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

[DonH56]

That can't be the goal Don. The clear aim of the government is performance specification, not reliability testing.

Any half decent thermal analysis should be with low frequency signals into 3 to 4 ohm load, not 8 ohm. Testing needs to take into account real statistical profile of music. Not pure sine wave to 20 kHz. I can see in 1974 sine wave was the only thing we had. But today, that makes no sense. This is why M-Noise has had legs and has gotten approval from AES: https://meyersound.com/news/aes75/

"In the work of the AES SC-04-03-A Task Group, AES75 details a procedure for measuring maximum linear sound levels of a loudspeaker system or individual driver using the M-Noise test signal. Mathematically derived from analysis of hundreds of music selections spanning all genres, M-Noise uniquely exhibits a crest factor characteristic of music program signals. "

Many amplifiers also never see the need to drive 20 Hz as speakers people use don't go that low. As such, there should have been a secondary class of say, 40 Hz and above.

We should always, always try to have industry regulation before we give up and have government mandates. This is indeed how things normally work. Government threatens regulation (usually Congress) and the industry takes notice and attempts at regulation for self-governance. In this case, I am sure we could have done far better than this one liner from FTC. If that fails, then we can revert back to government mandate but with far more thought than this ad-hoc process.

It's not reliability testing, it is an indicator. Good thermal management is important for electronic component lifetime and you need that to pass the FTC requirement (among other things).

Industry going wild with power ratings is how we ended up with the FTC rule to begin with.

IIRC there were some comments about using other test signals. I think I suggested using colored noise (not necessarily pink) with appropriate crest factor, but sine-wave testing is simple to conduct and understand, and of course has history with both the government and manufacturers.

I have no desire to engage in endless debate on a topic clearly going nowhere, at ASR or the FTC. Too many other things going on in life for this.

 

[mhardy6647]

also of note, vis-a-vis "FTC '74", manufacturers large and small met the requirements for several decades with products inexpensive and expensive, across several orders of magnitude of power outputs.


(ahem -- not spec'd both channels driven -- but, at least, honest )


(some cheap Sansuis)


(a trio of cheap "15xx series" marantz receivers -- lacking even Gyro-touch tuning. )










The specification winner of the 1970s Receiver wars.

source: https://www.hifiengine.com/manual_library/pioneer/sx-1980.shtml


The runner-up

 

[Sokel]

Raise your hand if you want me to report Denon's AVR that does everything excellently, yet their power rating doesn't comply with FTC.

I would never report anything to anyone,is completely out of my character,even these big companies who does not differ from power (economic and political) schemes sometimes.
I prefer self-regulation and honesty.
I have no doubt that the rule will not aplly.But I like to dream of excellent engineering allover and not to certain aspects,and yes,no matter the extra cost.
I prefer to cut other edges but not what is meaningful and at a power amp is first electrical safety (regs,certs and stuff) and then power for every scenario I may need it.
I do not represent the usual user,I know.I only speak for myself.

 

[kyuu]

also of note, vis-a-vis "FTC '74", manufacturers large and small met the requirements for several decades with products inexpensive and expensive, across several orders of magnitude of power outputs.

Do we know for a fact that all of those passed FTC testing? What were the requirements back in '74? A good many of those devices specify frequency ranges that aren't the full 20-20000 Hz.

 

[mhardy6647]

Do we know for a fact that all of those passed FTC testing? What were the requirements back in '74? A good many of those devices specify frequency ranges that aren't the full 20-20000 Hz.

The spec required that the range be stated, not that it be 20-20k. That one channel driven example is interesting, as I am not sure that was FTC '74-compliant.

Did they all pass? I am pretty sure that the mfgr. of every model on the market managed to supply at least one example to a lab for testing that passed and that the required paperwork was filed.
Would every individual component pass? Probably not, but maybe. Depends on the internal QC requirements of the mfgr, I would think.
It is instructive to read Audio, High Fidelity, and Stereo Review tests from the era (all available at www.worldradiohistory.com, by the way). Most passed. Many passed without breaking a sweat. Some didn't pass at all.
See, e.g., https://www.audiosciencereview.com/...-the-amplifier-rule.20303/page-9#post-2149290 where I picked a few (very unscientifically).

source: https://www.worldradiohistory.com/A...iFI-Stereo/70s/HiFi-Stereo-Review-1979-04.pdf pg 64 (Phase Linear 700 Series Two (!?!) review)
The 700 Series Two technically passed, but would get a "bullet" (asterisk) in my list.



So... how important is power (per @Amir's, and some others', countermelody in this little thread-fugue )? Not particularly, really, but it's straightforward to measure and has been a high-visibility number (like horsepower for an automobile) for a long, long time. Like horsepower (e.g., in the US in the 1960s), the numbers game around power ratings has periodically been seriously abused by marketing forces.

The FTC's continuous power spec asks a lot of an amplifier -- if nothing else, adequate heatsinking and a very capable power supply. I'd posit that an amp that can deliver under FTC conditions can be expected to have a long and useful life (which is not to say that bad, random things don't happen). The current cheap, disposable amplifier mentality is irresponsible from perspectives of human resources (the labor who's building the stuff, probably under less than ideal working conditions) and environmental sustainability (the modules are, by and large, effectively irreparable). I think it's, at the least, very unfortunate that the notion of high value has been trumped (that's a lower case t ) by low cost.

For me, and FWIW, the worst thing about most of the power testing schemes (and my major beef with the issue, other than outright misrepresentation of instantaneous power capability as a reasonable "power rating") is measuring performance into a resistive load. This is a far bigger gap in the real world (especially considering the impedance and phase curves of so-many modern loudspeakers) than continuous watts vs. music power or what have you.

Mind you, my daily driver amp is capable of something like 3.5 watts continuous per channel into (in my case) 16 ohms at probably 5 to 10% THD, and somewhat bandwidth-limited at both ends by the performance of its OPTs (and my ability to fund same without selling a kidney ). It is, however, gloriously fit for purpose.

 

[Old_School_Brad]

Hi all, below is a draft of my test/review of SMSL A100 with respect to rated power as well

SMSL A100 amplifier test review

Comments are welcome, I may then consider to post it at ASR.

That's highly valuable information.
It can be the best amplifier in the world, but ifnit disturbs the environment it's a deal breaker.

 

[Old_School_Brad]

The spec required that the range be stated, not that it be 20-20k. That one channel driven example is interesting, as I am not sure that was FTC '74-compliant.

Did they all pass? I am pretty sure that the mfgr. of every model on the market managed to supply at least one example to a lab for testing that passed and that the required paperwork was filed.
Would every individual component pass? Probably not, but maybe. Depends on the internal QC requirements of the mfgr, I would think.
It is instructive to read Audio, High Fidelity, and Stereo Review tests from the era (all available at www.worldradiohistory.com, by the way). Most passed. Many passed without breaking a sweat. Some didn't pass at all.
See, e.g., https://www.audiosciencereview.com/...-the-amplifier-rule.20303/page-9#post-2149290 where I picked a few (very unscientifically).

View attachment 411958



source: https://www.worldradiohistory.com/A...iFI-Stereo/70s/HiFi-Stereo-Review-1979-04.pdf pg 64 (Phase Linear 700 Series Two (!?!) review)
The 700 Series Two technically passed, but would get a "bullet" (asterisk) in my list.



So... how important is power (per @Amir's, and some others', countermelody in this little thread-fugue )? Not particularly, really, but it's straightforward to measure and has been a high-visibility number (like horsepower for an automobile) for a long, long time. Like horsepower (e.g., in the US in the 1960s), the numbers game around power ratings has periodically been seriously abused by marketing forces.

The FTC's continuous power spec asks a lot of an amplifier -- if nothing else, adequate heatsinking and a very capable power supply. I'd posit that an amp that can deliver under FTC conditions can be expected to have a long and useful life (which is not to say that bad, random things don't happen). The current cheap, disposable amplifier mentality is irresponsible from perspectives of human resources (the labor who's building the stuff, probably under less than ideal working conditions) and environmental sustainability (the modules are, by and large, effectively irreparable). I think it's, at the least, very unfortunate that the notion of high value has been trumped (that's a lower case t ) by low cost.

For me, and FWIW, the worst thing about most of the power testing schemes (and my major beef with the issue, other than outright misrepresentation of instantaneous power capability as a reasonable "power rating") is measuring performance into a resistive load. This is a far bigger gap in the real world (especially considering the impedance and phase curves of so-many modern loudspeakers) than continuous watts vs. music power or what have you.

Mind you, my daily driver amp is capable of something like 3.5 watts continuous per channel into (in my case) 16 ohms at probably 5 to 10% THD, and somewhat bandwidth-limited at both ends by the performance of its OPTs (and my ability to fund same without selling a kidney ). It is, however, gloriously fit for purpose.

This is why I find the pushback and criticism of the rule puzzling. Manufacturers have been adhering to it since the 1970s (that’s half a century ago for those who recall it vividly ), across all product categories -entry-level, mid-range, and high-end. This demonstrates clearly that it’s not an issue when you follow good design practices and apply fundamental principles from physics and electrical engineering.

The idea that it’s overly costly, harmful to businesses, or an unfair demand doesn’t hold up under scrutiny.

 

[restorer-john]

The idea that it’s overly costly, harmful to businesses, or an unfair demand doesn’t hold up under scrutiny.

You'd expect those sorts of BS arguments to be made by people with vested interests in cutting corners, costs and increasing profitability to make bigger returns to investors or shareholders and certainly not coming from independent reviewers with interests in quality.

 

[ssn22]

If you want to get closer to science
Then you should stay away from business and capital...
The reverse is also true.

 

[amirm]

This is why I find the pushback and criticism of the rule puzzling. Manufacturers have been adhering to it since the 1970s (that’s half a century ago for those who recall it vividly ), across all product categories -entry-level, mid-range, and high-end.

No. They abandoned the practice long time ago. I always look for specs for products I review. I can count on one hand the time of times I have seen FTC mention in power rating.

Keep in mind that in the original era, audio equipment was profitable and people routinely paid by the pound. You could double the heat sink and sell at higher price. Today, folks are trying to stuff 12 channels of audio in one box. They have not only shrunk the size of heatsinks, but given up on extrusion and use spring steel. To get around UL excess heat rating, they talk the customer into setting the unit to "4 ohm" and then sharply reduce power when set so!

But, and this is key, consumers are going along with it. No new problem has been created as to need FTC intervention at even stronger level. Car amps? Sure. It is crazy there but people know that for the most part.

This demonstrates clearly that it’s not an issue when you follow good design practices and apply fundamental principles from physics and electrical engineering.

Yeh, and extra cost. The market is available to anyone to overbuild amps today. If you don't see it is because there is just not demand for it. Folks are fine with good enough and bargain prices for amplification.

My own amps are 120 pounds each and cost $25,000. They are massively overbuilt with most of that weight going to heatsinks. If i were to buy them again, I would get a Hypex amp at 10% the weight and less than 5% the cost. I don't want 30 pounds of heatsinks on them, nor do I want a noisy fan just to pass FTC regulations. Something goes wrong with it, I can swap out modules. I don't know what to do with the heavy monsters I have now -- both of which have broken down.

Net, net, there is no free lunch. Broad regulations will have unintended consequences. Don't think you are getting something for nothing.

 

[amirm]

BTW one cheat would be to have a simple timer for the amp running at full power continuously and turn on a cheap fan. For normal music, it would never come on. But for FTC testing, it would and drastically cool down the unit for the 5 minute interval. You get nothing better but pay a bit more for the cost of the fan.

 

[amirm]

You'd expect those sorts of BS arguments to be made by people with vested interests in cutting corners, costs and increasing profitability to make bigger returns to investors or shareholders and certainly not coming from independent reviewers with interests in quality.

I can tell crap made audio products from a mile away. A 5 minute FTC test is meaningless in that regard. You sound like someone is certifying a product comprehensively instead of a one time test.

 

[pma]

You have two opposite design approaches - 80 kg Krell vs. Topping B100 undersized amp good just for 5W SINAD measurements. Both are wrong. You may fulfil FTC requirements with a rational, 19” 2U or 3U case design and 10 - 15 kg weight, no fan needed. Each to his own, but advertising based on false numbers should be banned.

 

[mhardy6647]

You'd expect those sorts of BS arguments to be made by people with vested interests in cutting corners, costs and increasing profitability to make bigger returns to investors or shareholders and certainly not coming from independent reviewers with interests in quality.

...but advertising based on false numbers should be banned.

Yeah, huh?
That was, indeed, the catalyst for the original "FTC '74" regulations.

 

[RickS]

You have two opposite design approaches - 80 kg Krell vs. Topping B100 undersized amp good just for 5W SINAD measurements. Both are wrong. You may fulfil FTC requirements with a rational, 19” 2U or 3U case design and 10 - 15 kg weight, no fan needed. Each to his own, but advertising based on false numbers should be banned.

While you are a better judge of design validity than I, suggest you just stated the OP problem concisely "advertising based on false numbers should be banned". The ongoing debate is whether the new FTC regulation is an effective way to reduce false advertising regarding amplifier power. Even if it is a reasonable proxy, the next question is how does get effectively implemented? As with Amir, I have doubts about the regulation's effectiveness for doing more to help the consumer.

Even if Amir did test some amps, we know he would not be even testing even a majority of them. The same applies to you to an even greater degree. Amir is arguing that his existing tests already show when amp power may not be as advertised. He also mentions that the FTC is unlikely to be able to stop the offending company. We all can see evidence of this as politics and the courts get involved with technology issues.

As Amir proposed (much) earlier, can we step back and focus on what more might be done to avoid false advertising? It seems to me that the goal of your OP has gone beyond your intent. More than 270 posts later, do you still feel FTC regulation is an effective approach to prevent false advertising?

 

[SIY]

Interestingly, amidst the angst and wailing about heatsinking and large sustained sine waves, there's only a few mentions of two other highly unrealistic parts of the FTC regulations- load and test signal. That's where I see the biggest problems, and there's no simple answer, unfortunately.

 

[mhardy6647]

Interestingly, amidst the angst and wailing about heatsinking and large sustained sine waves, there's only a few mentions of two other highly unrealistic parts of the FTC regulations- load and test signal. That's where I see the biggest problems, and there's no simple answer, unfortunately.

The test signal (sine waves), to my way of thinking, goes hand-in-hand with the Gestalt of the test (for better or worse). Maybe white noise'd be good?
I mean, they could pick a piece of reference music, I guess -- maybe The Planets. Maybe Jazz at the Pawn Shop.

ahem.

The load -- yeah... that's the one that bugs me (as I mentioned above). Maybe a synthetic Infinity IRS-Beta. That'll separate the wheat from the chaff!

 

[mhardy6647]

Sorry, I just had an hallucination a thought.
I can imagine a testing lab if Jazz at the Pawn Shop were chosen as the test signal.

Hey, Al -- the amplifier passed the test, but then it vomited. Is that OK?

 

[SIY]

Maybe a synthetic Infinity IRS-Beta.

One could argue that this isn't representative of the vast majority of use-cases, thus increasing unnecessarily the cost to consumers. If someone is selling into that niche market, there's nothing to stop them from showing how much better their product is for pathological loads as well as a basic FTC compliance.

 

[mhardy6647]

One could argue that this isn't representative of the vast majority of use-cases, thus increasing unnecessarily the cost to consumers. If someone is selling into that niche market, there's nothing to stop them from showing how much better their product is for pathological loads as well as a basic FTC compliance.

Do you really think that the average passive loudspeaker of 2024 is much "better" in terms of amplifier-friendliness?
There seem to me (strictly anecdotally) to be plenty of sadistic impedance and/or phase curves out there.

Random example(s). My assay was very simple (and this is true). I clicked on speaker reviews at "Stereophile.com" and picked a few that looked like most modern floorstanders to me. This was my first pick. $5k USD the pair (i.e., moderate, again, by modern standards).

SVS Ultra Evolution Pinnacle loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

Tekton $30k the pair. Oh the humanity.

Tekton Moab Be loudspeaker Measurements

Sidebar 4: Measurements

www.stereophile.com

Wilson Sasha -- leveraging an old Car Talk joke? (Sasha Goode-Speaker) $48,900 the pair ("Yes, you even get some change back from your $50k bill!")

Wilson Audio Specialties Sasha V loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

Does the world really, really need loudspeakers with 2-ohm impedance in the range of 70 to 120 Hz? I mean, fortunately, there's not much signal there in real music.
EDIT:
Ahem. In (some) seriousness, @SIY, what would you select as an average passive loudspeaker? Not puttin' you on the spot -- just curious? Should we weight by sales numbers (i.e., market penetration)? So, maybe, some KEF product?