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

[olieb]

Let's not turn this into political ddebate.

You are kind of funny.
Complaining about others, when you started this and you continue it.

But back to topic.
From the FTC rule

Any power level from 250 mW to the rated power shall be obtainable at all frequencies within the rated power band of 20 Hz to 20 kHz without exceeding 1.0% of total harmonic distortion plus noise (THD+N) at an impedance of 8 ohms 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. https://www.ecfr.gov/current/title-16/chapter-I/subchapter-D/part-432

"shall be obtainable" - how can this be tested at all?
The way I read it, to test for a frequency you are supposed to apply full rated power for 5 min at a certain frequency and then test for THD+N at that frequency (at different power levels).
"All frequencies" sounds quite a lot. And so does "any power level". I am surprised they did not say "at all impedances between 3Ω and 8Ω", too.
Seems like an unpractical amount of testing. Maybe the FTC should think about giving a more precise testing procedure, that can actually be done. I am sure the experts there know how to do it.
But even then giving "rated power" as the minimum of power at all measured frequencies (including 20kHz) does not makes much sense for music, but hey, what do I know.
Where am I wrong?

 

[Multicore]

Your readers are happy with the status quo and this is important.

Speak for yourself, not for me. To say that I am happy with the status quo is misleading. And to make judgements based on this presumption is bad-faith rhetoric in the strawman mode.

I am satisfied that the FTC tests do not provide a sensible resolution to a problem that has persisted in this conflicted state for decades. I have found this thread interesting and for me it has made clear that nobody knows(*) how to specify a test protocol that a) is really meaningful for normal use because normal use is undefinable except statistically with large variance and wrapping an envelope around that variance involves tradeoffs with real consequences, and b) would satisfy everyone.

What I see is that some people want a torture test in Amir's amp test suite and argue that the FTC spec is the right one. Some of them argue that lack of this makes Amir a not-credible reviewer. Speaking for myself, I agree with neither of those.

(* clearly including the FTC)

 

[Sokel]

Speak for yourself, not for me. To say that I am happy with the status quo is misleading. And to make judgements based on this presumption is bad-faith rhetoric in the strawman mode.

I am satisfied that the FTC tests do not provide a sensible resolution to a problem that has persisted in this conflicted state for decades. I have found this thread interesting and I think it makes clear that nobody knows(*) how to specify a test protocol that a) is really meaningful for normal use because normal use is undefinable except statistically with large variance, and b) would satisfy everyone.

What I see is that some people want a torture test in Amir's amp test suite and argue that the FTC spec is the right one. Some of them argue that lack of this makes Amir a not-credible reviewer. Speaking for myself, I agree with neither of those.

(* clearly including the FTC)

I mostly agree.
If I were to choose couple of freqs of extended test I would choose 20Hz ,100Hz and 6.63kHz.All with 20kHz BW,no more so everyone will be happy.
That would tell some of the story to me.
Or a multitone with a tight CR.

 

[Multicore]

I mostly agree.
If I were to choose couple of freqs of extended test I would choose 20Hz ,100Hz and 6.63kHz.All with 20kHz BW,no more so everyone will be happy.
That would tell some of the story to me.
Or a multitone with a tight CR.

I'm open to ideas. I think a lot of us are.

I remember discussing the same question of real use cases, Peak Watts, Music Watts, etc. back in the early 80s with my dad (who had a set of burned out Quad II & ELS in the garage that he'd used before starting a family) when I was a teen and getting interested in audio. He was an engineer and took it as a teaching opportunity. He understood how such pseudo-Watts were not persuasive but was clear that standard bench tests for a standard definition of, say, Home Entertainment Amplifier Watts is going to land somewhere on a scale between unrealistic torture test and bullshit.

For my own purposes, I think Amir's tests as they are today are a very useful contribution. I guess Bryston might not think they adequately represent the difference between their products and those of Aiyima. I would agree. But this isn't a good reason to be ungrateful and even insulting as some have been. And beating him over the head with this crummy FTC test and all the attendant legalistic and moralistic blather isn't, in my opinion, conducive to developing a better amp power spec and corresponding test protocol.

 

[RickS]

This thread has gotten repetitive and still suffers from the same basic issue Amir articulated more than 700 posts ago - a need to step back and define the problem we want to solve. This confounds me somewhat as Amir's amplifier power testing has evolved over time and is pretty robust already. As Amir indicated, he feels there is some room for automated functional/exception testing. As with his current tests, the intent is that these new tests would be non-destructive. So please focus your comments with that in mind. @Astoneroad ‘s poll clearly indicates that members rather see more speaker testing than amplifier testing too. So, any new amp testing needs to be mindful of Amir's bandwidth as well.

Finally, I posted earlier that ASR should be able to do better than the FTC. Am going to amend that to Amir already does better than the FTC. In fairness, will credit Audioholics, Soundstage and Stereophile for comparable measurements. Even without a major technical team, the FTC did not have to look far for good examples of power testing that has gone on for decades while they vacillated. This community does the technical aspect better than the FTC already.

 

[Mnyb]

Speak for yourself, not for me. To say that I am happy with the status quo is misleading. And to make judgements based on this presumption is bad-faith rhetoric in the strawman mode.

I am satisfied that the FTC tests do not provide a sensible resolution to a problem that has persisted in this conflicted state for decades. I have found this thread interesting and for me it has made clear that nobody knows(*) how to specify a test protocol that a) is really meaningful for normal use because normal use is undefinable except statistically with large variance and wrapping an envelope around that variance involves tradeoffs with real consequences, and b) would satisfy everyone.

What I see is that some people want a torture test in Amir's amp test suite and argue that the FTC spec is the right one. Some of them argue that lack of this makes Amir a not-credible reviewer. Speaking for myself, I agree with neither of those.

(* clearly including the FTC)

+1 .

But I’m not against anyone doing these FTC like tests they are also a data point and informative .

Reviewers has the easiest part manufacturer have to be more strict of they wish to quote compliance .

But they have bigger problems they need to retest already designed products on sale right know ( reading Hartman’s comment about the retroactive part of the ruling ) and possibly change the packing( if specs are written on them ) and print new manuals ? This is going to cost and will be moved onto the end customers

 

[Multicore]

This thread has gotten repetitive and still suffers from the same basic issue Amir articulated 700 posts ago - a need to step back and define the problem we want to solve.

Yes, and yes. It also being used to push a variety of agendas, some of which are entirely unrelated to "the problem we want to solve".

If we want to define that problem, or discuss specific ideas for definitions and tests, I would prefer a new thread or threads in which the thing to be discussed is presented in the OP. Given some of the rhetoric in this thread, its repetitive nature, and its lack of focus, I'd rather see this one closed.

 

[tmtomh]

Apologies, but that feels like a weak excuse, in my opinion. Are you really suggesting they’re avoiding engagement because they’re afraid of what John might say? Doesn’t that sound a bit far-fetched?
John is being put on such a pedestal he’d need a helicopter to reach it.

I agree with Sokel -some input from them would be valuable.

You’d think assemblers and manufacturers would want to advocate for less restrictive rules than those proposed by the FTC. Why wouldn’t they join the discussion and present real-world examples from their own testing to support their case? That seems like the logical way to influence the market and lobby effectively.

Instead, their silence leaves everything open to speculation. (And I really hope it’s not because they’re afraid of John!)
One could look through the comments the FTC received during the regulation hearing to see where they stand. However, given how the rules ultimately turned out, it seems they had their chance to make a case but failed to persuade the FTC to make any changes.

No, I'm not suggesting they're afraid. I'm suggesting that there are many, many threads here at ASR where these questions can, and do, get discussed - at length and in great detail.

I'm suggesting, instead, that the topic of this thread is an argument, which has descended from a technical debate into an ad hominem fight about ethics and morality - over the FTC rule.

This thread and all the other threads here at ASR are sandboxes. The amp makers who frequent these forums do - and should - tolerate people pissing in their sandbox, for example comments in the discussion thread of a review of one of their products. But it's quite another matter for them to look at a sandbox, see that it's already full of urine, and say, "You know what would be a great idea? Jumping into that!"

No one - not an amp maker, not an industry veteran, not a random individual member here - is required or obligated to participate in any particular discussion in order to "prove" their bona fides to you or Pavel or John or anyone else. The whole idea that amp makers or anyone else needs an excuse not to participate in this thread is ridiculous on its face.

 

[Old_School_Brad]

No, I'm not suggesting they're afraid. I'm suggesting that there are many, many threads here at ASR where these questions can, and do, get discussed - at length and in great detail.

I'm suggesting, instead, that the topic of this thread is an argument, which has descended from a technical debate into an ad hominem fight about ethics and morality - over the FTC rule.

This thread and all the other threads here at ASR are sandboxes. The amp makers who frequent these forums do - and should - tolerate people pissing in their sandbox, for example comments in the discussion thread of a review of one of their products. But it's quite another matter for them to look at a sandbox, see that it's already full of urine, and say, "You know what would be a great idea? Jumping into that!"

No one - not an amp maker, not an industry veteran, not a random individual member here - is required or obligated to participate in any particular discussion in order to "prove" their bona fides to you or Pavel or John or anyone else. The whole idea that amp makers or anyone else needs an excuse not to participate in this thread is ridiculous on its face.

Sure, I didn’t say they’re obligated to share their thoughts, only that it would be nice to hear their opinions on the matter. That’s all. I just found it odd that you seemed to suggest it was due to some vocal individuals that they chose not to. I understand that the premise of the thread might be off-putting, but as you mentioned, they are like sandboxes. As it stands, I think it contains a lot of interesting ideas and opinions.
There are some manufacturers on the forum. Don’t you think they could share valuable insights that might help in developing more effective test regimes?

 

[Maciekw]

Sure, I didn’t say they’re obligated to share their thoughts, only that it would be nice to hear their opinions on the matter. That’s all. I just found it odd that you seemed to suggest it was due to some vocal individuals that they chose not to. I understand that the premise of the thread might be off-putting, but as you mentioned, they are like sandboxes. As it stands, I think it contains a lot of interesting ideas and opinions.
There are some manufacturers on the forum. Don’t you think they could share valuable insights that might help in developing more effective test regimes?

They don't want to participate in trolling. Or they don't want to get into discussions that are offensive to others. Whence accusing others of dishonesty is anything but rude.

 

[JustJones]

The only thing I'm curious about is whether the FTC will grant the CTA petition and reopen for clarification and amendment. You can glean a bit of the thinking from a couple of manufactures who commented on the petition. Reading a bit between the lines it appears Masimo is thinking of abandoning power ratings in the US and just list them on products sold in the rest of the world. Harman looks like they might be leaning that way as well. JEITA would like to ignore the FTC rules and use IEC instead. I doubt any are leaning towards building tanks with fans and raising prices fourfold.

 

[tmtomh]

Sure, I didn’t say they’re obligated to share their thoughts, only that it would be nice to hear their opinions on the matter. That’s all. I just found it odd that you seemed to suggest it was due to some vocal individuals that they chose not to. I understand that the premise of the thread might be off-putting, but as you mentioned, they are like sandboxes. As it stands, I think it contains a lot of interesting ideas and opinions.
There are some manufacturers on the forum. Don’t you think they could share valuable insights that might help in developing more effective test regimes?

They can absolutely share valuable insights - and they do, and I presume they will continue to do so.

But when the framing and tenor of the discussion is virtually guaranteed to result in them getting attacked and their personal and/or business integrity getting questioned, why would they want to offer their insights in that particular environment?

The responsibility for the environment of this thread lies with Pavel and John. And one of the reasons the environment is as it is, is that neither one of them is willing to take one shred of accountability for any misstatements, overstatements, omissions, or errors in their claims and accusations. They are not even willing to acknowledge them.

Personally, that doesn’t deter me from weighing in here anyway. But I don’t earn my livelihood from making and selling the products they’re attacking, so it’s a no-stakes decision for me to participate in this thread. And unlike an amp maker I am just an individual hobbyist so I do not look petty or unprofessional or like I’m “punching down” if I directly engage with and call out those two members’ bad (IMHO of course) behavior in how they comport themselves here.

If someone started a new thread that asked for input or insights from amp designers and assemblers about testing amps, I’d guess that some of the familiar industry folks and vendors who participate here would indeed provide their insights in such a thread.

 

[Multicore]

I understand that the premise of the thread might be off-putting

I don't think it's the premise of the thread that's off-putting at all. Many of the posts in the thread however are very off-putting. I think this sandbox is now so polluted it's not a suitable vehicle for serious technical discussion.

 

[Sokel]

I'm afraid that the sentiment of this thread comes from cases like @miero ,@EddNog ,etc.These people got clearly mislead about the power abilities of the B100 for example,and it's not like they want to drive ESLs,at one case are tiny Kef Metas,hipassed at 100Hz and with a non-cannibal listener.

If it's real world use we like to see tested FTC maybe not be the way but neither the former tests and ratings are.It's that simple,and no one can talk its way out of it.

 

[Multicore]

There are some manufacturers on the forum. Don’t you think they could share valuable insights that might help in developing more effective test regimes?

Sealioning. This thread is not even about developing more effective test regimes. It's about bashing class D amp products, discrediting Amir for reviewing them positively, and insulting ASR participants who agree. Those using this thread to pursue these goals are not likely to be persuaded otherwise by a vendor chiming in.

Developing more effective test regimes sounds fine to me and I imagine it does to many others. If it were up to you to organize that, how would you set about it? Would you want it to be like this thread?

 

[Sokel]

It's about bashing class D amp products,

This thread started after testing a class B amp,the Topping B100,not class D.
Bashing is probably about size.

 

[Multicore]

This thread started after testing a class B amp,the Topping B100,not class D.

Correct. I was inaccurate on that detail.

 

[gnarly]

I switched to proaudio amps about 20 years ago, and haven't really thought much about home audio amps since.
But this thread has made me realize that without Class D, the size amps I use would simply not be available.
AC line service, and efficiency makes it so.

A 2-ch QSC PL380 I use for subs, clips at 2500W per ch @ 4 Ohms. It will hold 2000W for 4 seconds, 1050W after 8 secs, and depends on the stiffness of AC line thereafter.
This is on a single 120V ac line.

The McIntosh 75th anniversary pair of 1000W monoblocs is the highest wattage conventional amp I could quickly find.
Each of the monoblocs requires a separate AC line, as does an accompanying module that goes with the blocs.
Each monoblocs is all you can put on a 120V AC line.

As delightful and outrageous as the McIntosh is, it would simply not allow me to run my subs at the same unclipped SPL, as the QSC amps does.

Must also say, the more I think about it, the 5min FTC rule is plain out of touch with todays reality and technological advancements.
Would also like to see someone actually test, even a small amp, at full rated power for 5min.
And might pay to see the big McIntosh rig run all out for the 5 min test ...provided I know where the exit door is
(haha, I'd expect AC breaker will save the day)

 

[Sokel]

I switched to proaudio amps about 20 years ago, and haven't really thought much about home audio amps since.
But this thread has made me realize that without Class D, the size amps I use would simply not be available.
AC line service, and efficiency makes it so.

A 2-ch QSC PL380 I use for subs, clips at 2500W per ch @ 4 Ohms. It will hold 2000W for 4 seconds, 1050W after 8 secs, and depends on the stiffness of AC line thereafter.
This is on a single 120V ac line.

The McIntosh 75th anniversary pair of 1000W monoblocs is the highest wattage conventional amp I could quickly find.
Each of the monoblocs requires a separate AC line, as does an accompanying module that goes with the blocs.
Each monoblocs is all you can put on a 120V AC line.

As delightful and outrageous as the McIntosh is, it would simply not allow me to run my subs at the same unclipped SPL, as the QSC amps does.

Must also say, the more I think about it, the 5min FTC rule is plain out of touch with todays reality and technological advancements.
Would also like to see someone actually test, even a small amp, at full rated power for 5min.
And might pay to see the big McIntosh rig run all out for the 5 min test ...provided I know where the exit door is
(haha, I'd expect AC breaker will save the day)

The thing is claims.
Here's one of 8381A's pair of amps:

A pair of them is suppose to do 6kW.So 3kW each.
Now look at the electrical rating and the 10A mains socket (the 16A one is different,blades are oriented horizontally)
Yes,it may have a large bank of caps inside,etc,haven't look the guts.
But 3kW?

 

[miero]

I'm afraid that the sentiment of this thread comes from cases like @miero ,@EddNog ,etc.These people got clearly mislead about the power abilities of the B100 for example,and it's not like they want to drive ESLs,at one case are tiny Kef Metas,hipassed at 100Hz and with a non-cannibal listener.

Actually I'm happy with the B100 amplifiers, but I'm using them in a specific scenario for the 2-way active horn speakers to drive only the high-frequency drivers (109 dB sensitivity, ~800Hz high-pass). In my living room, even 5 watts is more than I need.

The low noise of the B100 combined with the ability to select the unity gain, allows me to connect the driver directly to the amplifier and not hear any noise coming from the driver. The source is MiniDSP Flex with balanced outputs.