Can someone tell me what wrong


Hi there
i need some held with speaker hissing noise
i recently noticed some noise come from my right speaker 
the speaker is venture audio grand mk3 and driven by vta m125 tube mono block, it’s kind of loud, i can hear it from 4 feet away the speaker with the preamp turn off, it doesn’t effect by the preamp volume 
so here is what i did
Remove the preamp - still the same noise
swap the mono block - still the same noise
swap the speaker cable between left and right - still the same noise
hook up a vintage dynaco st70 - no more noise
hook up the right channel mono block to the left speaker - no noise 
so what could be wrong here?
I didn’t have that noise before 
This thing really drive me nut
Thank in advance 
 

128x128ownut
Just for some folks info not sure if it applies in this case.  I had a ground issue once and I solved it by connecting the ground wire of my Rel Speakon connection to the Preamp.  The left and right channels were being driven by the speaker outs on the power amps.  This happened with both two channel amps and mono blocks.

oldhvymec1,304 posts10-30-2020 9:36am

Ya know OP Erik has a "clean side", "dirty side" solution. He might chime in. I’m sure the transformer is an option, but "dirty, clean" power supply is a LOT less expensive..

In my case being VERY careful how I routed cables has always fixed my issues.. I’ve done it a LOT of time through the years for friends too. They are just astonished that cable routing could cure a noise problem AND over all, sound better...

Regards