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REL subwoofer hum

I own a REL stadium III, and have owned it for some time now. Just recently I noticed that it will produce an audible (although low level) hum when I turn my system’s amplifier off. I have the Stadium hooked up in the recommended manner: I have it hooked up with the neutrik cable to the Speaker B terminals of my amplifier. Speaker A terminals are occupied by my Sonus Faber concertos. When both sets of speaker terminals are on, the sub is quiet. When I turn off the B speaker terminals, or turn off the amp altogether, a low level Hum is output by the REL. I have not noticed this hum before and believe it to be a new occurrence. However, I guess it could be a ground hum. My main amplifier, and the REL are plugged into two different outlets, both outlets have quality AC filters/surge protectors, and I use the stock power cords for the amp and REL. Should I alter my hookup method? Would better power cables help? I really don’t want to have the REL serviced as, I’m sure you know, it weighs 110 pounds, and I don’t want to have to move it. If it is a so-called "ground hum", how do I alleviate it?

phoenix469
artmaltman
769 posts
 
Alas, I still do have a slight hum under the one circumstance that you describe: when the amp is powered off and the sub is powered on. Not a huge problem of course but disappointing.
Art
steam3642
124 posts
 
Hi there i have the same problem with my Musical Fidelity Kw -500 using a Rel R-305 subwoofer , turn the Musical Fidelity of and the hum starts turn it back on and i wait 30 seconds for the preamp section to kick in and the hum goes and the Rel works as per normal , i use the speakon connector , strange thing is i have also got a Redgum Audio RGI - 120 Integrated amplifier as a spare and when i connect it up the same as the Musical fidelity Kw -500 i have no problems and the Rel has no hum , so my hum problem is isolated to the Musical Fidelity integrated and i have also tried grounding it to the chasiss to no avail . Anyone had a problem with hum on M/F amps ?
tmsorosk
1,013 posts
 
60hz hum or what some call a ground loop problem is common with subs . Audioquest has a sub interconnect that has a ground lug built in , it solved the problem for me . I've not heard of chassis grounds ever harming a component or causing a warranty problem .
Floyd Toole said everything should be grounded to the preamp , to get the lowest noise floor possible .
steam3642
124 posts
 
I tried again with another wire combination on the
M/F kw 500 , as per the Rel manual : red wire to right channel positive , yellow wire to left channel positive and black wire to negative left channel . I found that if i connect all 3 wires to either the left or right channel the hum stops when the m/f is powered down and runs as per normal when powered up Rel appears to operate fine , would this be due to it having a bridged/dual differential internal design , apparently both left and right channels are
open/hot aand feature a bridged output.
steam3642
124 posts
 
I have removed the hum when the Kw -500 is turned of by connecting the 3 wires of the speakon connector to one channel of the musical fidelity , instead of running the red wire to the left channel i have connected red and yellow to the right channel along with the black ground wire. Not sure if this is an acceptable solution but does not appear to be having a negative affect on the amplifier
So all 3 wires are now connected to the right channel and no hum when powered down and m/f and rel works as normal when powered up.
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