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

Wait, the A07 should be max power of about 61W at 8R with the 48V brick supply (maybe a bit higher with the 48V you are using). So the preconditioning should be about 7.6W. So the problem is the manufacturer rating of 180-190W is bogus, probably at 10% distortion or just a plain lie.

edit: how much short-term power can you get it to do into 8R with your bench supply at 48V (now I notice the one Amir used was just 3A)?

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So. Its size constraints make it a 20 W continous amplifier.
Unfortunately, you are still too optimistic. With 48V power supply and exactly 2 x 20W / 8ohm, the amplifier shut down after 14 minutes, being cooled down before the test. I have a 48/16 wav record, if you wanted to see it, but it is about 78MB.

I think next step I am going down to 2 x 10W.

I am attaching a screenshot of the failure point.

A07_failure_record.png

To the others - facts, not opinions, not emotions.
 
Wait, the A07 should be max power of about 61W at 8R with the 48V brick supply (maybe a bit higher with the 48V you are using). So the preconditioning should be about 7.6W. So the problem is the manufacturer rating of 180-190W is bogus, probably at 10% distortion or just a plain lie.
View attachment 413136
They are quoting Texas Instrument’s spec page. Without noting the cooling requirements to reach those power levels. So they are right in that the 3255 can do 300 watts stereo. But it can’t as implemented by Aiyima. So also lying. This is where the FTC rule might be helpful. It would force assemblers to rate not the chip, but the implementation. Unfortunately, as someone trying to implement a test to fit the rule, the rule is written really poorly. As written, I have to test at ALL frequencies ( which is impossible) or devise my own sample of frequencies that I believe will account for ANY single frequency being tested. Much more doable, but I’m staking a lot on the sample, both in terms of testing time and in terms of making sure it captures the needed data for any frequency to work.

If the FTC is going to enforce this rule, it would be better modified to spell out a standard test by specifying frequencies to test at and test conditions for each frequency.
 
Unfortunately, you are still too optimistic. With 48V power supply and exactly 2 x 20W / 8ohm, the amplifier shut down after 14 minutes, being cooled down before the test. I have a 48/16 wav record, if you wanted to see it, but it is about 78MB.

I think next step I am going down to 2 x 10W.
Does it do 61W for 5 minutes (edit: surely not if it can't do 20W for 15 min)? To me it seems that the manufacturer's max power rating should be for when paired with the power bricks they provide, not 48V/10A.
 
Unfortunately, you are still too optimistic. With 48V power supply and exactly 2 x 20W / 8ohm, the amplifier shut down after 14 minutes, being cooled down before the test. I have a 48/16 wav record, if you wanted to see it, but it is about 78MB.

I think next step I am going down to 2 x 10W.

I am attaching a screenshot of the failure point.

View attachment 413138

To the others - facts, not opinions, not emotions.
I comes at no surprise with its little box, really, so I have no reason to doubt it.

So. Its size constraints make it a 20 10-15 W continuous amplifier.
 
Look here

Thanks! Missed it as is an almost 4 year old review and lots of Aiyama reviews since then. Some of which are A07s that did not get recommended.

Wait, the A07 should be max power of about 61W at 8R with the 48V brick supply (maybe a bit higher with the 48V you are using). So the preconditioning should be about 7.6W. So the problem is the manufacturer rating of 180-190W is bogus, probably at 10% distortion or just a plain lie.
View attachment 413136

So, Amir's testing shows this little amp does not do close 300 watts and his outlandish crime is still recommending it despite some middling test results and only costing $72? His review does mention the power rating discrepancy AND that "aggressive" protection kicked in.

Lol, now that it failed Pavel's FTC test, am sure the sales are going to plummet!;)
 
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Does it do 61W for 5 minutes? To me it seems that the manufacturer's max power rating should be for when paired with the power bricks they provide, not 48V/10A.
It consumes the power it requires, independent of the power supply if it's sufficiently sized. In this case, the power supply is, shall we say, over-sized.
 
My original A07 and A04 amps are still going strong, the A07 gets plenty loud even with a 32v power supply. I think the original published power specs are bogus, but it seems to be a fine little amp if used with reasonable power and at reasonable volumes.

I don't think it's bad to point out that the stated specs are pretty ridiculous, but I have no idea how to get overseas manufacturers selling worldwide to agree upon a uniform testing suite and thereby have to downgrade what they are claiming...that's probaly just not going to happen. So, as always, buyer beware and read some reviews and real user reports before purchasing (as I try to do).

I think Amir's reviews are very helpful in calling out the truly bad stuff and stuff that is marginal...
 
So, Amir's testing shows this little amp does not do close 300 watts

Bear in mind, Amir's test was done with a 3A PSU - not the 10A specified in Aiyima's table quoted by @pma above. He also states power at the corner of the distortion curve, not at the 1% and 10% levels used by the manufacturer.
 
They are quoting Texas Instrument’s spec page. Without noting the cooling requirements to reach those power levels. So they are right in that the 3255 can do 300 watts stereo. But it can’t as implemented by Aiyima. So also lying. This is where the FTC rule might be helpful.
This is where Amir's graphs are useful. Given the measured performance he wrote "Yes, the 300 watt rating is a fantasy..."

The recommendation does not mean Amir signs off on this daft power rating. What new information would failing the FTC tests add to what he already provided?
 
his outlandish crime is still recommending it despite some middling test results and only costing $72?
I don't have a problem for Amir recommending. I just think it would be nice to check if these things can do the max power (as determined by Amir) for a few minutes. At least the amps sent by the manufacturer.
 
This is where Amir's graphs are useful. Given the measured performance he wrote "Yes, the 300 watt rating is a fantasy..."

The recommendation does not mean Amir signs off on this daft power rating. What new information would failing the FTC tests add to what he already provided?
Personally, I’m doubtful any FTC rule would be beneficial over the extensive tests already done here and elsewhere. They might be beneficial in curbing some of the more egregious claims of manufacturers for those who take manufacturing claims at face value.

I’m just trying to figure out an FTC compliant test so I can run it on my functional PA5 to see if it forces the design flaw to emerge, as was claimed it would upthread.
 
Personally, I’m doubtful any FTC rule would be beneficial over the extensive tests already done here and elsewhere. They might be beneficial in curbing some of the more egregious claims of manufacturers for those who take manufacturing claims at face value.

I’m just trying to figure out an FTC compliant test so I can run it on my functional PA5 to see if it forces the design flaw to emerge, as was claimed it would upthread.
I agree better for Amir to decide how to test than go by FTC. Maybe just do 5 minutes at max power both at 8R and 4R? (but not on stuff sent in by ASR members).
 
Bear in mind, Amir's test was done with a 3A PSU - not the 10A specified in Aiyima's table quoted by @pma above. He also states power at the corner of the distortion curve, not at the 1% and 10% levels used by the manufacturer.

Thanks, I noticed and also noticed Pavel does not specify the current ratings on his.

I don't have a problem for Amir recommending. I just think it would be nice to check if these things can do the max power (as determined by Amir) for a few minutes. At least the amps sent by the manufacturer.

Am not sure what all the outrage is frankly (as reviewer, Amir makes the overall call). As Amir posted, the tests he currently does already do stress the amp for minutes. The requirement is very different for a power rating test than for a reliability test. Have you seen a published reliability spec on a consumer amplifier? I have not.
 
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Thanks, I noticed and also noticed Pavel does not specify the current ratings.


Am not sure what all the outrage is frankly (as reviewer, Amir makes the overall call). As Amir posted, the tests he currently does already do stress the amp for minutes. The requirement is very different for a power rating test than for a reliability test. Have you seen a published reliability spec on a consumer amplifier? I have not.
I am not outraged. Are you outraged? I will fake some outrage as an excuse to have a beer to calm me down though.
 
@pma correct me if I am wrong, the nc252 is rated at 150 watts into 8 ohms so should be pre conditioned at 18.75 watts.
50W continuous on the data sheet, right? Won't most Class D that fail the preconditioning also fail the 5 minutes at max power test? So then why not go straight to the 5 min max power test?
 
I am not outraged. Are you outraged? I will fake some outrage as an excuse to have a beer to calm me down though.

No, however I am disappointed when those that proclaim superior knowledge and skills misrepresent facts.

Product reliability is usually expressed by MTBF or MTTF ratings. These tests are often destructive and do require special equipment to perform. I think it is disingenuous to suggest that a test intended to determine performance is a dependable substitute for industry standard practices for reliability testing. Are they somewhat related and dependent? Yes, but is like suggesting your car's horsepower determines when the engine might fail. EDIT: As with other aspects of the FTC test, this analogy is an oversimplification.
 
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I think next step I am going down to 2 x 10W.
Almost, almost passed the preconditioning! :D:facepalm:
Isn't it great! This, beloved, 2 x 180W / 8ohm rated power amplifier (with 48V PSU) has almost passed the preconditioning at 2 x 10W/8ohm which is 1/18 of the rated power, and failed no sooner than after 54 minutes, being very hot on the top cover. Great! We have a 2 x 10W amplifier with peak power 2 x180W (just maybe). What a wonderful dynamic reserve! And how well it behaves in some garage! Such is the truth of these toy box amplifiers.

A07_failure_10W_record.png
 
No, however I am disappointed when those that claim superior knowledge and skills misrepresent facts.

Product reliability is usually expressed by MTBF or MTTF ratings. These tests are often destructive and do require special equipment to perform. I think it is disingenuous to suggest that a test intended to determine performance is a dependable substitute for industry standard practices for reliability testing. Are they somewhat related and dependent? Yes, but is like suggesting your car's horsepower determines when the engine might fail.
If we insist on using car analogies for some reason, I believe it’s more like a 200 HP engine that overheats and breaks down on the highway, even though the car was driving within the speed limit and only using 50 HP.
 
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