Reverb mods made

[MarkB]

Bob

Have you seen the TUT reverb? K. O'C. talks about ways of dealing with reverb noise.

No I haven't. I'd like to

Email addy?

[Bob-I]

Bob

Have you seen the TUT reverb? K. O'C. talks about ways of dealing with reverb noise.

No I haven't. I'd like to

Email addy?

bob-ingram@patmedia.net

Thx

[glasman]

Actually, I decided to try reducing the gain first. The 2 extra components, the coupling cap and series resistor look good, but it would require I change my layout. I'll try lowering the first return load resistor to 22K, then the second to maybe 47K. I believe that should address the reverb balance.

Bob, I was going over that lack of coupling cap and I think there could be some serious potential problems.

Looking at the plate of the second recovery amp I am guessing that there is somewhere around 190 volts on the plate. If you follow that back in the circuit to the relay it is going to put 160+ volts on the Clean Master Pot and OD level pots. If you turn the master or OD to zero, that 160+ is going straight to ground through the pot.

Put the amp in Clean D mode and measure the DC voltage on the wiper. Also try it in OD mode and measure the OD level wiper to ground, I bet you will see a pretty high voltage there, of course this is just my 2 cents.

Gary

[Bob-I]

Actually, I decided to try reducing the gain first. The 2 extra components, the coupling cap and series resistor look good, but it would require I change my layout. I'll try lowering the first return load resistor to 22K, then the second to maybe 47K. I believe that should address the reverb balance.

Bob, I was going over that lack of coupling cap and I think there could be some serious potential problems.

Looking at the plate of the second recovery amp I am guessing that there is somewhere around 190 volts on the plate. If you follow that back in the circuit to the relay it is going to put 160+ volts on the Clean Master Pot and OD level pots. If you turn the master or OD to zero, that 160+ is going straight to ground through the pot.

Put the amp in Clean D mode and measure the DC voltage on the wiper. Also try it in OD mode and measure the OD level wiper to ground, I bet you will see a pretty high voltage there, of course this is just my 2 cents.

Gary

Yes, it's over 180V, that explains the scratch on the pot. Coupling cap going in.... thx.

[glasman]

Yes, it's over 180V, that explains the scratch on the pot. Coupling cap going in.... thx.

No problem.

Gary

[Bob-I]

In another thread the "too much reverb" issue came up. Gary suggested using a dwell control or voltage divider on the input of the driver amp.

I tried several things today. First a 470k / 470k divider which only dropped the reverb a little, so instead of having the reverb control on 1, I could put it to 1.5

Next I changed the divider to 220k/820k, better but still not exactly right.

Finally I took a 500k mini pot and soldered it in. Yes the load should be 1M but I don't have a 1M pot small enough. This seems to be the trick, a dwell control is necessary. I'll source out a small 1M pot but for now the 500k is staying in.