at 2 x 80W. Did you try? I did 1 x 100W (only one channel loaded) and it did shut down after 1 minute. Would you guys please write down the facts and not your mere opinions?? I have asked for it many times. Or, at least, stay aside without arguing and rather try to learn something. I am missing debates with John Curl ;).
No I haven't tested any amplifiers this way, but the test is 1/8 of max power, right?

For trying to learn something it would be more helpful if you answer why you are sure the 5 minute test is for just one frequency, instead of telling me not to ask questions.
 
It would be very funny indeed of other things - like stove tops or heaters - were specified like audio amps. "Sure - it's 2 kilowatts!!!" (for 20 milliseconds)
Certaninly there was a time (perhaps still is) that electric motors (e.g., in power tools) seem to have been rather fancifully rated in terms of (horse)power.
1 hp, it will be recalled, is ca. 746 watts. I only write "circa" because good ol' google returns a bit of a range for the conversion. 746 is what I was taught way back when.
 
Try for example AIYIMA A07 with 48V PSU with one hour 1/3 power test in both channels. They claim 250W pc, so it would be at 2 x 80W. Did you try? I did 1 x 100W (only one channel loaded) and it did shut down after 1 minute. Would you guys please write down the facts and not your mere opinions?? I have asked for it many times. Or, at least, stay aside without arguing and rather try to learn something. I am missing debates with John Curl ;). And I am the thread starter, so I feel some right to rectify the debate.

"pre-conditioning was at 2 x 8W/4ohm for one hour, as requested by the FCT document"
Source: https://pmacura.cz/FCT/aiyima_a07_test.htm

the load should be 8 ohms according the FTC requirement ... or not?
 
I just had a brilliant idea. power times time = energy
Establishing a standard criterion, we could rate amplifiers for energy.
Work with me, here!
Let's pick Holst's The Planets.
Set, or specify an output level that gives less than or equal to a specified level of clipping as assessed by THD (let's say 0.1%) across the duration of The Planets.
Hook up the specified dummy load, and play The Planets.
Collect output power data for the entire running time and do the arithmetic.

Sort of like measuring "mixed driving" fuel economy

:cool:
;)
:facepalm:
 
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