Best way to add a mono subwoofer output with only RCA stereo out available?

[boxerfan88]

How about something like this?

Crossovers | dbx Professional Audio | English (US)

Improve sound quality and speaker efficiency with world-renowned dbx crossovers. These crossover units deliver great performance, all the features you’d expect from a professional product, and the knowledge that you’re buying a trusted name who has been producing the world’s finest audio gear for

dbxpro.com

 

[Old_School_Brad]

This one works.

MONACOR SMC-1 Stereo to Dual Mono Adapter Converter RCA - Audiophonics

This small converter takes a stereo audio signal as input and outputs a dual mono signal. Interconnections are made on RCA connectors. The input impedance of the converter is 4.7Ω.

www.audiophonics.fr

 

[Tremolo]

I wonder why a y cable works for me. Are there risks that I damage the preamp or the sub?

 

[Sylvanus]

I wonder why a y cable works for me. Are there risks that I damage the preamp or the sub?

Probably not. Most sources have series output resistance, by design, for the purpose of decoupling.
So, if you simply "short" the left and right outputs together it might work just fine and not damage anything.

 

[Cote Dazur]

I wonder why a y cable works for me. Are there risks that I damage the preamp or the sub?

If it works, you are fine.
It all depend on the way the grounding is in your components, In any case it will not damage anything, but when it does not work, you might end up with everything working in mono or just sounding weird.

 

[janbth]

What I would really like is a component that takes line level stereo RCA inputs, provides RCA stereo outputs and one mono sub out. It would be great if it provided a way to set a high pass level for the RCA outs and a low pass level for the sub out.

What about a miniDSP 2x4 HD?

miniDSP 2x4 HD

MiniDSP 2x4 HD, a USB DAC+DSP in a low cost package powered by a powerful Sharc 400MHz floating point DSP. The upgraded on-board 400 MHz Analog Devices SHARC processor also ena-bles substantial processing upgrades previously available only on more ex-pensive platforms, such as 96 kHz internal...

www.minidsp.com

 

[Brian Hall]

What about a miniDSP 2x4 HD?

miniDSP 2x4 HD

MiniDSP 2x4 HD, a USB DAC+DSP in a low cost package powered by a powerful Sharc 400MHz floating point DSP. The upgraded on-board 400 MHz Analog Devices SHARC processor also ena-bles substantial processing upgrades previously available only on more ex-pensive platforms, such as 96 kHz internal...

www.minidsp.com

I'm looking at several options including building a simple box with the help of a friend who is good at that sort of thing.

Just stereo in with stereo out and one mono out for a sub.

 

[jayapple]

DSP can solve this problem, and for bass should use a special bass amplifier