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Re: Master volume for Deluxe Reverb clone?

6/5/2000 1:54 PM
Re: Master volume for Deluxe Reverb clone?
I found this in the "Build" section. Sorry, I goofed up with the new format here.  
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?  
Read 15 times  
From: Mike (  
Date: 6/5/2000 12:02 AM  
Subject: Re: Deluxe Reverb clone hums  
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.  
Read 3 times  
From: Ray Ivers (  
Date: 6/5/2000 12:30 PM  
Subject: Re: Deluxe Reverb clone hums  
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  
From: Mike (  
Date: 6/5/2000 1:48 PM  
Subject: Re: Deluxe Reverb clone hums  
Thats encouraging, I'll continue this thread in the Modify section under "Deluxe...Master Volume Mod"  
6/6/2000 1:21 AM

Almost there. I bypassed the 3rd stage by attaching the input to my new master volume control to the coupling cap of the 2nd stage. No more hum, but I guess you guys figured as much.
6/6/2000 8:28 AM
Steve Ahola

    Can you disconnect your new MV and wire the resistor(s) back in just to see if the hum is still there? If it disappears, then when you wire the MV back up, try connecting the CCW terminal to different ground points in your circuit to see if that changes anything (even try the chassis ground for the heck of it!)  
    You might also try checking the lead dress- like moving the wires around with a wooden or plastic chopstick.  
--Good luck!  
Steve Ahola
6/7/2000 1:40 PM

Bruce, with the master volume; When I add the normal channel(with "cool mod") back to the amp, will I also need to put the 220k resitors back in before the master?
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