TDA7294 balanced input

[Orgonom]

Hi,

is it possible to add an balanced input to a classical
TDA7294 design?
I´m using boards from xy Audio, ver 1.1.

I thougt that i´ve to add only a Resistor to the inv. Input.

Maybe some of you can help.

Thanx in advance,
Andreas

[Osvaldo de Banfield]

Yes, it is possible. In the circuit attached, remove the ground side of R3 from ground, and put there the inverted input, but a balance in the circuit must be performed for properly job, put a 330nF (or other value in this line also as in the NI input, and the same 680R in series to the input), so maintain the input balance between line signals.

As this changes varies the amplification factor, perhaps oscillations can get, in such a case, re-calculate for more closed loop gain.

Good luck!

[bobodioulasso]

What happens if nothing plugged into the input?
I think inverting input needs a resistor to ground. 22K?

[Osvaldo de Banfield]

Originally Posted by bobodioulasso

What happens if nothing plugged into the input?
I think inverting input needs a resistor to ground. 22K?

Only in the + input, the - input 22K goes to the output, as in the circuit above.

If no input, in such case, the amp is balanced, and no output will be.

[bobodioulasso]

You are right. Thx

[Osvaldo de Banfield]

Which part of Europe are you from? My brother is living in Madrid from 2002.

[bobodioulasso]

I am in France.

[Osvaldo de Banfield]

OK. Good luck!.

[Orgonom]

Thanx Oswaldo,

will try it this weekend.
And report.

Andreas