ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Deluxe Reverb clone hums

:

6/4/2000 7:28 PM

Deluxe Reverb clone hums

Before I dig in...The hum doesn't change with the volume control, it stays if I pull tube 1, goes away if I pull either tube 2(2nd & 3rd stages after volume control) or driver tube. There is no reverb or vibrato circuits in this clone.

Is it safe to assume:
1. The bias circuit is OK since the hum disappears when pulling tube 2?
2. Everything before the volume control is OK?
3. The transformers are OK?

Mike

6/5/2000 12:02 AM
Mike	I discovered the hum changes when adjusting the bias pot. This amp is using a borrowed bias supply from the 5AR4 pin 6. The hum decreased when adjusting bias from -35V to around -42V. Not sure what to do now.

6/5/2000 12:30 PM

Mike,

I think you can safely assume all three of the things you mentioned. The output tube bias affects AC output stage gain, so increasing the negative grid bias will reduce the volume of preamp hum. I believe you may have a grounding problem, and floating around here very recently was a long and excellent thread on this very subject. I would look long and hard at all your ground points; they deserve as much attention as your signal connections do.

Ray Ivers

6/5/2000 1:48 PM
Mike	Thats encouraging, I'll continue this thread in the Modify section under "Deluxe...Master Volume Mod"

Page 1 of 1