Hello That's it I tested my circuit on a board and it works ! :) I make it with JLCPCB and wait for the final, I made it small as possible for me, I will certainlty adjust some resistors value to be the best as possible for my use. The size of the circuit is: 50.7x35.5mm This is a 3D view:

Hello I'm back with news after searching and buy book about Aop, I hope I found a solution, I searh on other forum but it's not the answer that I want and books help me in that case. So I just finish to build my own circuit and I'll test it, if it's ok I will build It. It will work with an AOP TL072CP and dual power supply. My first try with passive resitor appear to be a solution for some people, but I don"t want that, so I have tested to preserve the crosstalk. I'll keep you informed if anyone is interested

Hello ECHO, I thank you, I've just contacted her. I hope I will have an answer.

This is what I think to made, any advices please? Thanks

Hello, It's a good idea but I'm not sure of the result, crosstalk may be impacted...😕 I need to mount it after the main potentiometer of the A10 amplifier. I don't know if it's good to do that,

Hello Thanks for the answer, finally I put a preamp with rca output for the subwoofer and it works but it is not the best solution for me. I want the minium devices. The subwoofer must have it's volume up or down when I adjuste the main volume of the amp. and the input rca signal musn't have risk to be bridged or mixed that's why I don't want Y rca. I think the "best" solution is to put an aop after the main potentiometer and catch the signal to bridge mix it and send it to the output rca subwoofer. This avoid the risk to use only one channel for the bass....but this needs a power supply and it's not great or maybe a solution is possible with the preamp tube? the tweak of the A12 use only one side of each preamp tube, perhaps it's possible to make something and catch a signal and send it to the mono output rca subwoofer ? if it's possible the signal must not be bridged or mixed at any time it's a crucial point for me. I hope you could help me please? I thank you.

Hello, Thanks but it's not that I Want I prefer a solution built inside the amp who can catch the signal from input rca and send it to the ouput rca subwoofer. but maybe a solution with capacitors and resistors wil be good ? or with and AOP ? this avoid the problem of "bridge" the signal at the rca input ! I'm searching for a good solution...