Spectral DMA 360 hum

Sounds like a groud loop problem. Trying removing your cable TV connection from your receiver or pre. once the cable has been removed if the hum stops then that would suggest a ground loop problem. A jensen transformer ($50 bucks on Ebay did it for me)Model # VRF *** good luck

What preamp and cables are you using?

Spectrals are VERY sensitive and Spectral pre's and MIT cables are almost mandatory.

Try floating the ground on the amps using a cheater plug. I had to do this on my stereo Spectral amp to eliminate hum.

Me too. I had to use a cheater plug on my Spectral DMA-150. Now, anybody know where you can get a cheater plug that doesn't look like it came in an xmas cracker?

Hi,
thank you for your answers!! Appreciated. Answers: I use my Elgar Plus dac as a pre-amplifier (have to start saving for a 15 of 30 SL... Problem must be something with the grounding. I did an experiment with an extension power cable (30 meters), plugged it into another grounded AC outlet and the hum decreased by 90 percent!! Which is totally acceptable. Still doesn't really indicate the problem precisely (is it the specific (audio) AC outlet which has the problem?. But I am really glad that the Spectrals themselves aren't the problem: don't want to miss them a minute, they are great! Have never seen a cheater plug (European) but will find out. Does this mean that Spectral doesn't really need an earthed AC?
Again: thanx for your input! Wim

Wim, I hope you are using Mit wires from your Elger to the Spectrals. If you are not you run the risk of the Spectral going into oscillation. This will fry the output
devices. A high pitched hum is an indication of oscillation. Spectral was designed to use Mit cables and nothing else...period!

Hi Drjoe,
yep, Spectral and MIT all the way (speaker cables 770 Ultralinear 2 and interconnect (unbalanced) Oracle 3.1). Not really a high pitched hum as a low pitch rumble... With nothing attached than the speaker cable is hums, with interconnect attached the hum increases.... But as stated, connected to a different (out of the listening room) grounded AC outlet, the problem is almost gone. Got to have an electrician to have a look at this. Maybe shift the amps away from the converter? Read that this might also help... Keep you informed of progress. Again, thanx!!