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SMSL A100 class D amplifier test
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Old_School_Brad
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Well, that doesn’t really speak either for or against what Pavel has demonstrated.
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- #63
PA3 is filterless?
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(TDA7498)
Amir's measurements show that PA3 is not filter-less.
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You are on wrong amp.
It's Topping Pa3s as I wrote.
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It's Topping Pa3s as I wrote.
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- #65
OK. But how do you know there is no ferrite filter?You are on wrong amp.
It's Topping Pa3s as I wrote.
Topping PA3s Review (Desktop Amplifier)
This is a review and detailed measurements of the Topping PA3s balanced integrated power amplifier. It was sent to me by the company. It is not announced yet and I forgot to ask how much it will cost. It is in similar form factor to PA3 which I reviewed before and that one cost $120. I think...
It is doing at least something, though not much, with shorter speaker wires.
Roland68
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- #68
Ferrites are in SMD, 1nF caps are in SMD. The debate without having the schematics and without further measurements is pointless. Audio band measurements would not tell and are not sufficient in this case.
I have not opened up just going for what people say.
Post #406
Topping PA3s Review (Desktop Amplifier)
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somebodyelse
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They probably did the tests with short cables to a dummy load, getting a pass as the datasheet suggests it can. Some large companies apparently use similar methods to meet the letter of the rules rather than the spirit, especially for cost sensitive items, based on what one EMC test house told a local radio museum when they were having interference problems eventually traced to SMPS in light fixtures and mains outlets with built in USB outlets. The cheap outlets from an obscure manufacturer turned out to emit much less interference.
Yes I follow that thread...
I run my amps with full volume and software control.
Also have some of these boards which I changed the ferrite to BLE32PN300SN1L and it sounds better with them.
Nice amp when you run it balanced in.
- Thread Starter
- #73
The topic here is SMSL-A100, if it has not been noticed yet. Everything else, including behaviour of PA3s, are speculations, not supported by measured results.
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With the additional LC filter, the SMSL-A100 works fine, with quite clean HF spectrum, considering the class D with B-type modulation. However, the manufacturer should have implemented some kind of filtering inside the amp and should have followed Infineon recommendations. Without that, the amp would pass FCC EMI test only with the shortest speaker wires, like 10 cm.
With the filter, even 3m long wires are no issue:
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With the additional LC filter, the SMSL-A100 works fine, with quite clean HF spectrum, considering the class D with B-type modulation. However, the manufacturer should have implemented some kind of filtering inside the amp and should have followed Infineon recommendations. Without that, the amp would pass FCC EMI test only with the shortest speaker wires, like 10 cm.
With the filter, even 3m long wires are no issue:
- Thread Starter
- #74
I am afraid that many readers here have no idea how the output from the "filterless" class D with B-type modulation looks like. To refresh, I am posting the same measurement as in the previous post, now without the additional LC filter. If this amp, with longer speaker wires, is close to the Wi-Fi, the transmission is paralyzed. This is serious.
The problem is the ultrasonic content, extending into the RF bands, that may be inaudible but cause all sorts of other problems. Including in nearby audio components with insufficient RF refection, or the radio tuner in your system. Not including an output filter is surprising to me, and I suspect would not pass consumer EMC tests. Those are huge spikes way up in the AM radio band!
- Thread Starter
- #77
This makes no sense. Do you know what you speak about?
Below detailed study of output in time and frequency domain, up to 10MHz. Click on the thumbnail.
However, it probably makes sense only to those who are able to read the plots.
Old_School_Brad
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deadwood83
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From firsthand experience with wifi and MA12070 (I still run 2x PA3s as biamp for stereo speakers)... signal strength never changes. And since my teardowns of the PA3s PCBs, I have added a wifi video doorbell (Reolink) which has both amps and speakers flanking the transmission path to either side.
My presence in LOS transmission beam does far more than amps on/off/playing. I agree that topping and smsl and all the others do take shortcuts as I called out in both posts linked above.
I see measurements connected to outputs. Where is the single loop antenna at 1, 3, and 10m distance while amp is connected to speakers to support claims it emits compliance-breaking levels of radio power? It is useless to speculate on CFR Title 47 Chapter 1 Subchapter A Part 15 compliance if you do not measure it in the manner specified by the FCC. Which is at 3m, non-contact, single loop antenna.
My presence in LOS transmission beam does far more than amps on/off/playing. I agree that topping and smsl and all the others do take shortcuts as I called out in both posts linked above.
I see measurements connected to outputs. Where is the single loop antenna at 1, 3, and 10m distance while amp is connected to speakers to support claims it emits compliance-breaking levels of radio power? It is useless to speculate on CFR Title 47 Chapter 1 Subchapter A Part 15 compliance if you do not measure it in the manner specified by the FCC. Which is at 3m, non-contact, single loop antenna.
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