@daniboun - by the way I bought the Topping, and built two monoblocks from Sylph and two monoblocks from 3E audio (TPA3255) and both of the TPA3255 versions sound way better than the Topping. The distortion measurements do not measure transparency and tonal quality well. Only listening can discern the better amp.
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3E Audio 260-2-29A : TPA3255 / HA3588 CoilCraft / PFFB Fully differential.
- Thread starter daniboun
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antcollinet
Grand Contributor
Allow me to clarify, or restate that:
Listening can only discern the better amp if it is done controlled, and blind. Otherwise you are just listening to what your subconscious brain does with the sound, and not the actual sound waves reaching your ears.
and of course the most important aspect of the controlled set up for A-B testing: you must level match the 2 amps to at least .25db
Thomasel84
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I am trying to finish a build around 260-2-29A board. Connected everything as supposed but the board does not seem to work. I have power to the board (36v) but the power led doesnt turn on and the amp is silent. Am I missing something here or there is a chance I delivered a bad board. The ps is a Mornsun lof350-20b36
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The output from the amp is differential. Each voltage swings about the halfway point of your power supply. It looks like you may have grounded your speaker terminal on the box. The outputs have to be completely isolated from anything.
Not when the difference is that obvious. The TPA is transparent, the Topping is not. It's plain to hear. No blind testing is needed. Try them both and see what I'm talking about.
You need something like this:
Notice the insulators that will keep each connector separated from the case (if you drill the right diameter hole).
Thomasel84
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The speaker output binding posts are completely isolated from the chassis with internal plastic washers and the ps output has little tolerence from case but it has a plastic sheet in between. All the connections are checked for shorts with multimeter too
Edit: Problem solved. There was an issue with the power suply voltage adjustment. Thank you
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antcollinet
Grand Contributor
That is what they all say. Biases (as well as lack of controls such as accurate level match) can create "obvious' differences. And the measurements can discern transparency far better than any human ears. It is why blind testing exists.
Still - you've been here long enough to understand the topic. If you are still not willing to embrace the way science actually works, or at least engage with it, I'm sure I'm not going to convince you now.
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@Thomasel84 can you try adjust SMPS voltage above 36V like 37V or 38V? i believe the LOF350 can adjust higher a little bit.
OP
daniboun
Major Contributor
- Thread Starter
- #654
I agree with @antcollinet
All of these amps have identical transparency levels. Don't trust your ears but the measurements and that's precisely why measurements exist.
due to the PFFB so there is a certain voltage for op-amp, can't lower to 18VNice to read this )
It's super strange though since the TPA3255 chip has a voltage range from 18V to 51V.....
Thomasel84
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It seems the voltage from the ps should be adjusted at about 38Vdc. This is my first build around a class D amp (i build several tube stuff before) and I really like this chipset so far. It sounds just like it measures, it has excellent efficiency (unlike tube amps) and it comes at a reasonably cost. The 3e Audio 260-2-29A board is excellent quality and I admire the support 3eaudio provides even in the forums. I want to thank all other members too and especially Daniboun for all the information around these builds. This is what makes the community and DIY hobby nice and enjoyful!
Hi,
So I had read all this forum for create my amp too. I wanted too have SE but I don't' have the capacity too do this, so I will make a non stereo amp, that mean than I will cannot use a stereo song but I will use the left and the right. Isn't clear but look the picture of my schema and u will understand, I hope.
Can you say too me if my plan is good ?
I will wait your response, thanks you so much for read me
Jérémy Salinas
So I had read all this forum for create my amp too. I wanted too have SE but I don't' have the capacity too do this, so I will make a non stereo amp, that mean than I will cannot use a stereo song but I will use the left and the right. Isn't clear but look the picture of my schema and u will understand, I hope.
Can you say too me if my plan is good ?
I will wait your response, thanks you so much for read me
Jérémy Salinas
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daniboun
Major Contributor
- Thread Starter
- #659
I'm not sure I understand... a balanced input remains a balanced input. If we understand that you want to take advantage of differential inputs using an RCA>XLR adapter, I do not recommend it at the risk of degrading the signal and impacting the gain of the module.Hi,
So I had read all this forum for create my amp too. I wanted too have SE but I don't' have the capacity too do this, so I will make a non stereo amp, that mean than I will cannot use a stereo song but I will use the left and the right. Isn't clear but look the picture of my schema and u will understand, I hope.
Can you say too me if my plan is good ?
I will wait your response, thanks you so much for read me
Jérémy Salinas
As long as I understand your problem: I suspect that your concern is to have two RCA inputs? If you are in France, you can ask any electronics store to solder you a pair of OPA1656 or 1612 to benefit from SE mode. It shouldn't cost you much)
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