Help with Popping!

[alparent]

I've built the Frequency Booster from Craig Anderton's DIY Projects for Guitars Book.
http://www.generalguitargadgets.com/pdf/ggg_ca_frequency_booster.pdf

It's working perfect, but when I switch between capacitor values I get popping.

I was looking at Matchbox project at runoffgroove.com http://www.runoffgroove.com/matchbox.html and they have a bunch of 5.1M resistor between the caps.
Is that to prevent popping?

My basic question is what can I do to get rid of the popping in my Frequency Booster?

Thanks

[Govmnt_Lacky]

I have run into this same problem with the Phase 100 and Mod-able Wah builds on GGG. I was told that a pull-down resistor needed to be put between EACH capacitor and ground. It looks like they just put the pull-down resistor between each cap in your example 

[PRR]

I can't read the Booster plan, but such schemes all have the same issue.

Look at the Matchbox plan. Omit the 5Meg resistors. The left end of each cap is at some DC voltage, here about 4V. The right end is at zero volts DC, WHEN connected to the 1Meg volume pot. The cap charges-up to 4V DC (on turn-on).

What about the other caps? Their right end floats. What is the voltage here? Undefined. Could be anything. With real-world caps and clean wiring, probably about the same as their left end. 4V on the left, zero V across the cap, the right end floats near 4V.

Connect the floating cap to the 1Meg pot. The right end drops from 4V to zero. POP! Since typical loud signals here are 1V, this POP is 4 times louder than loud.

If you turn-down and slowly turn through all positions, then you can switch with little pop for several minutes. You have put the 4V charge on every cap, and it doesn't bleed-off for several minutes.

If we could pull-down the floating ends, when idle, to where they will be in-use, there would be no POP.

We can't short to ground, that would shunt the idle caps across the source, which probably won't like the load. We need a resistor to "bleed" the charge.

The bleeder should be much-much smaller than the capacitor internal leakage. For modern film caps, the leakage is much higher than 100Megs. Values of 1Meg to 10Meg are suitable.

You can bleed each cap to ground. That still puts some load on the source. And it needs siz resistors.

If at-least one cap will always be in-use, you can bleed all other caps to it. Basically tie resistors across all switch throws. This only needs 5 resistors, adds no load on the source, needs no ground connection.

[alparent]

Thanks for the explanation PRR.

So 5M ..... 1M tie resistors does it make any difference?

I don't want to over think this......just wondering? 

[PRR]

> does it make any difference?

It depends a LOT on the circuit impedances, capacitor quality, and acceptable pop.

Just use 1Meg. Five each side of the switch.

BUT!

Is it THIS plan: http://www.diystompboxes.com/smfforum/index.php?topic=77739.msg644488#msg644488 ?

That should not be popping. Pins 1, 5, and 7 should be at the SAME voltage DC. Within 10mV 0.01V, which is not a large pop. POP! suggests you have a DC problem. Everything not at zero or +9V should be around +4.5V and all the SAME>