VH-4 Channel 4 EXTREMELY noisy... preamp tube help?

[MikeDV]

@ paulyc
I was lucky mine was just an adjustment, sounds like yours had bunches more problems happening inside and out. I usually have similar stories, this particular one had a happy ending. Sorry it didn't work out for you.

@ sigma
my guy and I talked about changing that trimmer to a couple of resistors as well. He wondered why it was designed that way, and of course I had no idea. We decided that this simple move fixed the problem, so why push it further. I'm sure there was some reason in the design, maybe that was changed later - and even given a reason, there's a good chance I won't understand it... If it for some reason changes back to noisy in the future, that's the first place I'll look. Possibly movement? Mine was shipped to me from San Francisco.

 

[paulyc]

Was Jens the guy in LA ? I think that was the guy they wanted me to ship mine to, and then I heard some nasty stuff about people not getting their amps back, him renting customers amps to LA studios, and all kinds of stuff...hence the no longer working with Diezel deal.

 

[Peter Diezel]

Was Jens the guy in LA ? I think that was the guy they wanted me to ship mine to, and then I heard some nasty stuff about people not getting their amps back, him renting customers amps to LA studios, and all kinds of stuff...hence the no longer working with Diezel deal.

Pauly,

please send me am email to peterdiezel (at) diezelamplification (dot) com

 

[1meanplexi]

After exchanging a couple of emails directly with Peter, I took the amp to my tech here in Phoenix. Peter had mentioned a possible "hum trimmer" as a potential problem. The tech opened it up, looked at that thing (like a little volume pot on the circuit board), turned it with a tiny screwdriver and now it's the quietest high-gainer I've ever had.

Too bad those of you who got rid of them because of this problem weren't lucky enough to find the problem so quickly/easily/cheaply. Now with new preamp tubes, and no hum/buzz, it's positively a fire-breathing dragon ready to wipe out any comers. Bring it on, Joeffrey! (game of thrones reference, for you non-nerds out there).

This is really interesting. This question may come as one that should be obvious but did your tech have the amp on and while on reduced the hum trimmer? Did it have any effect on the tone, volume of the other three channels. I am really curious and thanks in advance for your answers.

On a side note, someone had mention removing that trimmer. I looked in my Diezel tech manual and there is a section that shows how to replace that piece. Specific to the VH4S.

 

[Peter Diezel]

Any news ?

Thanks,
Peter

 

[MikeDV]

@1meanplexi - yes, it was on. He removed the chassis, set it on his bench, and located that trim pot. He plugged it in, turned it on, plugged in a guitar on channel four, and turned that pot until silence resulted. I didn't hear any change in tone at all or real noticeable effect on the other channels. 3 was noisy at high gain settings (nowhere near as much as channel 4), and that simmered down a bit as well. If you're willing to take the chassis out, this is a user adjustment - as long as you're careful about grounding/touching other items in there - as warned by my tech.

 

[1meanplexi]

@1meanplexi - yes, it was on. He removed the chassis, set it on his bench, and located that trim pot. He plugged it in, turned it on, plugged in a guitar on channel four, and turned that pot until silence resulted. I didn't hear any change in tone at all or real noticeable effect on the other channels. 3 was noisy at high gain settings (nowhere near as much as channel 4), and that simmered down a bit as well. If you're willing to take the chassis out, this is a user adjustment - as long as you're careful about grounding/touching other items in there - as warned by my tech.

Thanks for the reply. I own a plastic screw driver !