Buzzing Superphon DM200(s)

[kirk57]

Hi-

I have 2 Superphon DM200s amps and a Kinergetics SW200 subwoofer amp that all make low level buzzing/humming noises both inside the case and through the speakers. I have disconnected all the gear they were hooked up to (just connected to speakers) and the problem persists. I have tried different outlets/circuits in my house, and tried changed plug polarity (none of these units have a ground plug), all to no avail. I also tried running a wire from the outlet ground to the chassis, no difference there either.

I could accept that they may make some noise, but a 35 wpc JVC integrated amp that I rescued on trash day is dead silent.

I've read through the postings on 60Hz hum in this forum here and one thing I saw was that the larger the amp, the larger the transformer and therefore the larger possibilty of such problems. All three of these amps are 100 wpc, but so is my Marantz 2330 reciever and it doesn't make a sound....

I have an old Altec tube amp that has a bad filter cap, that is much noisier than what I am hearing through the Superphon and Kinergetics so I don't think that is the problem.

Can anybody suggest some strategy to figure out this problem?
I really like these amps, but the buzzing is driving me crazy.
This keeps up and the JVC is going in my main system...

Thanks

Kirk

 

[kirk57]

Just a follow-up....Whilst searching around for some DIY interconnect info I came upon a post that suggested using foam pipe insulation on interconnects where they cross other cables. I tried this and and the hum went away completely.

So the problem was not the amp after all.....

 

[kirk57]

Oh and I should mention that the buzzing coming from within the amp was eliminated by the use of an old TV transformer placed on top of the case (a poor man's VPI brick)