Modifying onboard spring reverb

[David]

I have an Epiphone SC-208 amp.  It's a stereo 25? watt solid state amp with onboard chorus, distortion and spring reverb.  The chorus sounds great and the distortion does not make me ill.  For church use, it was a pretty good investment -- especially when the chorus and distortion are footswitchable.  Unfortunately, the reverb is not -- which prompts this post.

I have not modified or replaced spring reverbs because I have never had the desire to.  I really don't now -- especially since the reverb send and return circuits are probably built right into the amp.  There are RCA cables with white and red connectors going to the reverb tank.  Now, my question is this:  Could I make a sort of "T-connector" that would tie in, say at the reverb output, that would have a male RCA plug to go into the reverb tank and a female RCA plug for the cable from the amp -- which would also have a stomp switch to shunt the signal to ground? I mean, I have the signal line and ground right there....

[Paul Marossy]

I'm not sure how it's normally done on solid state amps, but I imagine it could be switched off just like it would be on an old Fender amp. I believe that the old Fender amps just ground the signal going to the reverb circuit.

[David]

By no means do I intend to challenge your knowledge.  However, if you mute the reverb input, wouldn't you get noise from the return transducer?

[Paul Marossy]

By no means do I intend to challenge your knowledge.  However, if you mute the reverb input, wouldn't you get noise from the return transducer?

My mistake, I think you are correct. That's the way it's shown on my Fender Twin Reverb schematic - it grounds out the reverb tank output. It's been a while since I looked at that schematic!

[Paul Marossy]

Any progress on this yet? Just curious about it...

[David]

No.  Possibly this week.

[David]

Any progress on this yet? Just curious about it...

Yes.  There is progress, as a matter of fact...

IT WORKS!

[Paul Marossy]

Any progress on this yet? Just curious about it...

Yes.  There is progress, as a matter of fact...

IT WORKS!

Awesome! 

I thought it was basically that simple, but it's a mod that I haven't actually tried doing before. Good to know! 

[Thomeeque]

By no means do I intend to challenge your knowledge.  However, if you mute the reverb input, wouldn't you get noise from the return transducer?

My mistake, I think you are correct. That's the way it's shown on my Fender Twin Reverb schematic - it grounds out the reverb tank output. It's been a while since I looked at that schematic!

IMO the best way would be to mute both input and output, so there's no noise from the reverb unit and there are no "trails" when you turn it back ON.. T.

[Paul Marossy]

IMO the best way would be to mute both input and output, so there's no noise from the reverb unit and there are no "trails" when you turn it back ON.. T.

Fender doesn't seem to care... 

[David]

You know, the odd thing is that it actually worked on either reverb tank connection.  Using the white one seemed to be slightly less noisy (although this was not a real-world test).  Tomas identifies the complete solution, but muting the reverb return is probably the practical solution.

[Paul Marossy]

You know, the odd thing is that it actually worked on either reverb tank connection.  Using the white one seemed to be slightly less noisy (although this was not a real-world test).  Tomas identifies the complete solution, but muting the reverb return is probably the practical solution.

If it worked for Fender... 

[Nasse]

If fender does thousands of amps, they must cut costs and complexity. For those, who want rails but no noise the ideal system might be such that does mute that other (and noise) and noise with suitable delay, after "trails" have decayed, but opens at once when needed.