[Tomo]

Hi,

[This is for UNBALANCED amps]

I have been fiddling my amps. (because I am a bit fed up with work. ...)

Anyways, I have been getting noise problems with newly wired passive preamp. The stepper switch is HUGE so I had to give it it's own chasis.

Anyways, this thing work for some amps, but for some it's "Hum" up. I tried all kind of crap; attaching passives, ferrites, wires, interconnects. But they didn't do a thing. Till yesterday, I would just swap to Pots or use volume control at the source. I just didn't have much time.

Yesterday, I was staring at the wiring in the preamp and I realized the grounds in left and right channels are not tied together. I speculated this can give a looong loop between the source and the amp. And, I promptly tied left ground and right ground together inside the pass pre chasis.

This killed my hum. ... Appearently, ground loop formed between the amp and the source through the left to the right interconnects. So you all take care to tie up your left and right ground at your pots. (If your amp is UNBALANCED that is.)

Cheers to the problem defeated,

Tomo

 

[rickcr42]

what's up Tomo.

I usually get away from the hum problem by grounding everything right at the input jacks and floating the output jacks and yeah that includes connecting the right and left grounds right there at the input where it counts most.

Glad you found the problem man because if anything can drive a human crazy it is trying to track down hum.....

 

[Tomo]

Hey Rick.

Yeah. I was missing the problem because it was the problem with grounding both channels to one spot. I was feeling OK connecting left ground to left ground, right ground to right ground. But I think you have to ground them ALL to one spot like you said, Left and Right.

Very cool ground looping example, don't you think?

Tomo