Silvertone 1482 1 tube reverb

[Edhelmstetter]

Hello All
First time posting here
Just wondering if anybody who has put a 1tube Reverb into a 1482 could you please tell me where you connected the Transformer and recover plate to the B+?
I cannot seem to get rid of this hum and I'd like to rule out
the B+ nodes as the cause if possible.
Thanks in advance
Ed H

[sluckey]

Here's one take. I did not do this. You can find more info about 1482s and one tube reverb on hoffman's forum.

[Stevem]

What is the hum you have?

120 hz is from the B+, 60 hz is from the power transformer or the heaters.

The output end of the reverb pan can not be anywhere near the power transformer, at least 10” we are talking here.

If you place a short across the output cable does the hum get reduced drastically?

How much ac ripple do you read on the plate of that reverb tube as compared to the plates on the first preamp tube.

In general a good rule of Thumb for low noise or oscillating problems is to not have more then two gain stages on any one power supply filter node.

[Edhelmstetter]

Thank you Stevem for the reply
The RCA jacks on the other side of the chassis from the power transformer
I pretty much swapped everything out of the reverb circuit and the filter caps which should have plenty of life in them but I can't think of anything else that would be the problem
The hum sounds like a B or B flat note on my guitar A string so I'm guessing 120....
I was hoping somebody who hooked up a1 tube Reverb to a 1482 successfully could tell me exactly where/which nodes they used
Edh

[Edhelmstetter]

Thank you Sluckey for the reply
I downloaded that schematic plus many others and I've been to the Hoffman site and I read a lot about the 1 tube curcuit
I just cant find a good node to connect to
I've tried all the nodes..I think...
I'm reluctant to swap out the filter caps but I'm pretty much down to that last resort
Edh

[Stevem]

I would increase that B power supply node to 30 uf and that new parallel C node to 30 uf also.

[Edhelmstetter]

Thank you Stevem
I also saw no considerable ac ripple at any of the plates
Barely a mV maybe...
I havent tried a metal tube cover for the 12dw7 yet, gonna try that next
I guess I should mention the location of that tube. I actually used the area where the cap can used to be I took that out and put a preamp tube Jack there. You think it's too close to the power transformer?
Edh

[Edhelmstetter]

Well I tried the tube cover and it seemed to make a huge difference.
I also rewired it a la Uncle Doug with just the one
1meg pot on the input and a fixed 1meg resister for the ouput It's way more reverb than i need
Thanks again for the helps
Edh

[Stevem]

Well glad it’s all good now, but that’s a detail you should have included in your first post.