Silvertone 1474

a fine line between stupid and clever

Silvertone 1474

Postby DeathRex » Wed Nov 22, 2017 5:25 pm

So dude brings a Sivertone 1474 to fix. It's all stock. It does kinda work except for 2 burnt resistors and the reverb. It has a piezo reverb that they don't make any more. I've been researching and researching, and everyone just says to match your old reverb with a new one. Since I can't, I decided to rewire the circuit for either a 6CG7 or 6N1P driving a 8FB2C1B since it had the highest impedance (1925Ohms in). The Ampeg Gemini 1 used a 6CG7 to drive a reverb tank, but they didn't say what the impedance was.
I don't want to add another tube, just remove the 2nd 12AX7 and put in a 6CG7 or 6N1P, both can get down to 6.5KOhms internal resistance, with the 6N1P giving me a lot more gain.

Will the MOD 8FB2C1B that I already have :( mate up with a 6CG7?

Top picture is the Ampeg, bottom is the Silvertone.
Attachments
Ampeg VT-22-small.gif
Ampeg VT-22-small.gif (114.9 KiB) Viewed 70 times
Silvertone 1474 reverb-small.jpg
Silvertone 1474 reverb-small.jpg (167.8 KiB) Viewed 70 times
At first I wanted to be a ET. Now I are one.
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Re: Silvertone 1474

Postby DeathRex » Thu Dec 07, 2017 2:31 pm

Well I got the resistors and caps replaced. It all does work, except I'm getting a small bandwidth through the reverb. From 1khz to 2.3khz I'm getting about 4 times more signal out than at 600hz or 6000hz. In that band I'm getting more signal than through the non reverb channel. Why is that?
At first I wanted to be a ET. Now I are one.
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