EXH holy grail mod issues

[knealebrown]

Hey guys, tried some ideas for mods with my EXH holy grail reverb. This is what i wanted.

A switch to have 2 preset reverb levels, standard reverb level and a secondary reverb pot control.

Heres what i did, disconnected the original pot from the board and connected that to a 3pdt switch connected the pads from the board to the center lugs of the switch then connected another pot (same value as the original) to the remaining lugs. so i can now select between two reverb levels.

The problem is that i now get a pop when i use that switch, my question is probably going to receive an answer that is obvious to some but 'How do i stop that pop'.

I know 'the pop'  question gets around a lot so im presuming its the old problem of DC ofset but whats the practical answer to this particular issue?

As always any help would be great as this added feature would be great for me.

Kneale

[Taylor]

Kind of hard to say without a schematic, not sure if one is available, but...

It's digital, of course. One common digital control method is just a voltage divider between +v and ground, and the wiper to an ADC input. In this case, what you're switching between is 2 DC levels, so it's not a matter of some pesky DC accidentally being there - you're deliberately doing that.

One thing you can try is to put an RC lowpass between the output of the switch and the ADC input (or the pad that the wiper was originally attached to).

Like this - these values are just defaults, you'd need to play with the resistor:

http://tinyurl.com/2vgmcuz

Now, all of this is assuming a voltage divider. Other digital stuff uses the pot as a variable resistor, and in that case I suspect the solution would be much hairier. Make sure you confirm how the pot is being used before doing the RC lowpass thing.

[ilcaccillo]

Hello,
did you ever fix your pop issue?

thanks