Turn up the reverb... and the suck

[slippingglimpser]

Well, I finally made a reverb/tremelo footswitch for my 190L.  It works great, but here's a problem:  When I normally turn up the reverb, the tone gets harsh 'cause that's how the sunn reverb sounds.  I like it.  However, now when I have the reverb turned up but turned off with the footswitch, the sound is clean (no reverb) but still that same harsh tone.  Clean, it sounds real bad and my reverb is basically now a suck dial when I want clean guitar.  Does anyone know why this is or what can be done about it?  Thanks very much.

[Anonymous]

Did you use shielded cable for the reverb portion of the footswitch?

[Anonymous]

Well here's the thing:  I took two long, old rca cables and cut off the ends, connected each one's ground and signal to a light switch and then housed the switches in an old fat animal kingdom book.  I'm pretty sure that the cables I used are shielded... pretty sure i know what that means.  Since the reverb switches on and off just fine, I figured the tone thing must be with the amp and not the switch.  Where are you going with this?  Thanks for any help at all

[Anonymous]

I'm assuming a 190L is similar to other Sunn Tube amps with reverb.

A shielded cable has a braid or foil wrap around the center conductor.  The shield should be grounded.  This is important for the reverb switch as what the switch does is grounds the output of the reverb unit / input of the reverb recovery transistor.  Noise can be picked up by this lead if it isn't shielded.

There isn't a common definition of a harsh tone.  

Since you say it goes away with the reverb on zero and seems to become more harsh when the reverb is turned up, there's not much that can cause that action except the recovery transistor or the reverb pot.  Since you aren't complaining about a lack of reverb, I would put my money on the pot first, the transistor second.