Subwoofer hum when connected to Shindo Montille
 

I have a a REL Stampede sub (power strip -> mains) connected to the speaker terminals on my Montille (->Mr T ->Belkin PF60 -> mains). I cannot get rid of sub hum no matter what I try. The cable from the sub has three wires, connected yellow to one red speaker terminal, yellow to the other speaker red terminal, and black to the black terminal of one speaker only. The hum starts after connecting the second + wire to a speaker terminal where it appears a ground loop is introduced. The hum is present whether the amp is connected to the preamp (earthed) or not. Any ideas what I might do to get rid of the hum?

Are the Rel and amp driving your speakers on plugged into a different outlets / circuit?

Hi Tony, sounds like you have it correctly wired @ the amp.

Plug the REL a/c cord into the Mr. T. Or - use a cheater plug on the Rel and lift it's earth, if it's in a different location and can't be powered with the Mr. T.

-M

Thanks for suggestions. Yes, sub and amp on different outlets. Connected sub to Mr T and hum reduced considerably although still present and obtrusive when High Level control at 55 or higher. I'm not too keen to use a cheater plug, so might look at an isolating transformer.

Nothing wrong with cheater plugs, and in this case, I'm almost 100% positive it will be the solution for the REL's a/c cord.

-M

OK, thanks Matt, will give it a try.
Further experimentation in the meantime shows hum occurs in sub even when Montille amp (to which sub is connected) is powered off ... a bit puzzling. Connected the same sub to the speaker terminals of a Quicksilver monoblock, on same mains outlet, and there is no hum at all.
I have to admit that I have a lot of electrical 'stuff' in the man-cave, so probably due for a proper tidy-up of mains connections.

What else do you have plugged in to the preamp? Is the preamp in any way connected to a piece of equipment using the coax cable line (Cable box, etc???) The coax cable is grounded outside of your house (same place as your breaker box) and some times it can get some corrosion on it and will cause the ground loop. Try and disconnect one component at a time until the hum goes away. If this works I can talk you thru the rest....

The quicksilvers probably have three prong power cords. The Montille doesn't, hence the need to use a cheater on the REL, IMO.

-M

Josh, I disconnected my cable co-ax from the satellite box, but hum remained, so not that ... thanks for suggestion.
Well, I got rid of the hum. Unplugged Mr T from the Belkin PF60, and plugged it (him?) to a second socket on the same double outlet to which the Belkin is connected, and hum totally disappeared. However this means the precious green boxes now don't have overload/surge protection other than the switchboard RCD so I will need to do something about that!
Thanks for the help ... will also get a cheater and test that option out of interest.

Ah.. The Mr. T was plugged into a surge protector, which was, in turn, plugged into the wall? Gotcha..I missed that point in your original thread. Just plug Mr. T direct into wall outlet.

The Shindo gear will sound superior direct into Mr. T-> Wall. I've never had a Mr. T (Transformer) damaged and/or gear ever damaged from a storm. And I have customers all over the country in various climates. Worse that happens is the fuse pops.

-M