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

[RickS]

I had a Class D desktop amp die when I shorted the outputs even though it claimed to have "Perfect protection circuit for overheating, overcurrent, etc." For sure I consider it my fault. But I don't know if protection by itself is the best answer, at least not for everyone.

Which amp was it?

 

[mhardy6647]

I am not outraged. Are you outraged? I will fake some outrage as an excuse to have a beer to calm me down though.

I like your thinking!

 

[pjug]

Which amp was it?

i didn't want to say since it was my fault. SMSL A300. The scheme with grounded + on one of the outputs bit me. I knew about it but trusted my memory on which channel. Memory was shit!

This example is not really on point for the continuous power issue except to say protection can't always be trusted. Also to look at it another way maybe playing these amps at max power for a few minutes will verify that protection is triggered!

 

[RickS]

i didn't want to say since it was my fault. SMSL A300. The scheme with grounded + on one of the outputs bit me. I knew about it but trusted my memory on which channel. Memory was shit!

This example is not really on point for the continuous power issue except to say protection can't always be trusted. Also to look at it another way maybe playing these amps at max power for a few minutes will verify that protection is triggered!

Thanks, not one of the best amps Amir has tested but understand how you feel. I have fixed better amps that failed when shorted too. Without a deep dive, rather than reliability, this is the domain of functional exception testing. I suspect exception testing is more of what Amir recently proposed but need him to be more specific. True reliability testing would be much more work.

 

[Old_School_Brad]

This is where Amir's graphs are useful. Given the measured performance he wrote "Yes, the 300 watt rating is a fantasy..."
What new information would failing the FTC tests add to what he already provided?

That it is a 10-15 W continuous amplifier, not the 55 or 77 W continuous amplifier that even an informed consumer, seeking out third party testing, might expect.

 

[Old_School_Brad]

These devices have robust protection circuits that shut them down if they get too hot. So there should be little worry about short term failure in this regard. Long term failure is another matter one that is not caught by this 5 minute, one time test.

That said, I am interested in tests that perform some level of design verification. My thought was to stress the amp thermally but also check for transient conditions (e.g. power cycles, shorts, etc.). I would then let such a test run overnight and see if it survives. For this to happen, someone needs to step up and build an automated fixture for it. I can't tie up my lab gear this way for this long. Need to connect, push a button and go to sleep and have results tomorrow. Once there, companies can then build such a box themselves or buy it.

I like the idea but see a few challenges with this approach. First, what happens if the device enters protection mode and requires a reset?
What if the device starts sparking? Personally, I wouldn’t feel comfortable leaving a device under stress testing unattended overnight.

 

[restorer-john]

We call this biting your nose despite your face.

You're mixing up your sayings. Also, you cannot bite your own nose. LOL.

The correct saying is "cutting off your nose to spite your face"

In your case, I would use "biting the hand that feeds you". More appropriate.

Your schtick seems to be to act hostile and demand that people run a test you have not run or thought through yourself. This kind of approach doesn't work with me.

Not people. Just you. It's your website and you are the reviewer.

The only category I have ongoing criticism of your methods is amplification. It's also a personal interest of mine and Pavel's. He designs, builds and tests. I repair, restore and test. I do all my testing (often so extensive it's ridiculous) for me (and a small number of people I decide to work on their gear), not for the world at large.

People always want more and more and they want it for nothing. You most likely don't get acknowledgment, letalone any thanks. You might think I'm just one of those people, but you'd be wrong. My contribution here to date has been to help as much as commentate.

The fact of the matter is you need to re-consider your power output testing to come in line with current regulations. I've lost count of all the nice ways I've brought this up over the years, now it's just pigheadedness from you and frustration for me at your increasingly confused responses and vain attempts to shut us down. As you say, that "kind of approach doesn't work with me", either.

But it's Christmas in less than two weeks and I have little interest in having a ongoing fight over FTC regulations and amplifier testing. The rule is in place and is law in the US. It's game over for arguments and time to start following the spirit of it- Christmas that is.

Merry Christmas, Amir.

 

[pma]

Well said, John. At least we tried .

 

[amirm]

I like the idea but see a few challenges with this approach. First, what happens if the device enters protection mode and requires a reset?
What if the device starts sparking? Personally, I wouldn’t feel comfortable leaving a device under stress testing unattended overnight.

I go through a version of this already in the reviews. That is, determining the limits of the device. Once that is established as part of the review, then you test the amplifier up to that limit. The amp would be in an enclosure that flame proof. And can optionally have automatic fire extinguishing devices.

But yeh, it is not a trivial thing to do and hence the reason I said we need to discuss and figure out what to build. And assess if the extra work is worth it.

 

[Old_School_Brad]

I go through a version of this already in the reviews. That is, determining the limits of the device. Once that is established as part of the review, then you test the amplifier up to that limit. The amp would be in an enclosure that flame proof. And can optionally have automatic fire extinguishing devices.

But yeh, it is not a trivial thing to do and hence the reason I said we need to discuss and figure out what to build. And assess if the extra work is worth it.

Well, that's a whole different level. Isn't it a bit like using a sledgehammer to crack a nut? I don't think an over complicated fully automatic, climate-controlled, fireproof, and secure box is really necessary to get the point across or to obtain valuable data.
You’d likely end up in a bind with your insurance and third-party approval over the "24 h. Amplifier Torture Chamber."

K.I.S.S. ?

 

[amirm]

The only category I have ongoing criticism of your methods is amplification. It's also a personal interest of mine and Pavel's. He designs, builds and tests. I repair, restore and test. I do all my testing (often so extensive it's ridiculous) for me (and a small number of people I decide to work on their gear), not for the world at large.

You two suffer from extreme bias in this regard:

You think only class AB amps of the yore are real amps. And nothing as light as a class D amp can be a "real amplifier." The idea that these things have obsoleted the products that came decades before it, is untasteful so you fight and fight. Now you have this FTC bone, thinking those monstrosities of the past have an advantage.

Pavel is forever thinking of proving that he knows how to design amps and others do not. His amplifiers are not class D so like you, if he can find any way to dismiss them as being "real," he will go there. As you, he thinks the FTC rules are the ticket.

Neither one of you has brought any unique knowledge here. Just demanding a random test to be run with zero knowledge what good it will do. Just that it will diminish smaller amplifiers against relics of the past. I get it. You wear that on your sleeves.

My home theater has a 5 channel proceed class AB amp which I think weighs 100 to 120 pounds. Needed two more channels. Put in a 1U Hypex stereo amp and the thing runs cool, while the Proceed is cooking. The stupid thing uses 150 watts or so even in standby so that bias is maintained! I often thinking about pulling out the massive hunk of iron and putting in a 5 channel Hypex and have a much better system for it.

All that aside, the world is happy with where it is. Large number of these amplifiers are being sold and people and satisfaction level is sky high given how reasonably they are priced. This is progress. You two need to adopt the new world and stop advocating that we go back to rotary phones.

 

[amirm]

Well, that's a whole different level. Isn't it a bit like using a sledgehammer to crack a nut?

That would be the analogy I might use with respect to running the FTC test!

I don't think an over complicated fully automatic, climate-controlled, fireproof, and secure box is really necessary to get the point across or to obtain valuable data.
You’d likely end up in a bind with your insurance and third-party approval over the "24 h. Amplifier Torture Chamber."

K.I.S.S. ?

Whatever I do, needs to be proper and defensible. The first time I get challenged on it by a company, I need to be able to tell them how to replicate the issue. This is why I have state of the art, industry approved gear for testing today instead of hobby level stuff.

As for automation, I need it because I can't sit there and run such a test manually. It just takes too much time.

But yes, all this is extra work if we want to do it right. And I am not sure yet if it is worth my time.

 

[JSmith]

At least we tried

It may be an idea to take a step back and separate the reviewer who spent $30K on an analyser, $110K on a Klippel and $20K on that load box who commits his personal time to do something the industry can't seem to do itself, from the manufacturers. You're petitioning (and that was polite) the wrong person/entity on this.

A few have stirred up the FTC, who have made the guideline/rule as clear as mud... the FTC who have almost zero compliance powers and have been challenged successfully in US courts in the last few years making their mandate even weaker. Not to mention there is the rest of the world... not just USA.

Surely there was a more constructive way to have achieved a better and more positive result?

I don't think one member here likes to see companies being deceptive or dishonest... things of that nature are called out here at ASR much more than anywhere else. I've regularly called out misleading power specs and other silliness, as have many other members. ASR testing often shows much less power than advertised, which clearly demonstrates no one is pandering to certain types of amps or their manufacturers.

Surely a better "standard" can be achieved, apart from "chuck it on high for 5 mins Bro"?


JSmith

 

[amirm]

But it's Christmas in less than two weeks and I have little interest in having a ongoing fight over FTC regulations and amplifier testing. The rule is in place and is law in the US. It's game over for arguments and time to start following the spirit of it- Christmas that is.

What you highlighted was for preservation of the old, amplifier rules. NOT new, 2024 regulations. I know because I have read many of the comments. Folks were galvanized to write the FTC and say it should not abandoned the effort. Here is one of many such comments:

"Please hold manufacturers true to their claims when selling equipment to the consumer. It is deceptive to advertise that a product capabilities which are truly lower than said products can actually measure up to. Consumers spend a lot of their hard earned money and should be given what they (consumers) believe they are paying for and actually getting.
Thank you."

I am in violent agreement with this. We want proper and comparable data for consumers. The problem is, FTC staff with no technical knowledge, ran off with substantial changes in the new ruling, while naively thinking they were simplifying/making things better. There was no proper research done by anyone with any expertise as to usefulness of 5 minute max power test at full bandwidth. Or even how to run such a test. This is the problem.

Reading through a ton of comments, I did not see a single one saying let's cook the amp for 5 minutes.

As I have said repeatedly, FTC should have delegated to a professional engineering organization such as AES to draft such standard and then just stamp them into law. FCC does that with SMPTE for television standards. And at any rate, has extremely rigorous process. FTC personnel are simply unqualified to create technical standards with such specificity.

I think this goes beyond the authority of FTC and can and will be challenged in courts in mandating ambiguous and improper technical specification for products. It is one thing to advocate fair reporting. It is completely different matter to say to the industry you have to do X and Y.

 

[Mnyb]

It’s e that I find confusing. The intent seems clear. If after pre conditioning, you can throw any arbitrarily selected frequency at it for 5 minutes at full power and it maintains less than 1% THD+n, your good. It needs to be able to do this for any frequency between 20 and 20k. Where I get confused is devising a reasonable test regime that I can be pretty certain the amp will then be able to pass that bar, as I obviously can’t test all the frequencies. What is the fewest number of frequencies and which ones can I test and be reasonably sure any frequency will then work?

Most problems seems to be at the extremes so the tests must include the ends of the range 20Hz and 20kHz or that 17k and 19k ?? ( keep forgetting the exact numbers sorry ) IM tests amir sometimes do ? realistically the distortion products over >10kHz is less important ( but not unimportant ) as the harmonics fall outside the audible range ie you wont hear them , could possible cause other problems if they are very high or be a proxy of some other issues .

 

[Old_School_Brad]

What you highlighted was for preservation of the old, amplifier rules. NOT new, 2024 regulations. I know because I have read many of the comments. Folks were galvanized to write the FTC and say it should not abandoned the effort. Here is one of many such comments:

"Please hold manufacturers true to their claims when selling equipment to the consumer. It is deceptive to advertise that a product capabilities which are truly lower than said products can actually measure up to. Consumers spend a lot of their hard earned money and should be given what they (consumers) believe they are paying for and actually getting.
Thank you."

I am in violent agreement with this. We want proper and comparable data for consumers. The problem is, FTC staff with no technical knowledge, ran off with substantial changes in the new ruling, while naively thinking they were simplifying/making things better. There was no proper research done by anyone with any expertise as to usefulness of 5 minute max power test at full bandwidth. Or even how to run such a test. This is the problem.

Reading through a ton of comments, I did not see a single one saying let's cook the amp for 5 minutes.

As I have said repeatedly, FTC should have delegated to a professional engineering organization such as AES to draft such standard and then just stamp them into law. FCC does that with SMPTE for television standards. And at any rate, has extremely rigorous process. FTC personnel are simply unqualified to create technical standards with such specificity.

I think this goes beyond the authority of FTC and can and will be challenged in courts in mandating ambiguous and improper technical specification for products. It is one thing to advocate fair reporting. It is completely different matter to say to the industry you have to do X and Y.

While I generally agree with you that the rules are not perfect, your argument leans heavily on "would've, could've, should've" scenarios.

The fact remains, the ruling is in place. If there’s no way to change it, the only option is to face it directly as is.

 

[amirm]

The fact remains, the ruling is in place. If there’s no way to change it, the only option is to face it directly as is.

The ruling can be challenged in court on the basis that it is not practical, can harm consumer interest by increasing cost of goods, and potentially goes beyond authority of FTC. Fortunately we don't have to go there as the chances of any enforcement action is as close to zero as possible.

What we are discussing is people putting pressure on me to adopt it and become FTC enforcer. I have explained that I will not do that. And given reasoning for it.

 

[Old_School_Brad]

That would be the analogy I might use with respect to running the FTC test!

Ha! That is funny, though it’s not quite the same things being addressed.

Whatever I do, needs to be proper and defensible. The first time I get challenged on it by a company, I need to be able to tell them how to replicate the issue. This is why I have state of the art, industry approved gear for testing today instead of hobby level stuff.

As for automation, I need it because I can't sit there and run such a test manually. It just takes too much time.
But yes, all this is extra work if we want to do it right. And I am not sure yet if it is worth my time.

I get it, I really do. But are you certain you need to make your data completely court-proof? Maybe it’s just a necessity in the U.S. to safeguard against potential "defamation" claims...

I've backed the FTC because I prioritize accurate and continuous power measurements. The origins of the rule or who started it don’t concern me at all.

 

[Sokel]

The ruling can be challenged in court on the basis that it is not practical, can harm consumer interest by increasing cost of goods, and potentially goes beyond authority of FTC. Fortunately we don't have to go there as the chances of any enforcement action is as close to zero as possible.

What we are discussing is people putting pressure on me to adopt it and become FTC enforcer. I have explained that I will not do that. And given reasoning for it.

That's totally up to you.
I wouldn't either with member's amps or the companies who don't care to rate them that way.

But what with the ones who will follow the rule and rate amps according to this?
Wouldn't be nice to have a way to cross-check their claims?

 

[Mnyb]

At least one of them seems to have done extended testing around full power to prove their thermal design:
https://www.audiosciencereview.com/...-ncore-amplifiers-overheat.49087/post-1758153

yes vera audio seems to master thermal management of these modules , it should be done this way or similar .

Btw I have no problem with amps that do 50w continues and 250w peak that are small and run cool ( or 10w amp with 100w peak ) . that would probably be well inside the crest factor of my music taste and work well in practice.

It would be overengineering if max, continues and peak power where the same, you may demand that of expensive high end amps if you have that kind of money .