Silvertone 1474

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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.
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Ampeg VT-22-small.gif
Ampeg VT-22-small.gif (114.9 KiB) Viewed 1496 times
Silvertone 1474 reverb-small.jpg
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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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Re: Silvertone 1474

Postby DeathRex » Fri Oct 26, 2018 6:54 pm

Don't believe the hype. It's the reverb's fault. I finished this back last year and the owner said it sounded great, just forgot to update the post. Here's the rebuilt schematic. There's a few resistors that I changed to get more out of the reverb channel. And you have to be careful where you place the reverb, to keep feedback down. It probably would be nice to have another tube for gain.
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Dudes Silvertone 1474 reverb.jpg
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