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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 
 

ownut

Showing 2 responses by oldhvymec

oldhvymec
5,101 posts
 
If you reed the post he did swap monoblock

"swap the mono block - still the same noise"

Ok in order try these they cost nothing.. The way a mechanic would kinda do it..

1. Noisy valve, ay? You have a tube making noise? (Swap valves left to right for a check)

2. The mono blocks aren't on the same plug? Make sure they are plugged into the same rail on the meter. For now the same wall plug, or maintainer will work.

3. Make sure the IC (source to preamp AND preamp to amp) are tight, clean, and plugged all the way in. 

4. Get a cheater plug for the ground. Eliminate the ground with the cheater, ONE amp at a time. Repair the ground loop as needed. add a ground wire between the two amps, chassis to chassis.

You gave a good report, OP a lot better than most..

I'll give it a guess, a noisy valve, or a ground loop issue between the two monoblocks..

Happy hunting.

Regards




oldhvymec
5,101 posts
 

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
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