Hoping you gurus can help. I did a "retro" build of a princeton reverb. Everything works perfectly unless I try turning the reverb up. When I do, the volume decreases quite a bit (more than half). Reverb does work, just lose a lot of volume.
I have checked and rechecked wiring and components. Replace tubes a couple of times. Does it whether tank is plugged in or not. I've attached pics. Open to any suggestions.
Reduced volume with reverb on princeton
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Reduced volume with reverb on princeton
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Re: Reduced volume with reverb on princeton
This one is a real puzzler. Can anyone tell me what kind of signal level I should see coming back from the reverb tank compared to the tank input? Also, shouldn't the signal out of the reverb recovery tube be in phase with the signal out of the 2nd preamp tube (input of 3.3 meg resistor)? Mine appears to be out of phase.
If I disconnect the tank and jumper across the reverb jacks, there is no loss of signal. Really confused on this one.
If I disconnect the tank and jumper across the reverb jacks, there is no loss of signal. Really confused on this one.
Re: Reduced volume with reverb on princeton
You may have oscillation due to lead dress at the reverb tube driver socket. There was a thread recently on this subject. The plate wire (pins 1 and 6) must loop AROUND the socket:
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I build and repair tube amps. https://www.monkeymatic.com
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Stevem
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Re: Reduced volume with reverb on princeton
If you unpower the reverb drive transformer ( lift the red wire does the volume drop still take place?
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Reduced volume with reverb on princeton
Just adding to what xtian said. This may not fix your issue but there is some reason that Fender looped that pin 1 to pin 6 jumper on all their amps, including the PR.
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...Steve
Re: Reduced volume with reverb on princeton
I'll try the looping trick. Disconnecting the reverb transformer still has the same issue.
Re: Reduced volume with reverb on princeton
EDIT: mistaken post.
Last edited by B Ingram on Sat Oct 18, 2025 3:30 pm, edited 1 time in total.
Re: Reduced volume with reverb on princeton
I see orange-orange-green, which should be 3M3, no?
What I'm not seeing is the 220K to ground from that same junction.
IDK
What I'm not seeing is the 220K to ground from that same junction.
IDK
Jack Briggs
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sluckey
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Re: Reduced volume with reverb on princeton
I agree.
The PR does not have that 220K to ground like the AB763 amps.What I'm not seeing is the 220K to ground from that same junction.
...Steve