Which TPA3255 amp do you recommend?

[Bruce Morgen]

Thanks for the photo. Is that the innards of the most recent version or the old one with the popping issue?

FWIW, I think I might be better off with 50V Nichicons, which tend to be conservatively rated, than with random 63V "Chinesium" caps -- just a thought...

 

[3eaudio]

Some members of the diyaudio forum made a tpa3255 based off the TI EVM to optimize noise and THD performance. I missed out on the group buy for a pre-assembled board so I bought a PCB and hand soldered it. This is a upgraded version of the board that maty posted in post #7 (now includes post filter feedback). It actually beat the TI spec at 0.0011%THD vs the TI specified 0.0021%THD with PFFB enabled
https://www.diyaudio.com/forums/group-buys/340880-tpa3255-reference-design-class-amp-gb.html

we should also look at the THD+N,be note that some test are use 10ohm load not a 4ohm specified from Ti.
if xrk971 can provide a sweep curve with PFFB and without PFFB that will more clear to others.

• 1W - 3.16V/10ohm:THD+N=0.0097%
• 10W -10V/10ohm:THD+N=0.0035%
• 20W -8.19V/3.3ohm:THD+N=0.0061%

how much improvement form there compare to our board without PFFB?

 

[Streamc]

How do Aiyima compared to reference TPA3255 Eval Board? I have Aiyima. It sounds good dynamically but deaf.
I use it with Meanwell LRS 48V 350 Power.

 

[Bruce Morgen]

How do Aiyima compared to reference TPA3255 Eval Board? I have Aiyima. It sounds good dynamically but deaf.
I use it with Meanwell LRS 48V 350 Power.

What to you mean by "deaf?" Just curious...

 

[Streamc]

What to you mean by "deaf?" Just curious...

High frequencies are not so clear as it may be.

 

[Bruce Morgen]

High frequencies are not so clear as it may be.

Thanks. I always question such observations myself, because in my experience a statement like "High frequencies are not so clear as it may be" can actually mean "High frequencies are not as prominent as I prefer" -- but of course the listening experience always comes down to what we enjoy.

 

[Bruce Morgen]

Both amps have the same output IC and the same op amp chips, so offhand I'd venture they sound more similar than different and the differences would have to be pretty subtle and related to stuff like inductor and capacitor values and/or quality. The EVM board certainly has features that no equipment manufacturer of sound mind would bother incorporating, but the resulting reduced PCB size, complexity, and parts count probably wouldn't impact performance enough to hear.

 

[Streamc]

High frequencies are not as prominent as I prefer

This is different statements because I would not prefer high frequencies on TPA3116 but they are very clear
in contrast with TPA3255. Anyway all is subjective.
Did you heard them both?
Thanks.

 

[carlmart]

What are the main differences between the Aiyima, the 3e and the XRK schematics?

Aiyima is using the chip manufacturers' schematic?

The 3e, according to their manual, are adding more parts and changing others?

Where do I find XRK's schematics?

 

[Bruce Morgen]

This is different statements because I would not prefer high frequencies on TPA3116 but they are very clear
in contrast with TPA3255. Anyway all is subjective.
Did you heard them both?
Thanks.

I have a TPA3116 2.1 "chip amp" that I use for TV sound and the TPA3255 power amp for serious music listening. To my ear, they both perfectly suitable for their (quite different) jobs. Of course very different speakers are involved, so it's hard to compare them usefully. I have not heard the EVM, but have studied its documentation as well as the TPA3255 data sheet.

 

[carlmart]

Where do I find XRK's schematics?

OK, I did find XRK's schematics, and they are really very complicated, certainly more than the other two.

Wasn't aware there was an Evaluation Board two available, which is certainly a good thing, costing $178. That price would certainly make the XRK a better option, considering comments from those that used it.

Of course, to the EVM and the XRK you have to add a good power 53v/3A supply, not sure what the cost.

Now, I would consider all these DIY projects, so I wonder how do they compare with a good discrete DIY power amp. THDs would be lower, even more at clipping, where all class-Ds show awful results.

 

[nrabbit]

we should also look at the THD+N,be note that some test are use 10ohm load not a 4ohm specified from Ti.
if xrk971 can provide a sweep curve with PFFB and without PFFB that will more clear to others.

• 1W - 3.16V/10ohm:THD+N=0.0097%
• 10W -10V/10ohm:THD+N=0.0035%
• 20W -8.19V/3.3ohm:THD+N=0.0061%

how much improvement form there compare to our board without PFFB?

View attachment 79105

See post #7 from maty in this thread. That was a pre-PFFB early testing board. That was at 6 ohms, .01 THD + N. I think a later sample hit .007% THD + N without PFFB enabled in to 3.3 ohms.

I noticed that you guys cite THD+N < 0.01%, 0.3W – 200W, 4Ω but your AP THD graph shows hitting .02% THD at 50w. I believe as far as US industry standards (FTC) the proper advertising would be:

THD less than X% for any power from 250mW to Rated Power over the bandwidth (min) of 20Hz-20Khz.

 

[somebodyelse]

Can't those caps be upgraded to something better and larger? Space is an issue, though.

Probably - but you then need to check the regulator that feeds the opamps - they're often not rated to the full voltage either.

 

[Bruce Morgen]

OK, I did find XRK's schematics, and they are really very complicated, certainly more than the other two.

Wasn't aware there was an Evaluation Board two available, which is certainly a good thing, costing $178. That price would certainly make the XRK a better option, considering comments from those that used it.

Of course, to the EVM and the XRK you have to add a good power 53v/3A supply, not sure what the cost.

Now, I would consider all these DIY projects, so I wonder how do they compare with a good discrete DIY power amp. THDs would be lower, even more at clipping, where all class-Ds show awful results.

The solution to bad results at or past clipping is simple: select an amp powerful enough for your speakers and listening habits, regardless of the technology or ccomponents involved. Easy, no?

 

[carlmart]

Where do I find XRK's schematics?

OK, I did find XRK's schematics, and they are really very complicated, certainly more than the other two.

Wasn't aware there was an Evaluation Board two available, which is certainly a good thing, costing $178. That price would certainly make the XRK a better option, considering comments from those that used it.

Of course, to the EVM and the XRK you have to add a good power 53v/3A supply, not sure what the cost.

Now, I would consider all these DIY projects, so I wonder how do they compare with a good discrete DIY power amp. THDs would be lower, even more at clipping, where all class-Ds show awful results.

 

[carlmart]

The solution to bad results at or past clipping is simple: select an amp powerful enough for your speakers and listening habits, regardless of the technology or ccomponents involved. Easy, no?

Well, that is obvious. I have been an audio professional for film & video for more than 50 years, so I do know the relationship between amps and speakers. But I do not like the way Class D amps clip.

 

[robertospeed]

But isn't there a way to remove the noise when I turn the TPA3255 on and off?

 

[Bruce Morgen]

But isn't there a way to remove the noise when I turn the TPA3255 on and off?

There are external solutions for that -- look up "UPC1237 speaker Protection Board." Even if the board you choose claims to be "two-channel," it's best to get two -- one for each channel -- to avoid problems caused by the "-" or black amp terminal not being connected to the chassis ground of most (all?) "chip amps." It's a somewhat awkward way to avoid the problem, but it's inexpensive and it works.

 

[robertospeed]

There are external solutions for that -- look up "UPC1237 speaker Protection Board." Even if the board you choose claims to be "two-channel," it's best to get two -- one for each channel -- to avoid problems caused by the "-" or black amp terminal not being connected to the chassis ground of most (all?) "chip amps." It's a somewhat awkward way to avoid the problem, but it's inexpensive and it works.

It's not for me to do these things, I don't understand anything, but isn't there something easier?

 

[Toku]

It's not for me to do these things, I don't understand anything, but isn't there something easier?

Give up on improving your current amp and buy a new TPA3255 amp with no pop noise. I do so because it is so cheap.