SPEAKER HUM


I have been playing with a new system. I was driving my speakers with a MingDa MC 34 AB tube amp (75 wt/ch ultralinear 40wt/ch triode) which is powered with 8 EL 34 tubes. It can be used as an integrated amp, and when I used it as such, it was DEAD quiet.
I decided to make a good thing better, and just got the matching MingDa MC 2A3X preamp to go with it. The speaker hum when both are powered up is awful...not that very low level stuff you sometimes get with an amp/preamp set up...but loud enough to hear during quiet passages of musical pieces.
I have been tormented in the past with trying to eliminate speaker hum...any help out there for this system??
Thanks so much
rsasso

Showing 2 responses by millicurie999

Have you ruled out bad tube on the preamp (or simply a defective unit)? Also, are the amp and preamp both plugged in the same power conditioner or separate outlets?
As Swampwalker mentioned, amp and preamp in two different outlets can cause serious hum. Since you tried another preamp and it still gives you hum (albeit less), maybe it is indeed the ground loop introduced by different components in different power lines.

Can you borrow a power conditioner/surge protector and plug everything into one shared line?