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

[restorer-john]

Compliance with FTC rule is not free. Let's say the amp can only run for 1 minute at the stated power level instead of 5. To make it compliant, you would either need a fan, a larger heatsink or both. The former has a major disadvantage in noise and reliability as the fan fails. The latter increases cost (both in material and shipping). Are you willing to have every amplifier's cost be increased this way?

Also keep in mind that any fluff spec is identified in measurements I do. So people here are not being sold junk specs.

Compliance with the FTC rule is not optional either. It is law in the US.

I guess it comes down to how you value your credibility at the end of the day doesn't it?

You are rightly gaining presence on the internet as a source of useful test data and commentary for many classes of audio equipment. Do you want to continue to be the guy who takes over-specified amplifier boxes from low cost manufacturers, claiming power outputs they cannot achieve and then awarding them top marks for what is effectively a stepped burst sequence of indeterminate length and level?

Surely you can create a simple test sequence on the AP- 1/8th power for 1 hour followed by a 5 minute full manufacturer rated power test with a pass/fail. You go off, make a coffee, weed your garden, pick some seasonal vegetables and come back to either a lab full of smoke, or a nice "Passed" on the screen.

 

[antcollinet]

and come back to either a lab full of smoke .....

I can see how this potential is a problem though - for cases where Amir is testing gear sent in by members. If he states that the amp might be sent back destroyed and disclaims responsibility for that (as he must), we are going to get far fewer member amps sent in for testing.

I'd agree though for amps sent in by manufacturers. These should be fair game.

 

[ShadowFiend]

Then just put a big disclaimer on top of the review that "The test was done with a stepped burst sequence of 20ms, not continuous level signal. So viewer should be aware that this power can be insufficient to drive many speakers at relatively high volume".

 

[Old_School_Brad]

Then just put a big disclaimer on top of the review that "The test was done with a stepped burst sequence of 20ms, not continuous level signal. So viewer should be aware that this power can be insufficient to drive many speakers at relatively high volume".

That would also align with the overarching guidelines of the FTC rule. The manufacturer would still be required to include the test values in their specifications in compliance with FTC regulations.

 

[wwenze]

I can see how this potential is a problem though - for cases where Amir is testing gear sent in by members. If he states that the amp might be sent back destroyed and disclaims responsibility for that (as he must), we are going to get far fewer member amps sent in for testing.

I'd agree though for amps sent in by manufacturers. These should be fair game.

Power supplies are subjected to overload, over current (short circuit) and hipot tests so manufacturer samples are certainly fair game. If I wanted to buy something with no protection I'd buy it from a white van.

 

[pma]

for cases where Amir is testing gear sent in by members.

Not by members. Many amplifiers are sent by manufacturers for the advertising reason. Like Topping and similar amps. There would be no reason why not to test e.g. Topping B100 honestly, not only to make it a 5W SINAD breaker.

 

[antcollinet]

Not by members. Many amplifiers are sent by manufacturers for the advertising reason. Like Topping and similar amps. There would be no reason why not to test e.g. Topping B100 honestly, not only to make it a 5W SINAD breaker.

From the same post you quoted.

I'd agree though for amps sent in by manufacturers. These should be fair game.

 

[amirm]

It sometimes happens that an amplifier rated "Output Power 100W @4Ω THD+N<1%" dies within 3 seconds of pushing 33 watts into a 4 ohm load:
- https://www.audiosciencereview.com/...ping-b100-amplifier-review.57036/post-2149364

How do you know if the test conditions were a) as stated and b) repeatable?

 

[Deleted member 58670]

The dynamics and transients from the test track would be more challenging than a steady-state signal, right?

No. Delivering a lot of continuous power is far more demanding for the PSU and cooling of the amp.

 

[amirm]

If testing an amplifier for 5 minutes at rated power is too much, then perhaps testing it for at least 5 seconds would tell us more about an amplifier than just a few milliseconds, as it is currently done with "Power Versus Distortion" measurements.

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.

 

[Sokel]

The whole thing here is about thermals,lets be real.
And it's like we pretend that something has change over the few last years.
Nope,heat is still the good,old heat we know.

Some amps got more efficient (usually close to their high wattage) but that's it.
Driven a little bit harder they will have to dump a fair amount of heat somewhere.Or shut off.In any case a protection scheme (or multiple) has to be included,both about safety and protecting gear upwards.

 

[amirm]

And it shut down after a while at this power level 170W.

Tiny little amplifier selling for so little money and we are complaining that it couldn't produce 170 watts steady state long term???

 

[Sokel]

Tiny little amplifier selling for so little money and we are complaining that it couldn't produce 170 watts steady state long term???

No Amir,no one is complaining about that.
The complain is about the stated rated power.Lowering their numbers for continuous will change nothing,it will be the same cheap amp.

 

[amirm]

Compliance with the FTC rule is not optional either. It is law in the US.

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.

I just looked up Sony AVR specs. They don't even list the power level! "

• 7.2 CH A/V Receiver (8 ohms, 1 kHz, 2ch, THD 0.9%)"

And this is a $1,000 AVR!

 

[amirm]

No Amir,no one is complaining about that.

What was he saying then? Seemed like a clear complaint to me.

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

That spec comes from a major, multi-billion dollar company. Texas Instrument who makes that IC: https://www.ti.com/product/TPA3255

"TPA325

315-W stereo, 600-W mono, 18- to 53.5-V supply, analog input Class-D audio amplifier"​

Under some conditions, some way, the thing produces such power. My measurements show that both channels driven, it actually gets close if you allow SINAD of 30:

I mean why bring up examples like this and put the fault at the feet of companies like AIYIMA? It is absurd.

 

[amirm]

Folks, we have an open marketplace. If folks are willing to pay for amps that run for 5 minutes at whatever wattage, companies will make them for you. If you don't see them is because there is no problem to solve, nor a market for it.

 

[Geert]

Folks, we have an open marketplace. If folks are willing to pay for amps that run for 5 minutes at whatever wattage, companies will make them for you. If you don't see them is because there is no problem to solve, nor a market for it.

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.

 

[Deleted member 58670]

Folks, we have an open marketplace. If folks are willing to pay for amps that run for 5 minutes at whatever wattage, companies will make them for you. If you don't see them is because there is no problem to solve, nor a market for it.

That may be true. But I did get slightly aggravated when I realized that my "2x2000W" amp in fact entered protection and shut down at far less output power than that.

 

[Sokel]

That may be true. But I did get slightly aggravated when I realized that my "2x2000W" amp in fact entered protection and shut down at far less output power than that.

Yep,that's a real miss by icepower.
What's also outrageous is that they also give specs for 10% THD+N (even higher than 2x2000W) Not the only ones though,I see a lot of 10% going around,even in TI's papers.

 

[Davide]

I believe that in any technological market aimed at the end user the same problem of inconsistency of data occurs with respect to real use, to some degree.
If we stay in the audio, just think of the data typically provided for the speakers.
They are almost insignificant, however correct. And even when we have more in-depth and standardized data, there is still a margin of non-representativeness, as well as uncertainty, regarding the practical case.
So what should we do?
The general protection of individuals is the basis of society, and in the markets it takes place with regulations. Creating effective and sustainable regulations is the goal to aim for.
Where the regulations do not arrive (or doesn't make sense they arrive), sometimes independent tests such as ASR arrive.
I am also convinced that the 5-minute test is not representative of reliability. But it is of continuous power. And to me it is a relevant parameter to compare amplifiers, as well as distortion.
Of course one knows how to use that data for pairing with the speaker is another matter...
The fact that the need for such a test does not emerge from the market is also true. I think there are few who have chosen an amp that goes into protection in practical use. I think there are more those who find themselves with a failed amp for other much more complex reliability reasons, not detectable by easy tests.