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

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.
These claims lack substance. There is nothing forcing the manufacturer to alter their design. They simply need a new line stating "FTC-rated power," and they can include whatever derived test results they choose below that. It’s beyond me how this harms consumer interests.
You are, of course, in charge of how you manage your site, and I appreciate that. However, with great power...
 
<snipped> ...
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. :)

View attachment 413291

Merry Christmas, Amir.
Hi @restorer-john any chance you could publish the findings from your testing here? That would be interesting and a great addition to the information available to us?

Merry Christmas to you, and everyone :)
 
OK @amirm , we all can see that you find the 5 minute test at rated power useless. You have your reasons not to follow FTC regulation.

Another point - the preconditioning. FTC requests for 1 hour preconditioning at 1/8 of rated power into 8ohm, all channels driven.
Now we have that AIYIMA A07. With 48V power supply, the manufacturer claims 180W/8ohm rated power. However, the amplifier failed in 2 x 20W preconditioning in 14 minutes and at 2 x 10W in 54 minutes. And, 180W/8ohm is impossible to get with 48V PSU from the BTL design based on laws of electrical circuits, without huge >10% distortion. So, the manufacturer is a liar, dirty liar. My question is - you consider preconditioning useless as well? It would imply a conclusion that all tests that these little boxes do not pass are useless and that your tests have been tailored just for these little boxes, for some yet unknown reason.

 
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.
Hi @amirm Interesting to see this thread lurch towards possible changes to your test suite. I appreciate the challenges and have no real skin in this game - happy to see what comes out, if anything.

One question: do you think you could annotate your existing tests to make clear the duration of the tests and perhaps add a commentary
I've started looking at the test timestamps now, but I'm not clear about elapsed time for the test to complete vs time the DUT was actively working (or what conclusion to draw).
Perhaps I just need to read them again, but notes would be helpful.

Merry Christmas to you, and everyone :)
 
In the interest of establishing the facts, can you please re run the nc252 test? this time in accordance with the FTC parameters at 8 ohms load.
What parameters?Still don't know the test signal(s) .
Did anyone found out?

The European IEC 60.268-3 has very defined conditions,the US one on the other hand...
 
It is literally a 1970s view, in terms of attitude and technical understanding. The test is so badly formulated that it can end up harming the consumer interest. The major protaganists and advocates of the FTC test need to accept that an amplifiers ability to produce the rated power output with a real world music signals is not dictated by passing this 5 minute test. thats just technical ignorance. They need to accept it doesn't tell you anything about long term reliability. Figure out an appropriate test. Don't blindly accept or support beurocratic nonsense.
Your posts come across as quite angry and seem hastily written. Perhaps it's a language issue and not intended.

In any case, could you please explain how the FTC rule could harm consumer interests?
 
..and another.
Assuming we test the edges (20Hz and 20khz) we can safely conclude that anything in between will be right,ok?
Here's another problem though,depending the BW,what kind of generator has a totally clean 20kHz output so to feed the amp and not add up to the THD+N who will already be high (in case of D's,tubes,etc,AB's can get away with this)
 
Hello everyone. Just a short reminder for those members inferring that devices that pass this FTC test will be reliable or have greater longevity:

THIS IS NOT HOW YOU TEST RELIABILITY AND LONG TERM LONGEVITY.

Thank you.
 
I've started looking at the test timestamps now, but I'm not clear about elapsed time for the test to complete vs time the DUT was actively working (or what conclusion to draw).
The time stamps are the duration that the test took. I click start, AP remembers the time, and when it is finished with it, it captures the end time. So you know the full duration of the test. The amount of time spent in every point in the sweep however, is variable. Analyzer has programmable logic for how long it waits to get a stable value. Some products generate highly stable values at each point so measurement time is short (milliseconds). Otherwise change causing the analyzer to wait as much as 4 seconds (programmable). This however, happens when the measurement is noise related, not power.

Another complexity behind the scenes is the progression of points. Usually it is logarithmic, creating more points at low amplitude. In some cases though, it is linear which then tests a lot more at the limit. I now use the latter for headphone amplifiers so that the "knee" of the graph can be better captured. I could apply the same to power amplifiers but for the same reason as FTC tests, I am concerned about keeping the amp at, near and after clipping for too long.
 
Hello everyone. Just a short reminder for those members inferring that devices that pass this FTC test will be reliable or have greater longevity:

THIS IS NOT HOW YOU TEST RELIABILITY AND LONG TERM LONGEVITY.

Thank you.
However, it does provide a base for assessment of thermal performance. High temperature is a critical factor for assessing the lifespan of electronics, particularly electrolytic capacitors. Therefore, the test can indirectly indicate whether one might expect a shorter-than-expected component lifetime based on the temperatures reached during the test. However, temperature itself is not within the scope of the FTC tests, temperature monitoring would be up to third party testers, so it is not a long-term longevity assessment. Nonetheless, any issues that arise during the test, such as failing to complete the 1/8th power test, would be indicators of reliability.
 
Yes, it is not. But if the amplifier fails to pass preconditioning it indicates reliability issues quite certainly.
That's academic and you know it is. Please explain to the rest of the forum yor understanding of MTBF testing and application.
 
Amplifier Rule attached for those who want to read it themselves instead of being told what's in it from dubious sources.
 

Attachments

  • amplifier_rule_-_final_rule_notice.pdf
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However, it does provide a base for assessment of thermal performance. High temperature is a critical factor for assessing the lifespan of electronics, particularly electrolytic capacitors. Therefore, the test can indirectly indicate whether one might expect a shorter-than-expected component lifetime based on the temperatures reached during the test. However, temperature itself is not within the scope of the FTC tests, temperature monitoring would be up to third party testers, so it is not a long-term longevity assessment. Nonetheless, any issues that arise during the test, such as failing to complete the 1/8th power test, would be indicators of reliability.
Thank you. I've designed, analyzed and built mission-critical systems for which downtime of a a few seconds a year is unacceptable. Let me be clear, the FTC power amplifier test is irrelevant for longevity and reliability.
 
In any case, could you please explain how the FTC rule could harm consumer interests?
By eliminating low cost options that exist today. This is the Amazon listing for aforementioned AIYIMA A07 amp:

1733994475248.png

Imagine modifying this listing and saying it produces 20 watts because that is what the FTC test mandates. The market may shrink substantially for this amplifier (especially since there will be others selling similar units at "300 watts"). Their option would then be to substantially enhance the cooling in the cooling, power supply capability or both. This will sharply increase the cost of these amplifiers (shipping costs alone would be killer).

I would challenge FTC on this and bring up the above as Exhibit A that consumers were perfectly happy with what was being offered and advertised. 1400 reviews averaging 4.5 stars means there was nothing broken for FTC to "fix." Nobody using that amp thinks it is only spitting out 20 watts as they are using it in real life situation with music, hearing far more power.

In other words, government meddling in the industry, increasing costs with no net value to consumers. After all, the market is open to companies over-designing products if that was what the market wanted.
 
Alternatively force over engineering which increases cost. just to pass a test which has no bearing on reality of real world use. Neither situations help the consumer.

They absolutely help the consumer. Tell those consumers who are using 40-50 year old amplifiers still operating perfectly because they were built properly in the first place.

Contrast that with the few year old disposable amplifiers people make reliability threads about...

Let me be clear, the FTC power amplifier test is irrelevant for longevity and reliability.

The two are linked and you know it. An amplifier that can easily cope with the preconditioning and the 5 minute full power test must be adequately thermally designed. It must have adequate reserves in SOA and that means more devices. It must have an adequate power supply. All those things mean a less stressed, less hot device in normal use and that bodes well for longevity. Don't pretend otherwise.
 
Hi @amirm Interesting to see this thread lurch towards possible changes to your test suite.
To be clear, I have been thinking about design verification tests for a while. This thread has not had anything to do with it.
 
As Amir has already explained. Unecessarily force derating of an amp that functions just fine and reaches rated power with music signals. Alternatively force over engineering which increases cost. just to pass a test which has no bearing on reality of real world use. Neither situations help the consumer.
The test result is misleading. Take the reluctance of PMA to retest his nc252 in accordance with the FTC parameters. He is reluctant because he knows it will pass. Yet we know it will fail with a 4 ohm load. So how did the consumers benefit from the FTC test? it concluded all was golden.
As the rules are currently structured, there is no obligation for the manufacturer to alter their design, as they only need to add the FTC-rated power. They are free to disclose all their burst signal ratings as they wish. The value of the amplifier to the consumer is the exact same.
Can you explain how heating an amp to levels that would not be experienced in real world use during a one off 5 minute test can be extrapolated to indicate its MTBF?
We used the example of not completing the 1/8th power test as a basis for our discussion. If an amplifier cannot deliver 1/8th of its rated power into a resistive load, that suggests something significant. If this isn't indicative of questionable claims or reliability, then what is it?
 
OK @amirm , we all can see that you find the 5 minute test at rated power useless. You have your reasons not to follow FTC regulation.

Another point - the preconditioning. FTC requests for 1 hour preconditioning at 1/8 of rated power into 8ohm, all channels driven.
We have all said that the 300 watt rating or whatever is nonsense. I don't know why you keep bringing testing against that number.

What we are discussing is you saying the power ratings I measure are also nonsense. That unless an amp can produce them for 5 minutes, they don't count. Are you asserting that the amps can't produce 1/8 the power I measure???
 
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