• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

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

I have said that high-power RF amps often include intermittent power ratings with on and off (cool-down) duty cycle periods specified. Very common, and would work with the intent (I think) of the FTC rule: continuous power rating, then add a peak power rating that is adequately defined (e.g. the IHF 20 ms burst test) for headroom. You are reading too much into my post without reviewing prior context. Which is the same problem I have and why I should really just stay out of this mess; I am too lazy to post a book with all relevant experience, and then end up being lectured because my responses are either not clear or insufficiently detailed, about a topic I appreciate but realistically is just a bunch of keyboard warriors (myself included) whining about.

I have not renewed my Ham license in many years, another expensive hobby I have not gone back to, but have plenty of experience with Ham radios, commercial radio/TV systems, medical transmitters (e.g. 60 MHz ultrasound scanners), and government (military and otherwise) systems. I like seeing a continuous power rating as it has implications for other things like thermal management, then a headroom spec based on (defined) short-term output, would cover amplifiers for music and other (e.g. radar, communication, telemetry) applications. A radar transmitter is a good example of a design having very high peak power with much lower continuous power ratings. That is why the audio comparison. And you have already provided example where continuous power matters.

My argument with the FTC spec is lack of a clear definition both in scope and compliance testing. I think I have been consistent but this has gone on for so long I am sure someone could find something somewhere. If the FTC opens up a new comment period, I will contribute as I did last time. In this case, I think part of the problem is that people with knowledge of test standards assumed a base experience level not reflected in the final rule.
Believe me, Don, your bona fides did not need to be established from my perspective. This wasn't about expertise, however, but about what the FTC should do, if anything, to aid uneducated consumers in making choices in the market. The rule they landed on isn't that relevant to consumer applications, and that's the root of the problem from my perspective. That is one reason why it's so hard to measure as they have described it--a rule closely traced to consumer applications would be far easier to test. Use cases are easier to draw requirements from when they are realistic, and properly formulating requirements demands testability. Did that sound like lecturing? If so, I apologize--I teach systems engineering processes and can't help it.

And I have never been opposed to continuous power testing, if the signal being tested is relevant to the use case. The FTC condition isn't that, and it has never seemed to me that the power ratings that comply with it will reliably tell uneducated consumers which amp will make their music louder, especially within a factor of 2 or so.

Rick "just a guy" Denney
 
I don’t see anyone suggesting that a single FTC value should replace all the others.
I would hope not, but the way the rule is written, the FTC-compliant number has to be the dominantly displayed number, and the only number shown if there's only one number. I just don't think it's the rating that comes closest to telling consumers what they want to know, and that will lead to confusion in the market.

Rick "going back to the FTC's purpose for existing" Denney
 
I would hope not, but the way the rule is written, the FTC-compliant number has to be the dominantly displayed number, and the only number shown if there's only one number. I just don't think it's the rating that comes closest to telling consumers what they want to know, and that will lead to confusion in the market.

Rick "going back to the FTC's purpose for existing" Denney
I think the FTC just needs to find a middle ground that is more informative than just testing @ 1kHz, but easier to test than what they described. Perhaps testing at three frequencies, 100 Hz, 1kHz and 5kHz will do the job. Pma's (OP) test examples more or less show the claimed performance "issues" the FTC is trying to collect to inform the customer. Issues like significant increase in distortion at frequencies higher/lower than 1 kHz. In such cases, the amp should be derated for THD and/or power.

And then there is the 5 minutes at rated power. A likely response to over invasive nanny circuits like on the Onkyo RZ50.....35 seconds is not enough to claim the rated power. The funny thing is that Onkyo has a fan (unused to extend this time) and runs relatively cool. Nevertheless, year after year they do nothing about it. Maybe this FTC spec will force them.
 
Last edited:
I would hope not, but the way the rule is written, the FTC-compliant number has to be the dominantly displayed number, and the only number shown if there's only one number. I just don't think it's the rating that comes closest to telling consumers what they want to know, and that will lead to confusion in the market.

Were you, or any other of the tens of millions of customers confused about power ratings post-1974 FTC Amplifier Rule? For a good 20 years the manufacturers played ball. At least 2 decades where consumers were getting what they paid for.

Amir's public comments encouraging the law be ignored altogether are disappointing, but hardly unexpected. After all, he's 'famous' for testing cheap amplifiers in little boxes with exaggerated power claims. The entire category is ASR's bread and butter.

As for the ridiculous back and forth here, the rule is just as clear today as it was 50 years ago when enacted. The rated power shall be attainable at any frequency between 20Hz and 20kHz, now with a THD of less than 1%. That means as a manufacturer, you'd better ensure your product can hit those frequency extremes at rated power and stay within spec. Stop the cherry-picking. And 1% THD is not even high fidelity, so it's pretty low bar.

Hopefully there will be something left of the FTC going forward..
 
What leads you to believe that some other competitors aren't complying? It feels like you're sitting on some insider knowledge that I’m not aware of, and it doesn’t sit well with me, as it suggests, going back to your speeding reference, that if others are speeding, it’s acceptable for me to do the same.
You darn well better be aware of seeing how many times I and others have said this: the amplifier regulation is NOT new. It was enacted into law back in 1974. So for 50 years, the obligation has been there to comply with FTC. Yet we see scant evidence of compliance with it today, nor any sign that any company, ever, has being penalized for violating it.

The only thing new is that FTC has updated the regulation. Not that it has been placed there for the first time.

It is the height of silliness to think that companies that ignored the much lower bar of original FTC regulation would now jump and start following the new.

As for speeding, I am sure you have done so because of laxed enforcement. Everyone has. There, you don't even have a financial motive to do so. Yet you do. And do more of it if others are speeding.

FTC could have gotten enforcement by creating a proper spec where I and other reviewers would welcome performing the validation for it. I am already there with a bunch of tests that easily cut through empty power claims. With us doing the policing for them, and them not handing out fines, this regulation will go nowhere.
 
Amir's public comments encouraging the law be ignored altogether are disappointing, but hardly unexpected. After all, he's 'famous' for testing cheap amplifiers in little boxes with exaggerated power claims. The entire category is ASR's bread and butter.
You are confused. I provide testing that shows their actual capabilities and it is those capabilities that have impressed consumers. Not what empty power numbers they put on their web pages.

If a product doesn't perform well, I call it on that. By the same token, when the government regulation is flat out nonsense, I call that as well. I can do that because I don't have a stake in this fight. You do however since you still cherish tens of pounds of heatsink, attempting to cool totally inefficient power amplifiers based on century old topologies. But even there, you haven't shown us how many of those amps can pass the new regulation. Nor has a single company changed its website to show new FTC numbers.

So excuse me if I don't value your opinion in this matter.
 
You are confused. I provide testing that shows their actual capabilities and it is those capabilities that have impressed consumers. Not what empty power numbers they put on their web pages.

If a product doesn't perform well, I call it on that. By the same token, when the government regulation is flat out nonsense, I call that as well. I can do that because I don't have a stake in this fight. You do however since you still cherish tens of pounds of heatsink, attempting to cool totally inefficient power amplifiers based on century old topologies. But even there, you haven't shown us how many of those amps can pass the new regulation. Nor has a single company changed its website to show new FTC numbers.

So excuse me if I don't value your opinion in this matter.
I believe that one of the best threads ever will be an actual comparison of the usual measurements we see around (similar with the existing yours) with a set embracing not the letter but the meaning of the rule (some selected freqs within a reasonable BW,preferably at the edges of the spectrum) for a sane 30sec to one min.
Scrap the 5 min. one of course.

Visuals are always stronger,and plots comparing those will be super interesting.
 
I believe that one of the best threads ever will be an actual comparison of the usual measurements we see around (similar with the existing yours) with a set embracing not the letter but the meaning of the rule (some selected freqs within a reasonable BW,preferably at the edges of the spectrum) for a sane 30sec to one min.
Scrap the 5 min. one of course.

Visuals are always stronger,and plots comparing those will be super interesting.

Look, when I've got nothing better to do than heat up a few amplifiers, I'll happily run some frequency limit full power tests for 5 minutes each at or below the rated distortion (published) for some vintage amps I have lying around here. I'll pick some where they published fully compliant 1974 FTC 20-20k power/THD figures.

My lab bench has a dismantled NAD M-22 (smoked-up SMDs in Hypex modules) on it at the moment, I'm hopefully able to repair. So the amplifier fun tests will have to wait. :)
 
My lab bench has a dismantled NAD M-22 (smoked-up SMDs in Hypex modules) on it at the moment, I'm hopefully able to repair.
Nice amp. I downloaded the service literature and it was of impeccable quality. Off topic but a quick question. Is it possible to wind up something like this with a variac and ammeter? Or are you going to use the lightbulb method? I've never tested a class D amp like this before so I'm not familiar with protocol. What is the danger zone like @ first startup on this unit?
 
Last edited:
Nice amp. I downloaded the service literature and it was of impeccable quality. Off topic but a quick question. Is it possible to wind up something like this with a variac and ammeter? Or are you going to use the lightbulb method? I've never tested a class D amp like this before so I'm not familiar with protocol. What is the danger zone like @ first startup like on this unit?

No variac or DBT for SMPS supplied, micro controlled (three in this amp) amplifiers like this. A whole other ball-game with a pile of external current limited variable PSUs. Much safer to run an amplifier you are repairing from external supplies until you are 100% certain all the faults are rectified. You don't want to kill the SMPS you just repaired... Then you can connect its "own" supply back up. This amp can run externally for testing purposes once repaired, with 7 supplies.
 
No variac or DBT for SMPS supplied, micro controlled (three in this amp) amplifiers like this. A whole other ball-game with a pile of external current limited variable PSUs. Much safer to run an amplifier you are repairing from external supplies until you are 100% certain all the faults are rectified. You don't want to kill the SMPS you just repaired... Then you can connect its "own" supply back up. This amp can run externally for testing purposes once repaired, with 7 supplies.
That's what I was wondering. Very technical and full of danger danger. :D Good luck with that for sure. :D
 
Hardly. The industry is confused. Go read JEITAs proposal to the FTC back in November.
I read their response and believe it brings up a number of valid points. What about JEITAs response is confused?
 
Look, when I've got nothing better to do than heat up a few amplifiers, I'll happily run some frequency limit full power tests for 5 minutes each at or below the rated distortion (published) for some vintage amps I have lying around here.

Will this be yet another vintage amp test you'll forever be in the process of getting around to, or will you actually do it sometime in the foreseeable future?
 
Hardly. The industry is confused. Go read JEITAs proposal to the FTC back in November.
You mean they also say your stance is wrong. Their comments bust through the regulation, showing in different ways why it is broken. I especially love this:

"- Because there is no consistency between the previous and new Rule, the same output power ratings cannot be used. There are cases where the amplifier output of the same product changes from "50W" to"0W", although sound is being produced,"

What they didn't do right is to make an alternate proposal and get their members to agree with it.
 
Look, when I've got nothing better to do than heat up a few amplifiers, I'll happily run some frequency limit full power tests for 5 minutes each at or below the rated distortion (published) for some vintage amps I have lying around here. I'll pick some where they published fully compliant 1974 FTC 20-20k power/THD figures.
So you want me to sign up to run such tests over and over again when you find even doing it once too boring or time consuming???
 
So you want me to sign up to run such tests over and over again when you find even doing it once too boring or time consuming???

If you saw my lab bench at the moment, you'd understand. :)

Once I move it all into one of the spare rooms (huge job), I'll have three suitable desk/bench surfaces and two distinct test "stations". The work and test areas have been shared forever, but now the boys are all grown up I can have one of their rooms. Ha.

In Australia, there is no such thing as a "basement" like you guys seem to all have.

Basically, I want a much bigger house with a separate "lab", but the views across the valley into the mountains are too hard to give up.
 
I would hope not, but the way the rule is written, the FTC-compliant number has to be the dominantly displayed number, and the only number shown if there's only one number. I just don't think it's the rating that comes closest to telling consumers what they want to know, and that will lead to confusion in the market.

Rick "going back to the FTC's purpose for existing" Denney
Which of the current peak power rating methods do you think comes closest to being clear and understandable for consumers?
Remember, the manufacturer can disclose as many ratings they choose.

You darn well better be aware of seeing how many times I and others have said this: the amplifier regulation is NOT new. It was enacted into law back in 1974. So for 50 years, the obligation has been there to comply with FTC. Yet we see scant evidence of compliance with it today, nor any sign that any company, ever, has being penalized for violating it.

The only thing new is that FTC has updated the regulation. Not that it has been placed there for the first time.

It is the height of silliness to think that companies that ignored the much lower bar of original FTC regulation would now jump and start following the new.

FTC could have gotten enforcement by creating a proper spec where I and other reviewers would welcome performing the validation for it. I am already there with a bunch of tests that easily cut through empty power claims. With us doing the policing for them, and them not handing out fines, this regulation will go nowhere.

I know, of course, that the FTC amplifier rule has been in place since 1974, and I’ve previously used this fact to argue that it should be relatively easy for manufacturers to comply, given that it has been followed for decades. I have also provided examples of specification sheets to support this argument.
The recent update is still a meaningful change. It not only modernizes the standard but also comes alongside new FTC regulations targeting deceptive reviews, undisclosed endorsements, and improper incentives. These additions address a long-standing issue in the audio industry which is misleading marketing that has allowed exaggerated performance claims to persist unchecked.

A major reason companies have been able to avoid compliance with the amplifier rule for so long is, in my opinion, the ecosystem of bad-faith reviewers, undisclosed sponsorships, and permanent loan arrangements that seriously blur the line between independent evaluation, review and testing and paid promotion. The new FTC rules directly challenge these practices, prohibiting fake reviews, company-controlled "independent" review sites, and the suppression of negative feedback through legal threats or intimidation. This means manufacturers can no longer rely on hand-picked reviewers to echo their inflated claims without clear disclosure.

The concern about enforcement is valid, as previously acknowledged, but dismissing the regulation entirely ignores how these combined measures could finally curb misleading marketing. With stricter oversight on both performance claims and the way they are reinforced through reviews, theres potential for real accountability. Instead of relying solely on companies to self-police or independent testers to catch false claims, the FTC is setting up a framework to prevent deception from multiple angles. If properly enforced, this could mark a turning point in how consumers assess amplifier performance -one based on verified, transparent information rather than marketing spin, manipulation and "bought" reviewers.
 
You mean they also say your stance is wrong. Their comments bust through the regulation, showing in different ways why it is broken. I especially love this:

"- Because there is no consistency between the previous and new Rule, the same output power ratings cannot be used. There are cases where the amplifier output of the same product changes from "50W" to"0W", although sound is being produced,"

What they didn't do right is to make an alternate proposal and get their members to agree with it.

Did you see they only want THD, not THD+N?
 
If you saw my lab bench at the moment, you'd understand. :)

Once I move it all into one of the spare rooms (huge job), I'll have three suitable desk/bench surfaces and two distinct test "stations". The work and test areas have been shared forever, but now the boys are all grown up I can have one of their rooms. Ha.

In Australia, there is no such thing as a "basement" like you guys seem to all have.

Basically, I want a much bigger house with a separate "lab", but the views across the valley into the mountains are too hard to give up.
When I went from 1 lab workstation to 2 dedicated workstations things where wayyy better and I still could use one more and make more money. You have enough gear to populate 2 or 3 workstations and you might as well build it.
 
Back
Top Bottom