Should Subwoofer Be Plugged Into Same Circuit?

It should be a law of audiophiles that everything should be plugged into one outlet. That is the best way to eliminate ground loops. And sometimes the only way.

If the system is wired so all the grounds home to a single point, multiple outlets are fine. Recording studios have dozens of outlets with amps, mics, effects, recorders, etc. plugged into them. Ideally with balanced lines and screen lifted at destination. Every studio I wired or fixed was dead quiet with the monitors on S T U N.

Many powered subs do not use a grounded connection, so an additional extension outlet is fine. If the sub is grounded and unbalanced, I'd be wary of a branched line. I've seen grounded unbalanced monoblocks plugged into the same socket hum a little while individually each was dead quiet.

The power loss between ≈50 foot run of 10 and 14ga @ 14A [≈1700 watts] draw is an inconsequential 0.17db. See https://forum.audiogon.com/discussions/headroom-loss-for-1600w-on-14ga-120v

A Class B resistive breaker has a 3-5x multiple of rated capacity [For a 15A breaker that is 45-75A or ≈5000-9000 watts] for a couple of seconds. Your voice coils are vapor by then. See https://www.c3controls.com/blog/understanding-trip-curves/

IMO, there is no need for GFCI in a HiFi as there should be next to no chance of water at the equipment.

So if I read between the lines ieales you are saying a 20 amp circuit is unnecessary.

i was curious about the gfci because unfortunately my theater back up to my washing machine in the other side of the wall and has water lines running above it. That’s the trouble with a theater in the basement. Of course a gfci isn’t going to do any good of water is leaking all over the equipment. Lol 

Subs are typically Class D.....don't use much electricity at all  Craigert...I have a gizmo called FloodStop on my water heater, washing machine, water conditioner, etc.  If it senses water on the floor, it immediately shuts it off.  Easy to install....very effective. Get it at Home Depot.

@craigert, being familiar with Ieales’ posts I can vouch for the accuracy of analyses he provides. Also, given the equipment in your system that you’ve listed in another thread, namely:

Sony OLED TV, Marantz preamp processor, Atoll amp, cable box, nighthawk router, Xbox, Rega P3 TT, and powered 12” subwoofer with 2 stereo speakers.

... it seems safe to assume that a 15 amp circuit and 14 gauge wiring of reasonable length (e.g. 50 or 75 feet or so) would be suitable for powering your equipment.

Of course installing a 20 amp circuit can’t hurt, and conceivably could provide added flexibility in the future. I would be more concerned about the drop of a volt or two or three that would occur due to the resistance of that wiring (depending on the current drawn by the components as well as the length of the wires) if a tube amp having unregulated filament (as well as high voltage) supplies were involved. And there are some very high powered solid state amplifiers which can require a separate 20 amp circuit even for each of two monoblocks, but those are big, heavy monsters which typically are at the extreme upper end of the price spectrum. Different animals altogether.

Regarding the possibility of adverse sonic effects from GFCI or AFCI/GFCI outlets, I have no particular knowledge. FWIW, though, my instinct would be to doubt that there would be any adverse effects. For one thing, if significant voltage was being dropped in their contacts they would be heating up significantly.

Best regards,
-- Al

@almarg 

Thanks for the link to Bill Whitlock's paper!
I was aware of the nasty effect from dimmers. Seems the paper is pre-LED lightning emerged. Are you aware of how "noisy" LED power supplies are and/or how to mitigate said noise being injected in the circuit? I'll be making changes to my room and this is a topic I had in mind.

FWIW, lights are on separate circuits in my house.

Regards