Summing L/R signals, then sending to a distant subwoofer

[rif]

I'm looking to use my preamps 2nd set of outputs to send a signal to a sub that's across the room. There's already a single coax wire in the walls to accomplish this. It's maybe 30ft of cable. The sub has its own amp, and can accept a single line level input.

I plan on using the textbook circuit for summing 2 inputs using an opamp (maybe TL072).

I'm not sure if the length of the output wire needs special considerations. If it does, there must be a simple device that handles this, but i don't know what that might be.

Thanks!

 

[rayma]

Just a couple of series 10k resistors should work ok for a sub mono feed.
The cable capacitance won't matter for the sub.

 

[rif]

Series resistors instead the opamp?

Something like this:

 

[rayma]

Yes, that should work without problems. If you have a choice, it's preferable to install them near the sub.

 

[rif]

Thank you for the quick help. Unfortunately when I had the room remodeled, I was using an AVR with a single coax run. Now I've removed the HT receiver system to a tradional 2 channel setup (no HT processors or amps).

 

[rayma]

That should be better. What will you do with the speaker wires?

 

[rif]

The HT speakers (5.x) are all in wall/in ceiling at high level input. The 0.1 sub is a typical standalone and uses has coax (line level) run through the ceiling and walls. I'm going to salvage that.

The ends of the 5 channels are left unconnected in a built-in cabinet. The 2 channel system doesn't use them at all.

 

[rif]

In case anyone wants some visuals:

Bamboo onkens with enabled drivers
N-channel vfet lottery amp
Wryed4sound dac
Apt holam preamp
Aliexpress display thing
APC g5 power unit
Marantz digital recorder
Daphile streamer
Pearl3 phono stage
VPI HW19 mkIV turntable, with lots of mods
Phoenix roadrunner tach
Ma3d speed control.

If anyone is interested in the headphones + ReadRoom anp, let ne know

 

[rayma]

You literally won the lottery.