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AIYIMA A07 TPA3255 Tear Down

pma said:
Probably not. More here:
https://www.audiosciencereview.com/...5-amplifier-measurements-lm4562-option.19155/

More important than the opamp swapping is the power supply used, as you can see from the measurements in the linked thread.
Click to expand...
I just caught your thread and read through. Nice to see the power noise reduced but I agree, ~1 dB improvement is not going to rock the boat too much. Again, thanks for the deep dive. Very cool to see some investigation happening on budget equipment with socketed components.
 
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I really wish someone would make a version of one of these TI chip amps without the volume control, which is invariably a cheap part that degrades the sound. And with a decent power supply. Something like the discontinued basic Allo Volt.
 
RigorDude said:
I really wish someone would make a version of one of these TI chip amps without the volume control, which is invariably a cheap part that degrades the sound. And with a decent power supply. Something like the discontinued basic Allo Volt.
Click to expand...

Although I question your presumption -- "a cheap part" my be deficient in "feel," long-term reliability, and/or taper matching between sections, but as long as it's properly functional it won't color "the sound" -- TI's own TPA3255EVM and a number of Chinese-made boards fit that description. As for assembled, ready-to-use TPA3255 power amps, how much are you willing to spend for your preference?

Finished HIFI TPA3255 Class D Power amplifier BTL High Power amp
 
There were at least two versions of this A07 amplifier as the earlier version did not have Pop Suppression. I have the earlier version !

After reading all these reviews about the A07 I can’t help thinking that there is little point in having the TPA3255 in this model and the A04 with the TPA3251 is actually the better option in every respect. You can’t run the TPA3255 to anywhere near its capacity because of the tiny heat sink !! The higher voltage of operation does not provide any advantages as you can’t use the power that this would otherwise provide.

The A04 runs at a lower voltage (typically up to 32 volts) so better components can be used (higher value Power Supply Capacitors).

So I would avoid the A07 TPA3255 model and concentrate on the A04 TPA3251 model as this seems to be a better balanced solution and many of us think it sounds better.

I am also a fan of the OPA1656 in these amplifiers. Although I believe the original Op Amps to be genuine, the OPA1656 does seem to make a positive difference.
 
Bushellj said:
There were at least two versions of this A07 amplifier as the earlier version did not have Pop Suppression. I have the earlier version !

After reading all these reviews about the A07 I can’t help thinking that there is little point in having the TPA3255 in this model and the A04 with the TPA3251 is actually the better option in every respect. You can’t run the TPA3255 to anywhere near its capacity because of the tiny heat sink !! The higher voltage of operation does not provide any advantages as you can’t use the power that this would otherwise provide.

The A04 runs at a lower voltage (typically up to 32 volts) so better components can be used (higher value Power Supply Capacitors).

So I would avoid the A07 TPA3255 model and concentrate on the A04 TPA3251 model as this seems to be a better balanced solution and many of us think it sounds better.
Click to expand...

Those two amps cost within a few $ USD of each other, and if you're worried about heat -- which has been no problem here, even at borderline-deafening volumes -- you can run your A07 at lower voltage. Want more filter capacitance? Easily added at the SMPS output or the A07's power connector, no disassembly required. I'd rather have the A07's considerable extra headroom @ 48VDC for brief -- too brief to overheat anything, so in this way you certainly can safely "use the power"-- musical peaks provided by its TPA3255 than go by vague subjective statements like "many of us think it sounds better." I like my two A07s so much that I just ordered two more -- for less than $100 USD shipped, including sales tax. They more than stack up to the SAE and Adcom "audiophile" gear I swore by for decades -- for peanuts!
 
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” Want more filter capacitance? Easily added at the SMPS output or the A07's power connector, no disassembly required”

Bruce can you elaborate on this, please?
 
TheWalkman said:
” Want more filter capacitance? Easily added at the SMPS output or the A07's power connector, no disassembly required”

Bruce can you elaborate on this, please?
Click to expand...

You can just connect an additional electrolytic capacitor in shunt across the DC connection between the PSU and the amp, being careful to match polarities ("+" and "-"). If you're using a "power brick," this would require some butchery, but it's easy-peasy if you're powering the amp via an industrial SMPS with the usual multiple DC output terminals. This works because paralleled capacitance is additive, e.g. two 1000 mFd capacitors in parallel total 2000 mFd.

Disclaimer: Don't do this sort of stuff unless you're confident and experienced working with electricity -- this sort of tinkering is not CE or UL (or whatever) approved!
 
Bruce Morgen said:
You can just connect an additional electrolytic capacitor in shunt across the DC connection between the PSU and the amp, being careful to match polarities ("+" and "-"). If you're using a "power brick," this would require some butchery, but it's easy-peasy if you're powering the amp via an industrial SMPS with the usual multiple DC output terminals. This works because paralleled capacitance is additive, e.g. two 1000 mFd capacitors in parallel total 2000 mFd.
Click to expand...
Adding more capacitance increases the surge current that the external power supply has to provide. This may cause problems for it (power supply). As is, there is a pretty good sized spark when you plug in the power supply. I wouldn't push it further. :)
 
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amirm said:
Adding more capacitance increases the surge current that the external power supply has to provide. This may cause problems for it (power supply). As is, there is a pretty good sized spark when you plug in the power supply. I wouldn't push it further. :)
Click to expand...

Yes, the idea to add 2000 uF might be dangerous (and not HF efficient). Much less capacitance is recommended by manufacturers to reduce HF ripple, see (2) below.

1610869593351.png
 
Thank for the advice, gents! :cool:

Sorry to inject a little actual, long-term music listening user experience with the products under discussion, but no such problems have emerged here -- not even a hint. BTW, I never unplug my A07s with the DC on and don't even use their front panel power switches -- my entire system turns on and shuts down via the switch on a breaker-equipped, appropriately-rated AC power strip.
 
pma said:
Yes, the idea to add 2000 uF might be dangerous (and not HF efficient). Much less capacitance is recommended by manufacturers to reduce HF ripple, see (2) below.

View attachment 106600
Click to expand...

"(2) below" is irrelevant -- it describes the circuit used to perform a "ripple & noise" measurement on the product in question and does not indicate anything about the effect of or any recommended limit on additional shunt capacitance. Amir's comment correctly pointed out a potential/theoretical peril that may -- or may not -- be problematic in some applications, but AFAICT isn't in this particular case.
 
Bruce Morgen said:
No. When you look past the fancy features, you'll find it uses a much older and less capable Class D output chip, the TAS5532A. The A07's TPA3255 is a much better performer.
Click to expand...

Thanks, appreciate tha answer, almost pulled the trigger on the A07 because of the digital input! Guess I'm waiting for the Loxjie D30 to be in stock.
 
Bruce Morgen said:
Although I question your presumption -- "a cheap part" my be deficient in "feel," long-term reliability, and/or taper matching between sections, but as long as it's properly functional it won't color "the sound" -- TI's own TPA3255EVM and a number of Chinese-made boards fit that description. As for assembled, ready-to-use TPA3255 power amps, how much are you willing to spend for your preference?

Finished HIFI TPA3255 Class D Power amplifier BTL High Power amp
Click to expand...
Thanks - very helpful. I think it’s best, in general, to have fewer potentiometers in the signal chain - just one if possible. I haven’t seen a board without a pot but maybe I’m not looking in the right place.

I had a two channel TPA3116 board that sounded really nice with a ham radio power supply. My recollection is that the board cost about $25 on eBay. The power supply might have been 100 bucks. Given that, it seems to me that something solidly engineered (like the AliExpress item) should be doable for $250, if not less. I will look into the TI EVM.
 
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Why would something that uses the same chip be able to output 300 watts per channel? Guessing it's peak and not RMS, but I do like the internal power supply and thinking about buying one. Just stinks there is no subwoofer out, or higher power cheap amps reviewed yet.

1620336293280.png
 
They all say that. That is the theoretical maximum they could output.
Note: There is now an option for with or without power supply.

Screen Shot 2021-05-06 at 14.30.42.png
 
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