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previous: Richie What are the screen voltages, as co... -- 2/28/1999 11:14 AM View Thread

Re: Hum problems (open to suggestions)

2/28/1999 12:56 PM
MJ Harnish
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Re: Hum problems (open to suggestions)
No I haven't since I was fairly sure it was related to the first gain stage; however, I can see how the zener could affect this indirectly so maybe I need to experiment here as well. I'm pretty sure the amp was fine after the zener was added.  
 
The hum problem really got bad after my latest tweaking in which I fixed a few minor bugs. I even went so far as physically moving the first tube socket using one of the remaining empty holes the chassis has. No luck here. I also rewire the filaments with a very long lead so that I could pull it WAY out of the chassis and move it to see if it affected the hum. NO effect at all. It seems like the B+ has got to be the culprit so that also makes me suspect the zener, but I would think that if it was causing some sort of problem that it would show up in all the stages. I'll measure all the voltages, etc. this afternoon and report back about the findings.  
 
Thanks for all the suggestions. As I've said before, this stuff seems like voodoo sometimes...  
 
MJ