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

With derailing this discussion that is over my head, is class B really an embodiment of that size or at all? examples?

That is a $4000 question! :D
 
No,I don't mind at all! :D

It just isn't my taste,I prefer black stuff.

They also state dynamic headroom,3dB,so double the whole stuff when needed.Not bad at all!
Interestingly, dynamic headroom was the only spec Erin questioned...

"...McIntosh’s “Dynamic Headroom” is rated at 3.0dB. If one were using my data then we see at 4-ohms the continuous power vs max peak (headroom/dynamic range) at 1% THD+N 546 watts and 823 watts, respectively (left channel). For a true 3dB of ‘headroom’ - which is doubling of power - the max peak power would have to be closer to 1092 (546w*2) or the max continuous would need to be 411.5 watts (823w/2)..."

He admits to being a Mcfanboy and ends up rationalizing why the amp missed the mark. For the price, would hope it is great. Would buy a Purifi amp and spend the remainder on some really nice speakers.
 
Doing what exactly? Playing sine waves? If so, go ahead and run that test and see how loud you can tolerate it and then run it for 5 minutes. Report back if amp goes into protection or dies.

If you mean playing music, then do the same and report on that.

Amplifiers are simply not shutting down for people after 5 minutes of playing music or they wouldn't be able to sell much or any.
Many discussions on this topic don’t really try to understand different viewpoints. People jump to conclusions and focus on proving their points or questioning others' knowledge instead of having a productive conversation. This is especially true for rhetorical questions of the kind, which everyone here probably already knows the answers to and thus don’t really help move the discussion forward. :)

Regarding amplifier performance, it is reasonable to expect an amplifier to sustain its rated power for at least five minutes. If it cannot meet the claims presented in its specifications or advertisements, these claims could be considered misleading.

The current method for determining power ratings is open to discussion. While sine wave testing may not reflect real-world music signals and can be taxing on amplifiers, it is the established standard for performance evaluation. Addressing it might involve an additional labeling "FTC-rated power," and then supplementing it with additional labels, disclosing alternative metrics that better represent real-world performance.

In an effort to move the discussion forward, here are some questions to consider:
  1. Do you believe you, Amir, have the ability to influence changes to the FTC’s amplifier testing regulations? (This is an honest question, as your reach in this area is not clear to me.)
  2. If the FTC rule cannot be changed, would you:
    A) Choose to disregard it altogether, or
    B) Continue by testing amplifiers in line with FTC standards?
  3. Would you instead consider advocating for a more practical power rating system that better reflects the real-world performance of amplifiers, particularly Class-D designs?
Of these options, pursuing a more realistic testing method (question 3) could provide valuable insights for enthusiasts and specialized communities. However, for general consumers, adherence to the FTC standard may offer the clearest and most widely accepted benchmark for amplifier performance. While alternative methods may improve accuracy, their broader impact on market transparency could remain limited without widespread adoption.

So, Amir, you have access to a hive-mind. Perhaps it would be beneficial to utilize it by exploring different signals and testing protocols that more accurately reflect real-life scenarios?
 
Reading this document with understanding should close this ineffective yet emotional discussion.
It would be more enlightening if Hypex purify and TI et all could explain thier modelling for this .
Especially projected life cycle , how long is it built to lasts in thier models ? Forever, a decade, The warranty period?

They are not wrong in practice . They probably fine tuned their model over the years if returned modules started to pile up …

But one wise guy somewhere quoted that all models are wrong but some are useful. Would the dimensions of hypes output filters change if their models included more electronic music ? I think so . It’s an average probably a Gaussian distribution somewhere in it .

And there are always outliers. With this “practical use model “ approach there will some rare cases where the product would not fit where the model breaks down . Hopefully it happens within the warranty period, but one has still wasted a valuable consumers time and effort?

It hurts my engineering brain a bit to not deal in more deterministic and absolute terms ( forget the FTC rule what I say is not ultimately about a specific set of test conditions ).
A more instrumental approach is to treat the amplifier as a box that accepts small AC voltages within a specified bandwidth and outputs a larger AC voltage and is also capable of delivering that voltage into some specified lowest impedance .
And no assumptions made about what said input signal is given that it’s inside the bandwidth ( as models are always wrong and assumptions can’t be made ).
Yes if some mfg is brasen enough to spec 0-100kHz that makes DC a valid input signal ;) ( it’s a bit stupid to don’t have dc protection ).

I’m a bit ambivalent.

I would trust the models more if they could be shown and explained to me and if sufficient margins where in in place so failures where extraordinary rare and product longevity not hurt . And expected life time disclosed.

Personally I made the leap of faith to agian buy active speakers and subwoofers , the have no chance at all to run thier amps in any continuous capacity. The treble amp is smaller but actually class AB the rest is class-D bass midrange and subwoofers . The mfg made thier assumptions about this :)
 
Interestingly, dynamic headroom was the only spec Erin questioned...

"...McIntosh’s “Dynamic Headroom” is rated at 3.0dB. If one were using my data then we see at 4-ohms the continuous power vs max peak (headroom/dynamic range) at 1% THD+N 546 watts and 823 watts, respectively (left channel). For a true 3dB of ‘headroom’ - which is doubling of power - the max peak power would have to be closer to 1092 (546w*2) or the max continuous would need to be 411.5 watts (823w/2)..."

He admits to being a Mcfanboy and ends up rationalizing why the amp missed the mark. For the price, would hope it is great. Would buy a Purifi amp and spend the remainder on some really nice speakers.
Yep,and it even falls short by their rating (450W so it should be 900W) .
I'm not Mcintosh fanboi,too colorful for me (I'm talking appearance,very important to me) ,I would prefer their engineering in a black Audio Research case if I was up for VU's.

But aside from all that,it delivers,that's the truth,
And since we are well beyond audibility with this stuff and engineering is all that matters,it beats Purifi up high,inevitably and looses big time at efficiency.
Price,I don't care,an equally nice looking Purifi with thermals to deal with every conditions at the same power would not be very far I guess.
 
  1. Do you believe you, Amir, have the ability to influence changes to the FTC’s amplifier testing regulations? (This is an honest question, as your reach in this area is not clear to me.)
Potentially. It would require member attorneys wanting to file a lawsuit against them. Alternatively, I have thought of reaching out to CTA as they would have the resource for this. From a practical point of view though, we should wait to see if they lift a finger to enforce anything.
  1. If the FTC rule cannot be changed, would you:
    A) Choose to disregard it altogether, or
    B) Continue by testing amplifiers in line with FTC standards?
Before this discussion came up, I was already thinking about stressing amplifiers more. You have seen one example of such tests show up recently:

index.php


I am motivated to refine this test and maybe add something else that serves the purpose. Once there, we can then work on getting the industry to adopt it. This would help with objecting to FTC by showing willingness to solve the problem.

I have no intention whatsoever to run a 5 minute max power test at full bandwidth.
  1. Would you instead consider advocating for a more practical power rating system that better reflects the real-world performance of amplifiers, particularly Class-D designs?
I prefer to not create a special test for class D.
 
There is zero mention of it running at full power for 5 minutes. The TO-3 transistors are laying flat instead of properly being mounted on the side heatsinks. The thermal impedance as a result, is much higher, necessitating that fan in the back. The fan is poorly located with no fluid dynamics analysis for proper air circulation. To be sure, it does a lot more than nothing but not remotely proper.

Get a modern PA amp and it too, with a fan, will run reliably, producing gobs more power than it. And it would sell for a fraction of what that amp cost.

And oh, they break down as well, lest you once again be claiming that the older amps didn't break. Here is a quick google search: https://www.diyaudio.com/community/threads/perreaux-8000c-left-channel-not-working-need-help.325666/

"I have a Perreaux 8000c ..lately the left channel started to get crackly and staticky and also little pop sounds .I have to mention that I have 3 6000c as well that have very similar symptoms "

To claim that the older amps didn't break is absurd. The only thing more absurd is claiming that after decades, they are still reliable. All amplifiers break. I actually trust the class D ones far more because a) they run so much cooler and b) they are so easy to repair with a module swap.

Give it up Amir. You're becoming more ridiculous with each post. It's pretty funny actually.

You are demonstrating just how little you know about Perreaux amplifiers, the company, the founder (Peter Perreaux) and just how reliable they were. They are merely an example I used. I have hundreds of other examples I could use.

And you are now attempting to re-write and misrepresent what I have said. Most members here are smart enough to see through that.

I have no intention whatsoever to run a 5 minute max power test at full bandwidth.

And there you have it folks. We knew this all along.

So you'll obviously be putting a nice fat disclaimer on the power output test results saying "This amplifier was not tested under the FTC standard" lest someone looking to purchase, based on your technical reviews could potentially be misled as to the actual continuous available power of the product? Should be a fun time for all.
 
You are demonstrating just how little you know about Perreaux amplifiers, the company, the founder (Peter Perreaux) and just how reliable they were. They are merely an example I used. I have hundreds of other examples I could use.
I think I am going to grow old and die before you show us a single, full power, full bandwidth test of any amplifier for 5 minutes.....
 
So you'll obviously be putting a nice fat disclaimer on the power output test results saying "This amplifier was not tested under the FTC standard" lest someone looking to purchase, based on your technical reviews could potentially be misled as to the actual continuous available power of the product? Should be a fun time for all.
FTC rule is not a standard. It is a regulation created by lay people at a government agency with no understanding of the underlying technology or even the test itself. A standard is created by technical people through many stages. Nothing remotely like that happened with FTC. As I mentioned, FCC (Federal Communication Commission) does that kind of work in the way it uses other major standards organizations for transmission and TV technologies. FTC (Federal Trade Commission) is a trade watchdog and should stay out of creating ad-hoc rules that are bad for both consumers and companies.
 
And you are now attempting to re-write and misrepresent what I have said.
There is nothing to misrepresent. You keep championing something that you haven't practiced at all. Ditto for @pma and his random tests. Not a single company, reviewer, or organization has shown a single test result per FTC 2024. The ruling is not practicable much less useful.
 
I'm hearing three threads in this discussion;

#1 FTC regulation: definition / utility. I now see this as pretty academic. Interesting to follow.

#2 ASR testing for amplifiers: can they be revised to better indicate power capability. I'm hopeful that change is coming.

#3 Amplifier reliability/longevity. This is regularly touched on but I'm not sure anything concrete is coming out.

On longevity, it's clear that thermal management is key. There's talk about measuring the temperature of amps being tested - helpful.

I wanted to ask about temperature at idle, which @restorer-john raised in a mis-titled thread (class D efficiency) ages ago and which @amirm raised earlier in this thread.
If elevated idle temperature, in Amp and power supply, is what slowly cooks components and reduces amplifier life - can that be measured too?
 
You are demonstrating just how little you know about Perreaux amplifiers, the company, the founder (Peter Perreaux) and just how reliable they were.
I don't care if Moses came down and handed the amplifier to each one. Every amplifier fails. You have hard data saying otherwise, let's see it.
 
On longevity, it's clear that thermal management is key.
We don't know this. Amplifiers fail for many reasons. Some just fail to turn on one day. Some component can just fail for random reason. Or have the amp get subjected to conditions not tested. Standard protection circuit shuts down the amp if it is getting too hot.

Long term, yes, caps can dry out and such. But we can't do failure analysis so simply.
 
If elevated idle temperature, in Amp and power supply, is what slowly cooks components and reduces amplifier life - can that be measured too?
One doesn't know the quality and rating of the capacitors used. It really goes beyond any kind of quick analysis.

Such testing is best left to manufactures. Sony for example would cook dozens of units in a room overnight and see if the failures follow any pattern or are above certain rate.
 
I'm finding the lack of respect and ad hominems in this thread particularly unpleasant. If I invited you to my house and you spoke to me in the way I am seeing some here speak, I wouldn't be offering a second invitation.

Let's cool it down a little.
 
We don't know this. Amplifiers fail for many reasons. Some just fail to turn on one day. Some component can just fail for random reason. Or have the amp get subjected to conditions not tested. Standard protection circuit shuts down the amp if it is getting too hot.

Long term, yes, caps can dry out and such. But we can't do failure analysis so simply.
Fair enough, I was simplifying - went too far. I still think that thermal management is an important factor at idle and at higher power levels but I take your point.
 
One doesn't know the quality and rating of the capacitors used. It really goes beyond any kind of quick analysis.

Such testing is best left to manufactures. Sony for example would cook dozens of units in a room overnight and see if the failures follow any pattern or are above certain rate.
Agreed.

If reviewers here are doing a tear-down, is a comment on components, heat sinks and the layout appropriate - or even sensible to attempt.

I don't have the knowledge to look at the inside of an amp and assess that so I'm looking to borrow the experience of members here.

I could just read a book I suppose!
 
Fair enough, I was simplifying - went too far. I still think that thermal management is an important factor at idle and at higher power levels but I take your point.
High power amps (NCx500,icepower 1200as,etc) are warm even at idle (but strangely cool down when play a little louder,not max though) while low power ones usually (I say usually,don't take fosi's monos for example) are cooler.Nicer ones like Purifi are cooler,but I don't know about their high power one,still haven't put my hands on it)
Same for AB's,it depends on the power mostly (that's all out of experience,so disclaimer)
 
As a side note I would expect to have the informed opinions of the other side at this thread,there's a bunch of them otherwise very vocal,both assemblers and designers.
They must have some more info about it.
Don't want to tag them but silence is strange.I would expect they were the first to participate.
 
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