Is a sub on a different circuit often a problem?

I'm in the process of rearranging my HT system in anticipation of eventually getting a flat panel TV that I plan on mounting on the wall. So I'm wiring new A/V connections to the new site of the A/V equipment.

I plan on moving the sub to a different corner than where it is now. As of currently, I don't have an outlet to the dedicated 20A home theater circuit in that corner for the sub to use. I could always wire one, but I first wanted to get a sense from people here if they actually have ground loop / hum problems with a sub on a different circuit or not before I take the time to do it.


I think that having it on a different circuit increases the chances of having different ground potentials creating a current loop and hum. It all depends on your wiring. Even a different outlet on the same circuit can cause differing ground potentials.
Bob_reynolds is exactly right.
One way to deal with this is to create a custom PC with high quality 10 or 12 gauge wire and quality terminations. I did one (30') from BPT with good results, and at reasonable cost. Then you plug it into your dedicated circuit.
Twb2, if I understand you right, you're suggesting that I make myself a long extension cord? I can hard-wire a new outlet close to where the sub will sit with about 2 hours of work chiseling a space in the brick to place the box and then fishing the wire down to the basement. This would definitely be my preferred method of handling it, because it's safer and more aesthetically pleasing (just in case one day I have to consider the WAF).

Bob Reynolds, have you experienced the hum when they weren't on different circuits? I'm just trying to get a sense of the probability that I'll have to deal with this.

Michael, yes essentially you are correct, but with an IEC fitting, so you would have fewer connectors vs. an outlet plus PC. But an outlet, done right, is probably the better long term option, if you are sure the need will remain.
Sufentanil, sorry no I don't. My main system plugs into a single outlet via a SurgeX SA1810; my office system is into a single outlet as well. I also use a Jensen isolation transformer on the cable TV feed. If it's not a big deal to retrofit another outlet near the sub, then why not wait and see if you actually have a problem. You could use a Jensen subwoofer isolation transformer to break the ground loop if it occurs.

Jensen Subwoofer Isolation Transformer They will build one with XLRs if you need.