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

[pma]

Then look for products that have FCC compliance. No random testing by an individual in an uncontrolled situation testifies to that.

Could not find it in FCC database.

Some individuals have at least some knowledge, capabilities and background directly in the field of interest, some not.

 

[pma]

I found a very detailed FCC report for SMSL products, including A100 performed by BCTS technologies. You can see the extensive testing performed: https://fccid.io/2ASLV-A3/Test-Report/Test-Report-4201522

This is all for the Bluetooth interface so they are covered there (you can reuse certification in multiple products if the module is the same). So they are covered in that respect.

The amp itself, I am not sure.

Speaker cable (C-2) length used was 0.5m. Similar is recommended in the MA12070 manual for filterless operation.

P.S.: And it was tested by Shenzhen BCTC Testing Co., Ltd.

The test report applies rather to the RF module common for all listed devices than specifically to SMSLA100 amplifier.

 

[JeremyFife]

There is no standard or standard test for the FTC rule. It is an ad-hoc regulation with zero research into its efficacy. It is pure opinion and that of lay individuals working at FTC.

Is there a standard test (or a useful test that could become standard) that can be added to the ASR amplifier suite that would indicate continuous power capability and the effectiveness of thermal management?

 

[amirm]

Could not find it in FCC database.

I had no trouble finding it. The one I referenced is 2ASLV-A3. I post the link to the report already.

Some individuals have at least some knowledge, capabilities and background directly in the field of interest, some not.

Seems like in this case you don't know that their corporate name is FoShan Shuangmusanlin technology. It took me 2 minutes to find the complete, detailed report.

 

[amirm]

Is there a standard test (or a useful test that could become standard) that can be added to the ASR amplifier suite that would indicate continuous power capability and the effectiveness of thermal management?

We could use a more real life signal and agree on duration. To do this properly though, you need a climate controlled chamber so that the ambient temp is always the same. Otherwise the results won't be repeatable and comparable. We are probably looking at $15K for the chamber. These things are like small fridges and I just don't have the space for it in the lab.

The bigger issue is the time constraint on me. I am currently not able to keep up with testing workload. I am constantly way behind in getting products tested. Do you want to see more speakers tested or have some semi-accurate thermal testing of amplifiers?

 

[amirm]

How many people here have amplifiers that are either shutting down or have died due to getting too hot? And have you tried to just put a fan on top of it?

 

[Astoneroad]

Do you want to see more speakers tested or have some semi-accurate thermal testing of amplifiers?

If you're putting it to a vote, I vote for more speakers. Perhaps a thread for such a vote?

 

[pma]

Infeon Merus passed the EMC test with MA12070 (used in SMSL A100) reference board with 10cm speaker wires

https://www.infineon.com/dgdl/Infineon-UserManual_ClassD_audio_MA120xxx_reference_boards-ApplicationNotes-v01_01-EN.pdf?fileId=5546d46269bda8df0169da3392a743bd

(page 19-23)

SMSL A100 uses no special EMI filtering, except for ceramic capacitors - PCB and 12070 going directly to L-, L+, R-, R+. There is also no inductor between the board connector and binding posts. And the measured rectangular output impulses with Tr < 50ns are a technical proof that cannot be questioned.



TI produces similar filterless class D range TPA31XX that I tested a year ago. And below are their notes on FCC test and recommendations on EMC measures.

 

[restorer-john]

Question for advocates of FTC regulation:

Let's take an amplifier built on Hypex NC500 OEM module. Company specs are such:

Peak Output Power 1KHz, THD=1%, all channels driven. Per channel: 4Ω - 700 - W
Continuous Output Power Per channel,25°C ambient temperature: cont - 100 - W

Note one after the line states: "Note 1: Typically, this is 1/5 of the peak output power. Apply sufficient cooling."

So company (A) builds this amplifier and realizes that the only way it passes FTC test is at 100 watts. So they advertise the amplifier as a 100 watt device.

Company (B) builds an amplifier that has max power of 100 watts. Its power supply voltage and current do not allow more power than 100 watts. Indeed, it will shut down if you ask it to go above that. Such an amplifier will be cheaper to build than (A), all else being equal due to lower currents and voltages involved.

The FTC wants the consumer to look at these two amplifiers as being equivalent. Is this good for the consumer?

Show me ONE NC500 based amplifier being sold and advertised as a 100W continuous rating.

 

[Andysu]

If you're putting it to a vote, I vote for more speakers. Perhaps a thread for such a vote?

more speakers sounds like you want to go into the black speaker hole lower pressure octaves that have you going , yee'ha , , more speakers

 

[Old_School_Brad]

Infeon Merus passed the EMC test with MA12070 (used in SMSL A100) reference board with 10cm speaker wires

View attachment 412526

https://www.infineon.com/dgdl/Infineon-UserManual_ClassD_audio_MA120xxx_reference_boards-ApplicationNotes-v01_01-EN.pdf?fileId=5546d46269bda8df0169da3392a743bd

(page 19-23)

SMSL A100 uses no special EMI filtering, except for ceramic capacitors - PCB and 12070 going directly to L-, L+, R-, R+. There is also no inductor between the board connector and binding posts. And the measured rectangular output impulses with Tr < 50ns are a technical proof that cannot be questioned.

View attachment 412529

TI produces similar filterless class D range TPA31XX that I tested a year ago. And below are their notes on FCC test and recommendations on EMC measures.

View attachment 412531

Testing with a 10 cm speaker cable and twisted speaker wires is an intriguing and thoughtful workaround to comply. If this are the methods actually used for compliance with emission limits, I'd say that FTC regulations are considerably more thorough and clear by comparison.

 

[pma]

Yeah. And as it happens only with those cheap filterless solutions that throw full scale switching amplitude to the speaker, the cure would be simple, just add the appropriate output filter. The LC filter has 2 disadvantages:

1) FR depends on load
2) 19+20kHz IMD is worse due to core nonlinearity

However, the EMI issue is IMO much worse than the 2 issues above.

 

[restorer-john]

It is a race to build superb fidelity the likes of which we have never seen. That you feel left behind is no concern of mine.

Oh Please! You're actually in dreamland aren't you? I'm starting to think you have actually lost it Amir.

You've unconditionally recommended amplifiers that have failed en-masse and never once accepted or acknowledged your monumental f#ckup.
You've unconditionally recommended amplifiers that overheat, fail and cannot achieve their specified power outputs. Thumbs up for that!

Not only that, you refuse to test them against their advertised, rated specifications in accordance with requirements of the country you live in. Haha.

Just do it. Or we can. Actually it'll be fun...

"superb fidelity the likes of which we have never seen" What a hilarious joke. Who cares if it shuts down, burns out, overheats, or simply doesn't work?

 

[SIY]

You've unconditionally recommended amplifiers that have failed en-masse

Can you be specific? Which ones and where's the data?

 

[jamesdyson]

How many people here have amplifiers that are either shutting down or have died due to getting too hot?

Great thread, I'm going through buckets of popcorn.Seems to me that the FTC test tells you nothing useful. Whats the use of knowing that an amp can run for 5 minutes at full power on a sine wave when there is no music that will ever get it near that dissipation? It's not helping the consumer.

 

[tmtomh]

Oh Please! You're actually in dreamland aren't you? I'm starting to think you have actually lost it Amir.

You've unconditionally recommended amplifiers that have failed en-masse and never once accepted or acknowledged your monumental f#ckup.
You've unconditionally recommended amplifiers that overheat, fail and cannot achieve their specified power outputs. Thumbs up for that!

Not only that, you refuse to test them against their advertised, rated specifications in accordance with requirements of the country you live in. Haha.

Just do it. Or we can. Actually it'll be fun...

"superb fidelity the likes of which we have never seen" What a hilarious joke. Who cares if it shuts down, burns out, overheats, or simply doesn't work?

Can you be specific? Which ones and where's the data?

This is not the first time @restorer-john has been asked in this thread to be specific about the above-bolded claim. And still no accountability from you, John.

So for the third time, John, which amplifiers has @amirm "consistently" recommended that "have failed en-masse"? Consistently and en-masse means there have been a series of amplifier models - at least two, and given the meaning of "consistently" I would say the clear connotation is at least three. And"en masse" means numerous reports of failure.

So there is:

1. Topping PA5

What are the others?

And bonus question: what reason do you have to believe that the 5-minute FTC test of the PA5 would have enabled Amir to witness the thermal failure that occurred for many users after weeks or months because of the potted components?

 

[pma]

Can you be specific? Which ones and where's the data?

Poll for Topping PA5 owners only please.

Poll for PA5 owners to report product defects. Discussion for any solutions. I think it would be useful to get a handle on some numbers to estimate just how wide spread the issues are. Addendum: Here is Topping's response to the PA5 issues...

www.audiosciencereview.com

 

[SIY]

So there is:

1. Topping PA5

And we don't know what the failure rate is beyond a vague statement from Topping. It might be "en masse" but it might be "more than we'd like but not endemic." I have no idea and I don't know that John does, either.

 

[tmtomh]

And we don't know what the failure rate is beyond a vague statement from Topping. It might be "en masse" but it might be "more than we'd like but not endemic." I have no idea and I don't know that John does, either.

@restorer-john doesn't know - and he'll never admit it.

 

[pma]

And bonus question: what reason do you have to believe that the 5-minute FTC test of the PA5 would have enabled Amir to witness the thermal failure that occurred for many users after weeks or months because of the potted components?

Most probably, it would. Based on what? Not on forum debates, but on my own professional experience, testing of components and whole big systems like military complex system in thermal chambers in temperature range -50C/+50C. It is just the issue you pointed to that thermal cycling is able to discover and the pre-conditioning and rated power long term test are good possible options.