At the risk of sounding like a newb, can you tell me how to trace the signal? That will give you about V across the 10K plate resistor. Taming the reverb on a super reverb. Have you tried running a guitar directly into the reverb recovery side? Very simple – replace the 12AT7 reverb tube with a 12AU7.
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OK, there’s a wiring mistake here somewhere! The problem then was a gated effect but lately I get nothing at all.
I pulled them and put the 12AX7’s back in, everything back to normal, no idea why they would operate hotter, but it made me uncomfortable with it. I ain’t fussy, they sound fine to me and I have at least 40 organ pull 12au7s.
I don’t think it’s your primary problem, but you should fix it before going further with the troubleshooting. Given that you’re getting loud?
R8 and R9 are definitely wired this way in the original circuit! Try replacing it with an audio taper type, eg http: Originally Posted by dchang0.
The Amp Garage
I’ll keep trying to optimize each stage. The drive side 12AU needs to pump revebr current so point A is out. I figure they must’ve been trying to use the impedance of the tank itself with the 27K resistor as a voltage divider of sorts. It’s the triode where the reverb gets blended back in and the combined signal goes on to phase inverter ie. Very simple – replace the 12AT7 reverb tube with a 12AU7. I dug rveerb an old Blues Jr. They can and do open up electrically.
What I haven’t mentioned is that this design is based on a boutique amp which in turn was almost entirely based on the Gibson Scout.
Got any schematics for a 12dw7 reverb? | Telecaster Guitar Forum
Jan 29, 3. The only Scout I could find a schematic for used a transformer rwverb reverb and was nothing alike. Thanks very much, guys! This will absolutely confirm the recovery side is working and eliminate it from worry.
Maybe the tank itself is bad. A safer test might be to grab a pair of cheap computer speakers or headphones and hook them to 12ds7 reverb driver RCA out. Anything else i should look out for when doing so? Awesome–glad you fixed it! Jan 29, 2.
I’m used to thinking about voltage gain in triode stages, and not current gain, but this is running very close to, or even over max dissipation, and with recerb extremely steep load line. Voltages are a little higher than I guessed they’d be. That means that either the 8FB tank was damaged in shipping or its input impedance is too high and blocks the signal.
Since you’re a newb, I would advise connecting scope probes to the points revern trying to test with the amp OFF.
Got any schematics for a 12dw7 reverb?
This is definitely a lousy town for tube amp techs! But point A will probably increase to Eeverb. The reverb control has a linear taper. Jan 29, 4.
Is there away to make the reverb pot more sensitive so that 5 is the maximum amount of reverb and therefore becomes 10 thus giving me extra control between revwrb and 5 which would become 1 and 10 if you catch my drift.