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

[Multicore]

Not according to the standard - for amplifiers the standard REQUIRES a rating to be shown that does meet the standard. Although for active speakers, the standard probably doesn't apply.

Here we see a list of active speakers headlined with woofer diameter and watts. I'd like there to be some accountability there and the success of the thermal design ought to come into it. I don't know what that test should be. PA subs are a bit different from our situation here but I think it's related and illustrates a point.

https://www.sweetwater.com/c447--PA_Subwoofers

 

[Sokel]

IMO this is what some of the small amps by Topping, SMSL,Fosi etc.. will probably do. It's the simplest if they even bother to do anything or just have a wait and see attitude.

Opting out will (rightfully) cause the same jokes we tell about the companies who are afraid to send gear for measurements and an immediate suspicion about "how much weaker?"

 

[Old_School_Brad]

At this point, am just thankful for a responsive effort to get power back amid lake effect snowstorm here. Just before 6 last night, we heard a large crack and lost power. Seeing the house power line swaying, knew that something had hit the lines that run across the back of our property. We huddled in our home office for a few hours until the UPSes ran dry and then went to bed. I reported the outage and our local power company was on it and reported a estimated repair around 8:30. As they normally underpromise, was relieved. 8:30 came and went with no sign of a work crew. Around 10 pm, 2 large service trucks show up in front of our house. They look at the pole (it has a transformer on it) and get back in the truck and I get a notice repromising to 12:30.

While my wife manages to sleep, I cannot. The house temp has now dropped to 62F and I am wearing my winter coat and cap. It is about 20F outside and the snow subsides. The work started around 10:30 and close to midnight the trucks left. Still had no power and was really starting to worry. Went to tell my wife and the power returned.

Am very grateful we did not have to take action to prevent pipes from freezing and find somewhere else to take shelter! Nothing like a major house threat to remind you what is truly important.

That’s not too cold. Just remember to keep the water running. Flowing water disrupts ice formation and can stay in a liquid state even below freezing for hours or days, depending on factors like pipe friction, flow rate, and ambient temperature.
The most off-topic comment of the day...

 

[Geert]

I am game developing an automated and realistic stress test. We need to define it and someone needs to build it.

I think most people understand you can't take the risk of damaging loaned out equipment, so maybe a more carefull approach could already provide valuable insights. Most audiophiles understand an amp needs to have headroom to reproduce music with high fidelity, so people who are after sound quality won't drive Hifi amps at full power for extended periods of time. If you start from that assumption, you could test an amp at for example a third or half of the rated power (or half of available power according to your own power versus versus distortion measurement) and after 5 minutes start evaluating how temperature evolves. At what temperature does it settle? Does is settle or does it keep rising? Are certain components close to overheating? If so, reduce power or exit the test to avoid damage. You've already been doing a thermal measurement for a while. It's just a matter of doing it according to a specified protocol which includes well defined sustained higher power levels. Not a perfect test, but probably good enough for most Hifi lovers.

 

[mhardy6647]

Agreed. The question is whether some were really even "fit for purpose" tho. A few appear not to be imho.

May I just say (realizing full well this should be blindingly obvious to all on a forum like this) that the issue of what is a meaningful way to assess amplifier capability (to wit, amplifier output power) has been a conversation topic/flashpoint (!) for hifi audio practicioners for as long as the industry/discipline has existed?

Music ain't sine waves, one camp will intone. Well, I mean, it is and it isn't, right?
... and most loudspeakers (some planars notwithstanding) aren't pure resistive loads!

Yes, yes -- but steady state testing into a defined load with a defined signal makes for optimium reproducibility worldwide, the other camp would posit.

Yup.

 

[mhardy6647]

Patience. This type of failure comes suddenly, and only once.

 

[DonH56]

So we have @amirm and others arguing the spec is outdated, not representative of real-world signals, and thus not useful. Others like myself argue it is useful as a metric of reliability and thermal management for long-term use. Obviously for ASR testing Amir rules (and he has the constraint of not wanting to blow up customers' amps!), and others like @pma and Stereophile provide data, so at least there are FTC-compliant measurements out there for those wishing it.

I will note that the metric is power so 4 vs. 8 ohms is less relevant as long as tests are are rated power. Using a resistive load, like presenting performance in a single number like SINAD, provides a limited baseline that is only a starting point in understanding the overall performance, but to me and others it is a useful way to compare among amplifiers. A baseline starting point if you will. A similar argument can be made for reliability: a five-minute test is no guarantee of long-term reliability, actual reliability test are much longer and more complex, but if the amp cannot meet spec for five minutes you know where it stands. Basic tests are about as far as an average consumer can be expected to process assuming no engineering background (and even engineers specialize, nobody knows it all).

Whatever, clearly time for old farts like me to fade into the background.

 

[JustJones]

Opting out will (rightfully) cause the same jokes we tell about the companies who are afraid to send gear for measurements and an immediate suspicion about "how much weaker?"

Probably, but I don't see anyone looking at the cheap boxes that are under $200 caring that much because what's their alternative? If they were looking to spend $1000 and up then yes but for This ? I don't see anyone giving a crap that a $90 amp has “This rating was not tested under FTC standards.” in the manual.

 

[RickS]

@amirm stated in post #94 "It is an abandoned law. No enforcement. No one cares about it". The 2025 gov't. playbook seems to galvanize that in its' FTC section where it states its' intentions clearly (bold is mine):


That said, I've got huge respect for guys like @pma and @restorer-john for the fire in their belly for a scientific and ethical cause that they believe in. Any reporting of nonconformity will likely validate Amir's claim, if the incoming administration carries out the intentions laid out in FTC 2025.

I'll second your comments! Am not sure how long it takes for Amir's current round of amp tests but appreciate what he has done here. Anyone who is willing to extend his efforts (thanks Pavel!), is a bonus imo.

Along with being pragmatic about any FTC enforcement, I experienced the more stringent aspect of regulation in the industrial automation market. My employer had major resources to deal with regulations/standards (and added some as well). It was a major expense and eventually became so burdensome, some had to be contracted out. There were more expenses to also pay for external certifying agencies. In that space. you would find a full page of compliance specs and much was self-certifying. This compliance work also delayed time to market significantly. Am not saying that some of it was not worthwhile (notably safety aspects) but was not done due to concerns over federal government oversight.

Anyone who thinks that the US government is going to enforce FTC amplifier power specs is simply unrealistic with regards to what has transpired over the last few decades. For that matter, as has been pointed out, the better manufacturers will comply. Just because others will not, does not mean we should push an FTC compliance test effort on Amir.

 

[RickS]

That’s not too cold. Just remember to keep the water running. Flowing water disrupts ice formation and can stay in a liquid state even below freezing for hours or days, depending on factors like pipe friction, flow rate, and ambient temperature.
The most off-topic comment of the day...

Please excuse my (admittedly OT) post as I thought this thread could use some levity!

Yes, 62F is not too cold. My concern was if we had to take shelter elsewhere while sub-zero temps continued in a house without heat. As I shivered last night (low tolerance for cold), I was kept warm by knowing my government had updated regulations for audio amplifier power.

 

[pma]

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.

 

[Geert]

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 a serious electromagnetic interference issue. If I was a potential buyer, I would be very happy with this warning.

 

[amirm]

Anyone testing/reviewing and publishing power output results should be careful, very careful, to document the specifics of their testing regime and how it can, or cannot be interpreted to be in accordance with, or not, with FTC requirements. Otherwise, reviewers not covering their respective asses can be expected to be reported to the FTC for potentially misleading and deceptive conduct themselves...

Say what? There is no obligation on "reviewers" to do anything with respect to this FTC rule. We have freedom of press and no one is going to jam how a reviewer conducts any test, in audio or otherwise. Here is the FTC itself:

"The final rule requires uniform test conditions for amplifiers if sellers make certain claims about power output..."

The only obligation is sellers of amplifiers, not anyone else.

In your zeal to get back to good old days, you have really lost your way here John.

 

[amirm]

Can the implementation be better than the chip itself? No! And this is what says the datasheet.

They are compliant with that spec. SMSL says nothing about "continuous power." It has simple power rating of 80 watts at 4 ohm which is the same thing Infenion is spec'ing at 10% THD. Again, these companies are getting their numbers from major chip companies.

 

[amirm]

This part of rule making documentation cracks me up:

"Accordingly, the Rule standardized the measurement and disclosure ofsome, but not all, performance characteristics of power amplification equipment to“assure that . . . performance characteristics are based upon conditions of normal use by the consumer, i.e., conditions which are encountered in the home.”3"

The footnote 3 clearly states this goal is not met with this rule:

"3 Id. at 15392. Merely testing amplifiers under identical test conditions will not produce useful consumer information if the test conditions differ significantly from normal use conditions"

I can imagine a company taking FTC to court, then playing a sine wave from 20 to 20 kHz and asking how this is "conditions of normal consumer." I would actually play it for the full 5 minutes and see if there is anyone left with hearing ability!

The fact that the document itself attests to this fact should open and shut the case. We wouldn't even have to get into the fact that a dummy load is not a speaker.

I would think CTA would take such action if any enforcement comes toward any big member of their association.

 

[mhardy6647]

The complain is about the stated rated power.Lowering their numbers for continuous will change nothing,it will be the same cheap amp.

Egg-zack-a-tackly.

 

[amirm]

So we have @amirm and others arguing the spec is outdated, not representative of real-world signals, and thus not useful. Others like myself argue it is useful as a metric of reliability and thermal management for long-term use.

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.

 

[Sokel]

This part of rule making documentation cracks me up:

"Accordingly, the Rule standardized the measurement and disclosure ofsome, but not all, performance characteristics of power amplification equipment to“assure that . . . performance characteristics are based upon conditions of normal use by the consumer, i.e., conditions which are encountered in the home.”3"

The footnote 3 clearly states this goal is not met with this rule:

"3 Id. at 15392. Merely testing amplifiers under identical test conditions will not produce useful consumer information if the test conditions differ significantly from normal use conditions"

I can imagine a company taking FTC to court, then playing a sine wave from 20 to 20 kHz and asking how this is "conditions of normal consumer." I would actually play it for the full 5 minutes and see if there is anyone left with hearing ability!

The fact that the document itself attests to this fact should open and shut the case. We wouldn't even have to get into the fact that a dummy load is not a speaker.

I would think CTA would take such action if any enforcement comes toward any big member of their association.

They stated that a long period of time was consumed by negotiating with all that participate in the game and everyone was free to suggest,comment,etc.
It seems to me that a few bothered to do so.It would be different otherwise.

Some got lazy maybe?Who to blame?

 

[amirm]

Another truth is that this test is hard to fake or game or take advantage of stuff like we do in DACs for example (5V outputs for AP,etc) .

Oh, it is very easy to game as the government did not specify how THD is measured. If the bandwidth of the analyzer is set to 20 kHz, no harmonics of anything above 10 kHz is captured! So you could have 100% distortion at 11 kHz and above and would not matter! Hypex measurements reflect this for example:

See how the level of distortion is going down above 2 kHz? That is because of limited measurement bandwidth. I use 45 kHz bandwidth so still include some but not all the harmonics of high frequencies.

I also don't see anything about airflow in the draft spec, only an ambient temp of 77 degrees. I could have a fan near the device and help with convection cooling of the amp.

Then there is the spec for the load. How accurate must the "8 ohm" be? For high power amps, dummy loads heat up and change impedance.

 

[amirm]

Some got lazy maybe?Who to blame?

As I have stated repeatedly, I think it is a useless toothless regulation. So didn't care to get involved.

Ironically, if there is one entity that could put substantial weight behind this thing happening would be ASR! I have the tools, resources and knowledge to clearly show violations. 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.