I don't have a solution, but I do have a similar problem with the new Belles 150A Reference. The problem did not manifest itself until I attempted a speaker cable upgrade from the shielded LAT SS-800 to the unshielded Xindak FS-2 copper/silver foil. Result was a very loud hum, even with everything but the amp unplugged and the inputs from my 21A pre-amp disconnected. Problem is continuous with the unshielded cable, and is loud enough to make listening to music impossible (all with pre-amp completely removed from the sytem). Problem goes away when my old speaker cables are re-installed (yes, I checked multiple times to make sure I installed the new cables correctly). The hum changes pitch when I move the speaker cables around, but never goes away - I'm no EE genius, but to me, it would seem more logical that this is an EMI problem coming from the amp itself than a ground loop problem, since it goes away with switching only the speaker cables. I also tried lifting the ground from the amp PC with nothing else connected to the amp or plugged in to any outlets on that circuit - hum persisted. I also tried plugging the amp directly into the wall (my normal method) or into my Panamax line conditioner, with no change. I do, however, have dimmer switches installed throughout the house, and I'm not in the mood to replace every switch to see if that might help! Other than this recent challenge, I have been thrilled with the 150A Ref/21A combo. Any other ideas?
Belles amp hum ... rf problem?
Hi all. I have a noticeable hum problem which I have isolated as coming from my power amp, Belles 150a hotrod. The amp hums when I have it plugged into the wall with nothing else attached. The hum is not always present. I'll go a couple days without it and then it will re-appear ... comes and goes. I called David Belles and he told me the issue was likely a quality of electricity problem which was exciting the torroid transformer. (I live in a large apartment building in Manhattan.) He recommends a RF filter. Can anyone recommend a RF filter brand? Would something like a Blue Circle Noise Hound or PS audio ultimate outlet/power conditioner serve this function? If it is a electrical problem I don't think it's coming from within my apartment. I've unplugged everything that I can and the hum persists. Help it's driving me crazy. I may be imagining this but when it does hum the system doesn't sound as good. High frequencies are really grating. Thanks in advance for any suggestions.