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

[SIY]

In (some) seriousness, @SIY, what would you select as an average passive loudspeaker? Not puttin' you on the spot -- just curious? Should we weight by sales numbers (i.e., market penetration)? So, maybe, some KEF product?

A model load based on offerings from people like KEF or Bose or JBL or Polk or... whatever are the big sellers. I mean, they sell in an hour what any of the niche brands you mention sell in a year.

 

[Sokel]

A model load based on offerings from people like KEF or Bose or JBL or Polk or... whatever are the big sellers. I mean, they sell in an hour what any of the niche brands you mention sell in a year.

The new trend is this:



(link)

And we're talking about a really small speaker.
But is as modern as it gets with all the other boxes ticked,that's why all the interest.

I don't know if their bigger Purifi models follow the same route but it's interesting.
One would think at this age and time that everything has to become more efficient and save energy,the new small speakers are very insensitive and on top of that we see some difficult ones like this one too.

 

[tmtomh]

The new trend is this:

View attachment 412157

(link)

And we're talking about a really small speaker.
But is as modern as it gets with all the other boxes ticked,that's why all the interest.

I don't know if their bigger Purifi models follow the same route but it's interesting.
One would think at this age and time that everything has to become more efficient and save energy,the new small speakers are very insensitive and on top of that we see some difficult ones like this one too.

I think part of @SIY 's point here is that we shouldn't take a single speaker's impedance curve and assert that it's a "trend" without making it part of a more systematic analysis of the data.

There are very difficult speaker loads out there, for sure, 100% agree. How common are they? So far all we have is pseudo-quantitative assertions based on qualitative impressions and single examples.

Not to mention, if we're going to raise individual speaker models whose impedance dips low, then by the same token we could just as easily post graphs from @amirm 's reviews of several modern amps, including some very inexpensive ones, that do quite well in his 2 ohm testing.

So without a more systematic survey, it seems like we're just doomed to a battle of anecdotes and small data points.

 

[Sokel]

I think part of @SIY 's point here is that we shouldn't take a single speaker's impedance curve and assert that it's a "trend" without making it part of a more systematic analysis of the data.

There are very difficult speaker loads out there, for sure, 100% agree. How common are they? So far all we have is pseudo-quantitative assertions based on qualitative impressions and single examples.

Not to mention, if we're going to raise individual speaker models whose impedance dips low, then by the same token we could just as easily post graphs from @amirm 's reviews of several modern amps, including some very inexpensive ones, that do quite well in his 2 ohm testing.

So without a more systematic survey, it seems like we're just doomed to a battle of anecdotes and small data points.

I totally agree to all the above.
I just pointed out that the pathological loads of the past are not only there.Same with the ridiculously insensitive designs.
Heck,not only on speakers,people drive headphones with power amps!

So yes,loads should be different,there's too much out there at both ends.

Edit: @SIY mentioned KEF as an example:



and it's tiny!

Read Amir's comment below the chart.

 

[pma]

From my past experience here, testing with R//C, R+L, R//(C+L+R), (R+L)R//L//C) has never been of much interest here. It always ended at 4 or 8 ohm resistive and preferably 5W/1kHz SINAD. So, frankly, I have no expectations. The only exceptions are power cube tests, but they rather say passed/failed and not much about distortion into complex load.

Not to many people doing the real job here, rather debating. Then, exchange of experience is close to impossible.

 

[RickS]

From my past experience here, testing with R//C, R+L, R//(C+L+R), (R+L)R//L//C) has never been of much interest here. It always ended at 4 or 8 ohm resistive and preferably 5W/1kHz SINAD. So, frankly, I have no expectations. The only exceptions are power cube tests, but they rather say passed/failed and not much about distortion into complex load.

Not to many people doing the real job here, rather debating. Then, exchange of experience is close to impossible.

Am not at your level of course but like others, use the stepped sine test in REW to create Power vs THD graphs. From that, know it is more than capable of creating significant heat with a 4R dummy load without being as severe as a 5-minute continuous test. 

Amir's testing is certainly more stringent than the REW test and so can see why he might draw a line on the need for a continuous test. Personally, would like to see more discussion over what an ASR standard power test should be since the FTC regulation is not highly regarded.

 

[SIY]

Edit: @SIY mentioned KEF as an example:

3.7 ohm isn't too harsh at all, especially compared with stuff seen in niche brands.

 

[Sokel]

3.7 ohm isn't too harsh at all, especially compared with stuff seen in niche brands.

It's not on its own,but combined with its 83dB sensitivity it's not the easiest out there either.
It was just an example of trade-offs.One would expect engineering would be able to do 100dB sens perfect speakers after 100 years* ,etc.

They instead rely on amps because power is cheaper these days.Then amps rely on most music's nature in their turn to cut corners too.
And so on...

*Edit: at a funny note as I said 100 years,my gramophone (1913) does 70-75dB (A) SPL with NO power (other than the one I store to it by winding its thingie )

 

[RickS]

I think part of @SIY 's point here is that we shouldn't take a single speaker's impedance curve and assert that it's a "trend" without making it part of a more systematic analysis of the data.

There are very difficult speaker loads out there, for sure, 100% agree. How common are they? So far all we have is pseudo-quantitative assertions based on qualitative impressions and single examples.

Not to mention, if we're going to raise individual speaker models whose impedance dips low, then by the same token we could just as easily post graphs from @amirm 's reviews of several modern amps, including some very inexpensive ones, that do quite well in his 2 ohm testing.

So without a more systematic survey, it seems like we're just doomed to a battle of anecdotes and small data points.

We should still be able to do better than the FTC.

 

[amirm]

Not to many people doing the real job here, rather debating. Then, exchange of experience is close to impossible.

Experience? What experience do you have driving government regulations? Or running an audio/technology company? Or having responsibility over big chunk of the industry? Your comments lack wisdom in all of these areas and that is the topic at hand here.

From my past experience here, testing with R//C, R+L, R//(C+L+R), (R+L)R//L//C) has never been of much interest here. It always ended at 4 or 8 ohm resistive and preferably 5W/1kHz SINAD. So, frankly, I have no expectations. The only exceptions are power cube tests, but they rather say passed/failed and not much about distortion into complex load.

Oh? So now running a dozen tests against the reactive load is not enough to test stability, current availability, etc. is not it. But a one liner 5 minute test into 4 ohm resistive load is?

If I thought for a moment you had genuine concerns to raise, I would listen to you more. Instead, it is a all negativism and complaining.

 

[ssn22]

It's also good to leave everything to time
False can be over a period of time
Fake like the real thing
But the truth can never be false
You can fool everyone for a while
Or you can fool a few at all times
But you can never
Fool all the people all the time
And then that's the truth

 

[Sokel]

Talking about time,AP has a nice article (maybe a little unrelated) about how important is time measurement for accuracy:

Measurements are Estimates

www.ap.com

 

[restorer-john]

(a trio of cheap "15xx series" marantz receivers -- lacking even Gyro-touch tuning. )

You do know the 15xx series were actually way better designed, higher performing and much better made in real terms than the 22xx series don't you? The 15xx series is classic under appreciated late 1970s SRC Marantz at its best, just before Philips came in and made a mess of it all.

They were deep into cost cutting, like everyone else, but the circuitry, componentry and ultimate performance were considerably better that what came before.

Look at the tuners in those receivers. The 15xx series had the latest Matsushita FM ICs that blew the old Hitachi based front ends out of the water.

"gyro-touch" was simply a horizontal tuning wheel- that's all. Nothing special and certainly not better in any way. I would argue it was worse than a proper flywheel. Have you ever tried to spin a gyro-touch from one end of the dial to the other? It doesn't.

Actually, there's a 1550 here someplace. Dug it out of the storeroom a few years ago. Maybe I'll test it. Batwings IIRC.

 

[restorer-john]

I can tell crap made audio products from a mile away.

Sadly not, Amir.

Should I remind you of the "crap made" audio amplifier products you have gave your highest recommendations to, based on your limited testing, which ultimately turned into complete reliability dogs?

You might know the brand, it starts with a capital "T".

Just do the 5 minute full bandwidth, full rated power tests. It's not hard. And report the outcomes- every time.

 

[pma]

Reliability, thermal design sufficiency, compatibility (EMC) - nothing of that is tested in the official ASR reviews and products get recommended even if the may make gross disappointment to their users.

 

[tmtomh]

Reliability, thermal design sufficiency, compatibility (EMC) - nothing of that is tested in the official ASR reviews and products get recommended even if the may make gross disappointment to their users.

You and @restorer-john have absolutely, positively no idea if the Topping PA5’s reliability issue would have been revealed by the 5-minute test you want @amirm to do - and you both know it. And neither of you will ever admit it. Instead you will deflect and say that’s not the point and there are other ways to test reliability and it’s not just that amp and on and on and on.

It’s not that you don’t have a point - you do. It’s that neither one of you ever takes any accountability for the uncorrect, selective, or misleading claims that you make.

 

[miero]

The ratings above reviews could be extended with additional options for people who have purchased the reviewed product. This could tell a hands on experience.

 

[Old_School_Brad]

You and @restorer-john have absolutely, positively no idea if the Topping PA5’s reliability issue would have been revealed by the 5-minute test you want @amirm to do - and you both know it. And neither of you will ever admit it. Instead you will deflect and say that’s not the point and there are other ways to test reliability and it’s not just that amp and on and on and on.

It’s not that you don’t have a point - you do. It’s that neither one of you ever takes any accountability for the uncorrect, selective, or misleading claims that you make.

That seems a bit harsh, if I may say so. The FTC test will undoubtedly expose thermal shortcomings, but reliability? Likely not. How could a short test uncover such an issue? If an amplifier's problems are tied to its thermal design, the test would probably highlight them; otherwise, it's unlikely. I'm not aware of the exact issues of the Topping amplifier.

PMA did raise a valid point about emissions, in my opinion. If I were in the market for an amplifier and this was the one I was considering, I’d dismiss it immediately, even if it performed flawlessly in all other aspects. Who wants a device in their home that interferes with WiFi and Bluetooth? On the other hand, it does come with its own wireless music transfer system...

 

[pma]

20V peaks with rise time about 50ns behind the speaker cable directly at speaker box terminals, (both differential and CM interference voltages)

https://www.audiosciencereview.com/forum/index.php?attachments/img_3520-jpeg.412089/

AM radio demodulating the signal in the whole listening room - such product like SMSL A100 could never meet EMC compliance. There is no space for excuses, this is how those far east producers do not care about standards. And the people are still protecting their behaviour, just because the products are cheap.

A100 is a class D without output filter. Output voltage is a train of BD modulated impulses

https://www.audiosciencereview.com/forum/index.php?attachments/smsl_a100_scope-png.412062/

You feed the amp with sine but output is as shown above. It is the speaker that makes the low pass filtration at acoustic side. And you have a good CB transmitter.

This is for 10kHz sine input. A and B channels are voltages at +OUT and -OUT against COM. A-B is what sees the speaker. Impulses with carrier frequency of about 660kHz, with always full amplitude. Impulse width is proportional to input amplitude. CM voltage interference impulses amplitude is 24V (PSU voltage). That is how the filterless class D with BD modulation works.

 

[mhardy6647]

You do know the 15xx series were actually way better designed, higher performing and much better made in real terms than the 22xx series don't you? The 15xx series is classic under appreciated late 1970s SRC Marantz at its best, just before Philips came in and made a mess of it all.

They were deep into cost cutting, like everyone else, but the circuitry, componentry and ultimate performance were considerably better that what came before.

Look at the tuners in those receivers. The 15xx series had the latest Matsushita FM ICs that blew the old Hitachi based front ends out of the water.

"gyro-touch" was simply a horizontal tuning wheel- that's all. Nothing special and certainly not better in any way. I would argue it was worse than a proper flywheel. Have you ever tried to spin a gyro-touch from one end of the dial to the other? It doesn't.

Actually, there's a 1550 here someplace. Dug it out of the storeroom a few years ago. Maybe I'll test it. Batwings IIRC.

I did not know that, John! The gyro-touch comment was pure snark on my part. I am not a big fan of the Superscope and Standard Radio era (Chatsworth-era) of marantz.