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

Given this forum is all about the science of audio, and science is about metrics and specifications, I would suggest that real life, actual specifications should be pretty important personally.
 
I think it’s essential for promoting honesty in power ratings. Misleading claims like "peak" or "music power" have confused consumers for long, often highlighting inflated figures obtained by 20ms or below test signals, instead of meaningful ratings.

This rule sets standardized testing methods, ensuring all manufacturers measure performance figures consistently. Many reputable brands already follow the same or similar guidelines, and they have for decades, showing that compliance is achievable and not unreasonable. I've highlighted several examples of this in post #43.
Clear testing standards will help build trust among consumers, making it easier for everyone to understand product specifications.

I don't see why the FTC rule could be considered a burden; it protects consumers and encourages fair practices in the industry. It may in time even promote innovation.
 
But how will they know they've found an amp that can fullfill their needs if the power spec are unclear, that's the point of discussion I believe? It's not that Hifi amps than can deliver more than 50W continously don't exist. Looks like your best bet today is the size of the heatsinks and transformer instead of specs, altough with class D amps and SPS's it's more difficult to assess intuitively.
Pro people around audio probably can tell,my installers advised me about 1200as's as a 300W amps despite the brochures (their positive advice was more in line of reliability) .
Same at their datasheet and see how funny it is (I highlighted my use case as I use them in monos for my lows,under 250Hz)


before.PNG

Before

after.PNG

and after :facepalm:

Now,Amir measured a crippled implementation of them (a stereo one with an "audiophile" buffer on the front,the peachtree amp500) and it delivered 2x600 W at the knee.Is that the truth?
@StigErik tortured them too and it was interesting.
At my part I imagined that the sane thing to do is to calculate my needs was choosing by the 300W spec and anything above is welcome.
But one way or another I did had the data and it would be way nicer if I had them right from the start at their brochure.Time is money,spending it to discover the hidden specs is not nice.
 
Following this with interest. No axe to grind on the politics or philosophy of all this. Is FTC compliance necessary, I don't know.

Standards are great, they allow meaningful comparison of Amps and there is a comfort in knowing that a manufacturer has the confidence to demonstrate compliance. Tests here are standard, so they allow comparison with other Amps *tested on this site* and that's helpful - it's still difficult to make comparisons with Amps that are *not* tested here.
If specifications are quoted then they should be met, and there should be no ambiguity (is reported power 'continuous', peak or other ... should be clear).

My main take-away so far is the importance of thermal management and specifically the size/effectiveness of the heatsink.
I still can't see any way of understanding what sort of heatsink is in various amplifiers. Perhaps it's in service manuals somewhere (where those are available), perhaps a manufacturer would just tell me if I asked them (not going to do that until I'm ready to buy).
I can see a use for FTC compliance as a proxy for confirming good thermal management - if the Amp passes the continuous power test then is was capable of managing the heat...

Not asking to be spoon fed and happy to do my own research, quite enjoying learning more about this stuff - really wish all Amps reported their specs in a consistent, comparable manner though. Seems to me that FTC compliance, apart from anything else, would help with that.
 
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In my "torture test" with 50 seconds of a real signal* (aka the "Interstellar black hole"), the ICEpower 1200AS/2 could deliver about 2x300W before thermal shutdown. The supposedly more powerful 2000AS/2 could actually deliver slightly less than 2x300W.

The test I performed is not purely academic to me, as it represents something that can and will happen if you use the amp to power large subwoofers. The crest factor of low frequency content is much lower than for a full-range signal, thus the continuous power can be quite high.

The crest factor of my test signal is as low as 3.9 dB.
 
My testing pushes the amplifiers well into clipping multiple times. This is precisely what happens during playback of music if the amp is pushed beyond its limit. That said, neither my testing or FTC requirements are reliability metrics/processes. I put myself to college repairing hundreds of amplifiers during the time FTC rules were in full effect. Whether something has an FTC spec does not mean at all that it is reliable.

To come up with any kind of reliability testing, you need to do far more homework than guessing here and there.
No. Your “pushing to the limits” is undefined (you never defined it exactly, you never shown the record of your test level sweep. And, speaking about what happens with music is again undefined and irrelevant, as we can find various very different samples of music with different crest factor and rms power over longer or shorter period of time. The main problem, to me, is that you call this forum scientific or reviews called scientific, which they are not. Definitions are vague and reasoning is based on opinions an emotions and not on facts and standards. If you clearly stated it is rather about business then I would be satisfied.
 
Following this with interest. No axe to grind on the politics or philosophy of all this. Is FTC compliance necessary, I don't know.

Standards are great, they allow meaningful comparison of Amps and there is a comfort in knowing that a manufacturer has the confidence to demonstrate compliance. Tests here are standard, so they allow comparison with other Amps *tested on this site* and that's helpful - it's still difficult to make comparisons with Amps that are *not* tested here.
If specifications are quoted then they should be met, and there should be no ambiguity (is reported power 'continuous', peak or other ... should be clear).

My main take-away so far is the importance of thermal management and specifically the size/effectiveness of the heatsink.
I still can't see any way of understanding what sort of heatsink is in various amplifiers. Perhaps it's in service manuals somewhere (where those are available), perhaps a manufacturer would just tell me if I asked them (not going to do that until I'm ready to buy).
I can see a use for FTC compliance as a proxy for confirming good thermal management - if the Amp passes the continuous power test then is was capable of managing the heat...

Not asking to be spoon fed and happy to do my own research, quite enjoying learning more about this stuff - really wish all Amps reported their specs in a consistent, comparable manner though. Seems to me that FTC compliance, apart from anything else, would help with that.
That's a great guide here:


About size,etc,some state the data:

thermal.PNG

(both are easy to find,and yes,they are big-ish)
 
In defense of ICEpower, they do state solid specs in publicly visible datasheets that "everone skilled in the art" can double-check and confirm (which I did). This is OEM stuff and works exactly as advertised, and it's the burden of the implementer to decide whether it's going to be sufficient for the use case or not.
 
Even giant heat sinks won't make the "2x2000W" ICEpower 2000AS/2 deliver more than 2x280W according to my own tests.
These class D amps with SMPS generally have issues at continuous very high power, due to economic overall design and thermal management including the SMPS used. The parts under thermal stress must lie directly on the heatsink with lowest thermal coefficient possible and enabling very good air circulation (fins, number of them, depth). Indirect transfer through Al base plate of modules does not work well.
 
In defense of ICEpower, they do state solid specs in publicly visible datasheets that "everone skilled in the art" can double-check and confirm (which I did). This is OEM stuff and works exactly as advertised, and it's the burden of the implementer to decide whether it's going to be sufficient for the use case or not.
You are absolutely right. I should have checked the datasheet before I ordered my modules....

But they do market them as 2x2000W amps perfect for subwoofers. They are NOT.

1733399375819.png
 
These class D amps with SMPS generally have issues at continuous very high power, due to economic overall design and thermal management including the SMPS used. The parts under thermal stress must lie directly on the heatsink with lowest thermal coefficient possible and enabling very good air circulation (fins, number of them, depth). Indirect transfer through Al base plate of modules does not work well.
It must be said that testing the adequacy of the finished product heat dissipation system for every real world scenario requires extremely complex tests for an OEM. I don't even know if there is a standard in that.
I believe, however, that once the module manufacturer accurately specifies the losses in watts according to the load / power delivered, sizing the heatsink correctly is easy (but producer must ensure that the heat is properly transferred from the sources to the exchange point).
The problem is that most of the time sizing it for the worst case means making a tank. And if the worst case occurs in 1% of cases, perhaps it is not necessary.
However, correctly mapping uses and determining the most representative case is the key to everything. Some OEM skimp on this in my opinion and rely on the high variability of use cases.
 
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Some of us feel the need of honest specifications of amplifier output power according to acknowledged documents like FTC regulations and IEC standards. The reason is to get comparable data, protect potential customers and draw attention to false claims of some manufacturers.

I have decided to make such tests myself ad so far I have tested several well known amplifier and also one of my DIY designs. The links to the tests and results can be found below:





Thanks @pma for this work and sharing it with us.
 
But they do market them as 2x2000W amps perfect for subwoofers. They are NOT.
That’s what this thread is about. Such marketing easily fools common consumers and they buy the product in a good faith, as they are unable to discover the caveats.
 
It is an abandoned law. No enforcement. No one cares about it. I think I have only seen one product that had a mention of FTC. Years ago, there were always footnotes about FTC power specs if not in the specs themselves. This hasn't been the case for years now.

Are you asleep at the wheel? Seriously? :facepalm:
 
It's really simple.

Let's just start reporting each and every product ASR reviews (or any other remotely competent reviewer/tester) that DOES NOT reach its advertised, compliant power output to the FTC.

Abandoned law my #ss.

Start testing power amplifiers properly or pack up the AP.
 
But they do market them as 2x2000W amps perfect for subwoofers. They are NOT.
Like anywhere else, there is marketing in order to compete and get noticed. I can tell you from personal contact with ICEpower engineers that they were not really happy about this marketing, again like anywhere else ;-)

Even giant heat sinks won't make the "2x2000W" ICEpower 2000AS/2 deliver more than 2x280W according to my own tests.
Still about 2x of what the datasheet says, 2x135W.

These and other ICEpower modules are extensively and successfully used in large active studio monitors when the large short-term power headroom is required to faithfully reproduce uncompressed raw signals and the long-term power is still enough to impress the band in the control room big time ;-)

If you want maximum continuous power from them you need to design proper forced-air cooling, blowing directly over the PCB as well as through a finned heatsink tunnel the module is mounted on. Notably with 110V mains the module itself dissipates almost half the amount of power it delivers to the load, that heat has to go somewhere, quickly....
 
Pro people around audio probably can tell,

I was asking for a friend ;) Meaning, I'm one of those pro's and all the amps we use run at max rated power for at least 24 hours non stop, driving low impedance loads, clipping leds flashing constantly, even when stacking 8 of them on top of each other. So for me it has always been a big contrast with Hifi spec's, where rated power is very often meaningless.
 
Back to the 5 minute sine test at rated power - my A250W DIY amplifier, rated at 2x250W/4ohm, which I call higher mid power amplifier, passed the 5 minute 2x250W/4ohm/1kHz/THD+N<1% easily and would continue to give this power. One may say I am biased, but OK, I believe that Accuphase amplifiers would fulfil their rated power specs. Someone bring me one here ;).

Let's just start reporting each and every product ASR reviews (or any other remotely competent reviewer/tester) that DOES NOT reach its advertised, compliant power output to the FTC.

Toping B100

AIYIMA A07 with 50V power supply (little less than 48V in fact), the claimed power is 250W (and with sine test 100W/4ohm/1kHz, one channel driven, the amplifier shut down after 1 minute).

P.S.: I should be testing SMSL A100 soon. The small problem is I have to buy units under test first.
 
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