NEW Nvarcher TPA3255 Mono Module with Flat Inductors. Measurements inside. $35

[Roland68]

The question we can ask ourselves is: what is the default gain if we attack the module directly?

We could use a buffer of this type if needed:

View attachment 507408

This is the same cheap dual-op-amp solution found on many TPA3255 boards.

For something of higher quality, XRK Audio on Etsy offers, among other things, the BTSB buffer.

 

[daniboun]

This is the same cheap dual-op-amp solution found on many TPA3255 boards.

For something of higher quality, XRK Audio on Etsy offers, among other things, the BTSB buffer.

You have plenty of options. But it's consistent with the price of the modules; if I start by buying a Neurochrome Buffer, for example, I end up buying four modules for the price of the Buffer alone, lol --)))

Universal Buffer

Fully differential buffer which provides a differential (balanced) and a single-ended (unbalanced) output with extremely low distortion. Great building block for a DIY preamp.

neurochrome.com

 

[KL....]

You have plenty of options. But it's consistent with the price of the modules; if I start by buying a Neurochrome Buffer, for example, I end up buying four modules for the price of the Buffer alone, lol --)))

Universal Buffer

Fully differential buffer which provides a differential (balanced) and a single-ended (unbalanced) output with extremely low distortion. Great building block for a DIY preamp.

neurochrome.com

Thank you, @daniboun, Yes, Neurochrome Universal Buffer achieving -140dBc (0.00001%) THD although (not small) additional cost, is it, but very impressive?

 

[dansan69]

An input buffer might not be needed if your source has XLR outputs and your source can provide 4v output.
The PBTL configuration listed in the TI documentation suggests 10uF at input A and input B, not sure that this is provided on this board.
The input impedance is typically 20kOhm in PTBL configuration and the gain is 21.5dB.

 

[daniboun]

An input buffer might not be needed if your source has XLR outputs and your source can provide 4v output.
The PBTL configuration listed in the TI documentation suggests 10uF at input A and input B, not sure that this is provided on this board.
The input impedance is typically 20kOhm in PTBL configuration and the gain is 21.5dB.

This assumes that the module complies with official TI recommendations.

 

[daniboun]

Thank you, @daniboun, Yes, Neurochrome Universal Buffer achieving -140dBc (0.00001%) THD although (not small) additional cost, is it, but very impressive?
View attachment 507455

Neurochrome is the cream of the crop. This buffer deserves better than $35 modules lol

 

[dansan69]

This assumes that the module complies with official TI recommendations.

The 20kOhm input impedance is a TPA3255 number, so not specific to the implementation.

The board vendor lists Magnification factor: 11.98x, this matches the quoted gain of 21.571dB (one of the measurements graphs show this)
The frequency response shows a high pass response with a roll off below 10Hz, this could suggest a DC blocking cap at the input, but could also be a measurement artifact.

Do you have a way of verifying if a dc blocking cap is present at the input?

 

[daniboun]

The frequency response shows a high pass response with a roll off below 10Hz, this could suggest a DC blocking cap at the input, but could also be a measurement artifact.

Do you have a way of verifying if a dc blocking cap is present at the input?

I can ask the seller unless we can identify it from a picture...
Regarding the input gain, I hope we can trust the measurements.

 

[Roland68]

Amigos got the answer

"No OP amps on this module"

I can ask the seller unless we can identify it from a picture...
Regarding the input gain, I hope we can trust the measurements.

But if there is no op-amp on the board, where should the input gain come from?

 

[dansan69]

In the TPA3255 datasheet TI lists a gain of 21.5 dB this is without any external OP amp, this matches what the board vendor is listing for his implementation.

 

[audiodesignguide]

tested, heatsink very little, input capacitors not good, it sound much worse than Sylphaudio modules in a direct comparison

 

[Roland68]

tested, heatsink very little, input capacitors not good, it sound much worse than Sylphaudio modules in a direct comparison

Could you please post a picture without the heatsink?

 

[Nolperi]

The filter has 15uH coils suggesting this is OK for a 8 ohm load. I wouldnt run high voltage on this tiny thing either.
Balanced input is the way to go. I think it would take single-ended as well, with DC block capacitors. 1uF MKT capatitors are fine in my opinion. Low frequency attenuation should not be a problem as clearly this board is not for subwoofing