You will have to bear with me............... I haven't done this for 60 years. I do not know why you are choosing to go here, I run a Polk Audio 15" powered sub that I got on a deal from Amazon for about $150 and it evidently has a 150w plate amp in it?

Anyway, about 60 years ago I saw a sub output project in an electronic hobby magazine. I built it and it worked ok. You come off your amplifier outputs (+) with a couple of diodes. This isolates everything, you then run the combination output through about a 100k pot, and use a capacitor to trim out the frequencies you want.

Once you have your gain set you can forget it.

I just checked Amazon and I didn't see any deals, BUT I see them in thrift shops all the time. A powered sub is the way to go in my mind, but to each their own.

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.

You should write directly to Stephanie to get your answer. She's the quickest and most reliable source of information you will ever get here on this subject.

I do hope you can get your project, all worked out to your satisfaction. This is an interesting post, I have in the past run into this problem too.

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,

Will a converter work to isolate like this one? Stereo To Mono Audio Converter With Isolation Output Stereo/mono Adapter Hi-fi Audio Mixer - Home Theatre System - AliExpress

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.

This is my solution by using a RCA 2 into 1 Spliter And 2 x 1 RCA Male To 2 RCA Female AV Audio RCA. Sorry no image it was too big to post and not very good.

1 Rca Male To 2 Rca Female Gold-plated Copper Av Audio Rca One In Two One Male And Two Females Adapters - Audio & Video Cables - AliExpress

Hi-fi Sub-woofer Cable Rca To Dual Rca Splitter Y Cable For Sound Mixer Amp Sound Box 1:2 Rca Audio Cable 1m 2m 3m 5m 8m 10m 15m - Audio & Video Cables - AliExpress

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...

Well, I have the very same question. One possible solution is this. But, it also looks like a very simple DIY project... I would suspect there may be a more elegant and simple add to the project.

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