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-   -   Stereo or mono tpa board with low gain (https://www.diyaudio.com/forums/class-d/356759-stereo-mono-tpa-board-low-gain.html)

flo777 2nd July 2020 02:18 AM

Stereo or mono tpa board with low gain
 
Does anyone know of any tpa or similar boards with relatively low gain? 20 to 26 db?
I'd like to use one on my desktop speakers with a small tube preamp.

FauxFrench 2nd July 2020 06:47 AM

Any TPA3116 board can be set to 20dB gain. Better get a board where the heatsink is fixed with screw(s).

flo777 2nd July 2020 01:55 PM

Right, but I was hoping to find a board already set at low gain, since I don't have an iron good enough to desolder such small resistors

jemraid 2nd July 2020 03:53 PM

Hello Flo,

Here's a how to vid,
YouTube
Using an ordinary soldering iron.

And this is the best board to do it on: XH M590 carte amplificateur de puissance numerique tpa3116d2 carte amplificateur audio double 100W haute puissance 12 24V | AliExpress the one that FauxFrench advises

Cheers - Jem

flo777 2nd July 2020 06:16 PM

1 Attachment(s)
Thanks FauxFrench and Jem for the tips.

Actually I already have the xh-m190 v3 tpa3116d2 board, but it has high level of hiss. I read that this is due to high gain.

Table 1 on page 14
https://www.ti.com/lit/ds/symlink/tp...google.ca%252F

I attached a photo of my board. It has R1 of 100k and R2 of 1RD (100k?)
I'm a little confused. Do I just need to remove the R2 resistor to get 20 db gain? What's briefly the difference between the master and slave gain?

jemraid 2nd July 2020 08:26 PM

Hello Flo,

Thanks for the message good of you. Not the two resistors you mention please leave those. Look for these two together 473 (47K) and 753 (75K) you will find two pairs of them one for each amp. Remove the 753 and the hiss will go and the hum will be all but inaudible, and the pops at startup and switch off will go as well.

Thanks to FF my board was the similar but the cure the same.

Cheers - Jem
The master/slave configuration is various combinations of resistors, the chip recognises which is in place.

FauxFrench 2nd July 2020 09:25 PM

flo777, would it be possible that you remove the heatsink, takes of close-up photo of the two TPA3116 ICs and the resistors around? Your board is different from ours. You write that yours is a XH-M190 while ours are XH-M590.

jemraid 2nd July 2020 09:32 PM

Hello Flo,

Just to make sure here's a couple of pics of my board yours will very likely be similar
https://live.staticflickr.com/65535/...ae716fa0_o.jpg

The group of three is duplicated above the highlighted group and these are under my heat sink.

and a close up
https://live.staticflickr.com/65535/...6f676fdc_o.jpg

Hope this helps.

Cheers - Jem

[edit] We had a similar idea at the same time FauxFrench :-)

flo777 2nd July 2020 10:33 PM

2 Attachment(s)
Sure, please see the attached photo.
How can I get the minimum 20db gain (since I'd like to use a preamp with it), and do you think that will also improve the low frequency response along with removing the hiss?
Thanks

FauxFrench 2nd July 2020 11:04 PM

Hi flo777,
On your board, U1 is set as "master" with 26dB gain (100K/20K) and U2 as "slave" with 26dB gain (47K/75K). The two ICs are synchronized.
If you turn the volume potentiometer fully down, do you still have much hiss?


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