Paralleling two TDA7293 with balanced inputs

[pbilous]

Schematics is attached.

Gain of the first stage is 1.1 and gain of the TDA chip is 10.

Any comments are appreciated!

 

[stv]

keep in mind minimum gain per datasheet is 26 (20-fold).
also I am not sure whether it's a good idea to use the TDA in "balanced" mode.
if you want to take advantage of balanced input (hi CMMR) an op-amp may be better suited for balanced-unbalanced conversion.

 

[stv]

hi CMMR

CMRR, of course!

 

[jan.didden]

Why is the 2nd one not driven? Is this a joke?

Jan

 

[stv]

Is this a joke?

No, it follows the datasheet (connection via "B-driver").

 

[jan.didden]

That's interesting! I need to check that out!

Jan

 

[pbilous]

Since the TDA7293 acts as a difference amp, will it multiply the gain by 2 anyway? I ran the same schematics using LM3886 in Tina-TI simulation and output level is at 26 dB

 

[pbilous]

Is it true that 0.1% tolerance resistors should give theoretical CMRR of 66dB, even if used with TDA7293 ?

 

[pbilous]

That's interesting! I need to check that out!

Jan

There is a way to use second TDA7293 in a slave mode while the first one sets the gain.

 

[Michael Chua]

That's interesting! I need to check that out!

Jan

I believe this is what the OP is referring to.
ST calls it Modular.

 

[sesebe]

You can try this: https://www.diyaudio.com/community/...ge-paralel-for-best-sound.184102/post-2894132

 

[pbilous]

You can try this: https://www.diyaudio.com/community/...ge-paralel-for-best-sound.184102/post-2894132

Wow that was in 2012!

I looked at the schematics from the data sheet and it looks pretty involved for that class G implementation. I am little hesitant to use it because of that.

 

[pbilous]

According to the datasheet for TDA7294 min gain allowed is 24 dB. I therefore adjusted resistor values to 1K and 15K