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Amplifier Modules and PCBs For Sale

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stef1777

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Joined 2004
github.com/stefaweb/Q17-Amplifier
I love 230vAC (not DC). It puts the ideas in perspective. ;)

New picture.
 

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454Casull

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Joined 2004
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stef1777

Member
Joined 2004
github.com/stefaweb/Q17-Amplifier
454Casull said:
What's the thing on the top-right, is that a volume control for later?
Click to expand...

A 100K pot. This is a used enclosure box from an old project. I will not use the the pot with the TPA3255 board.

I disabled the PFFB circuit. At first listening, better headroom and natural voice. It's easy to heard as I'm using full range speakers.

It’s weird. The PFFB shouldn't cause such a big difference in sound.

Stéphane
 
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turion64

turion64

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Joined 2019
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stef1777 said:
I disabled the PFFB circuit. At first listening, better headroom and natural voice. It's easy to heard as I'm using full range speakers.

It’s weird. The PFFB shouldn't cause such a big difference in sound.

Stéphane
Click to expand...

Stéphane: A number of us have noticed this with version 1 of the board. I’ve disabled mine as well and the sound reproduction is much more pleasing. Version 2 of the board is addressing this I believe.

Cheers,

Pete
 
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Deleted member 148505

454Casull said:
So you will have the following available within the next 1-2 months (?):

1) TPA3255 module, original (TICore260BTL with new name) but tweaked/improved
2) TPA3255 module, upgraded with split supply
3) TPA3251 module

Or just 2) and 3) moving forward?
Click to expand...

Only number 2 is the priority for now. I made some changes on it that I will apply on 1 and 3 afterwards.

The manufacturing cost went more than x2 compared to Version 1. (I used low TCR 0.1% resistor and C0G caps in some areas) So I removed the ENIG surface finish to lower down the cost.

turion64 said:
Stéphane: A number of us have noticed this with version 1 of the board. I’ve disabled mine as well and the sound reproduction is much more pleasing. Version 2 of the board is addressing this I believe.

Cheers,

Pete
Click to expand...

Sound's like the 2 channels are slightly out of phase that's why the voice is not as full as the non-pffb. I will experiment with it once I receive the new boards.
 
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Deleted member 148505

Tried removing the opamp feedback caps in my TICore260BTL.
Opamps are not heating up (LME49860) so looks stable. Also no faults on open load. I'm using LRS-350-36 PSU which has a 65kHz switching freq.

PFFB: The sound is noticeably better and the vocals are more natural (almost the same as non PFFB)

I'm using ELNA Silmic II all throughout, I soldered them under the board so that I can easily modify the opamp feedback caps.

Maybe a 22pF on opamp buffer feedback cap on my board will suffice for stability.

I need more listening tests to confirm.
 

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