Big muff diode selection switch pops

[runmikeyrun]

I have toggle switches to select between different clipping diodes in my muff gain stages.  However, they pop when switching with the pedal on.  Any thoughts on how to reduce that?  I'm drawing a blank. 


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[robthequiet]

How do you have them wired up?

[Mark Hammer]

It's not the diodes popping.  It's the caps in series with those diodes, that have nowhere to drain off when you monetarily lift the path to go between this and that set of diodes.

Happily, there is a very simple solution.  If you have two sets of diodes in one or both clipping stages, put diode pair A in series with diode pair B in each stage.  Your toggle/slide switch should have its common connected to the junction between diode pair A and pair B.  In one switch position, the switch bridges/shunts diode pair A.  IN the other position it lifts that bridge and bridges diode pair B. 

When bridged in the manner described, the "other" diode pair is effectively out of circuit, but at no time is the path that allows the feedback caps to drain off ever broken/lifted.

That should, in theory, cure your popping.  If, for some reason, you went nuts and decided to have 3 or more sets of diodes in a given clipping stage, that's going to require more thought and time than I have to offer today.

[runmikeyrun]

DPDT with a pair of diodes soldered on the outside lugs and the center lugs going to the circuit where the pair usually sits.


Ham fisting my way through one build to the next since 2003. 

[anotherjim]

Another way to do it is to leave diodes in the usual place in the board, but only fit the ones with the highest forward voltage there. Then you only need to switch an alternate lower voltage set in parallel circuit across them. 1 SPST can add one selection. An SPDT on-off-on can add one of 2 alternate sets giving you 3 flavours.

In high gain conditions, I don't think you can entirely avoid some switch noise, but as Mark describes, always having a complete circuit path whatever the switch state minimises the risk

[runmikeyrun]

That's a great idea Mark, and also yours Jim.  Thanks!  I'm gonna give that a shot next time I have a chance to work on it.


Ham fisting my way through one build to the next since 2003.