I've measured a black TPA3255 a few weeks back and it has some stability issues at higher voltages. Not sure if blue has the issue too. It appears to be a 15V DCDC converter (LM2575) in the upper left of the board. Hit it with cold spray and you'll see the spectrum shift and clean up.
The first plot below is TI reference design. Noise floor is measured at 91uV, TI spec is 80uV. The second is black PCB design from Amazon. Noise is almost 4X higher. Note the noise at 1K is 10 dB higher than TI reference design.
So, yes, the supply of the no-name TPA3255 is plentiful and cheap, but the performance isn't anywhere near the TI reference design. Still, it's a lot of bang for the buck.
Quick Look: A Generic TPA3255 Design
– QuantAsylum
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Yes, good point, you are correct I should have noted.
I've attached the 1W measurements on each. On the clone you see -21.5 dBV in gives 6.45 dB out (28 dB gain).
On the TI you see -21.4 dBV in gives 5.96 dBV out (27.36 dB gain).
So, that's about 7% linear gain difference, which doesn't come close to explaining the noise discrepancy. The clone has left a lot on the table compared to what TI was able to achieve.
PS. I also attached the clone at 300W @ 50V. A little more rail here would have helped a lot. TI specs 315W and 51V and 10%. So, the clone is doing just fine on max power. This is a killer part TI has produced.
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IMHO, there's a reason TPA3221 was made. Apart from lower cost and BOM with integrated LDO , bootstrap and single ended input.
It actually eliminate the possibility of clone manufacturer from using low quality parts that will affect the final results.
That chances of cheap and cheerful TPA3221 clones being as good as TI reference is easier to meet
TPA3255 will be reserved/remain for medium/high cost amplifier
Well, the TPA3221 is a decade behind the TPA325X in THD but will highly benefit from PFFB implementation.
I'm actually into a pcb for the TPA3221 with smaller heatsinks and some Codaca dual-inductors + PFFB (compared the the TPA3255 approach).
Regarding SE input for the TPA3221, i suspect that a dedicated AFE is better than the internal stage (beside the fact that it is needed for PFFB to get some more gain) with this chip as well. (From our tests/experience with TPA3128/TPA3118 and PFFB - mainly all TI chips do much better when driven fully differential.)
I'm actually into a pcb for the TPA3221 with smaller heatsinks and some Codaca dual-inductors + PFFB (compared the the TPA3255 approach).
Regarding SE input for the TPA3221, i suspect that a dedicated AFE is better than the internal stage (beside the fact that it is needed for PFFB to get some more gain) with this chip as well. (From our tests/experience with TPA3128/TPA3118 and PFFB - mainly all TI chips do much better when driven fully differential.)
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Gentlemen,
I received a mail from Texas about the 50% rebate for their EVM. Since I read the first communication about this TPA3255 years ago, with this price I decided to go for it.
Because on other projects I use batteries, I am thinking to use 50.4V 20A battery to power the unit.
With a huge capacity on the battery (able to 10C in continuous = 200A and 20C for few seconds) I imagine it will be ok for the EVM.
In this thread I've read you use mainly power unit from plug to power it. Do you think battery is a good way to power the EVM?
I received a mail from Texas about the 50% rebate for their EVM. Since I read the first communication about this TPA3255 years ago, with this price I decided to go for it.
Because on other projects I use batteries, I am thinking to use 50.4V 20A battery to power the unit.
With a huge capacity on the battery (able to 10C in continuous = 200A and 20C for few seconds) I imagine it will be ok for the EVM.
In this thread I've read you use mainly power unit from plug to power it. Do you think battery is a good way to power the EVM?
Well, I do not know exactly, I have to check if it is AC batt or DC batt... 
Well well, batteries have voltage dropping down under discharge. With big capacity I hope under home listening conditions voltage will stay the same.
Thanks good doctor for your answer and also thank you DPH.
I've tested batteries with a little class D amp with excellent results in subjective terms of audio quality, I am impatient to test the EVM and batteries.
Well well, batteries have voltage dropping down under discharge. With big capacity I hope under home listening conditions voltage will stay the same.
Thanks good doctor for your answer and also thank you DPH.
I've tested batteries with a little class D amp with excellent results in subjective terms of audio quality, I am impatient to test the EVM and batteries.
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I like the idea of batteries myself, and I a converted 18V Makita drill battery(+-14.8V) for my phono preamp.(I hope to only charge it once a year). But I think you need a very low resistance battery for the tpa3255 to avoid massive voltage drop! I hope your battery is a lipo with a really good C rating, or else a mediocre psu will be better at high loads. I have often been surprised by the voltage drops from a 100Ah car lead battery delivering 5-600W. Would be interesting if you could do a comparison with battery vs pwm power supply!
