switching between cathode capacitors causes a Pop

[Dman]

I think this is a simple question but in my amp build I have two switches with a popping issue when I flip either switch for the first time after the amp is turned on.

The first switch is a bright and deep switch on the input stage cathode in the preamp section. It switches between two different capacitors. The other switch is in the output stage tubes and switches on a capacitor for more of a twang like sound.

When I turn on the amp the first time a switch, either switch, is flipped it causes a fairly loud pop. Every time after it has been switched at least once it no longer pops.

I'm guessing this is because at first the capacitors are not charged when they are not switched into the circuit and so it causes an initial pop . Any suggestions to fix this? I was thinking of putting a large resistor to bleed some voltage into the capacitors before they get switched into the circuit. Any other suggestions on how I can charge these capacitors before they get switched in while keeping the capacitors from affecting the circuit while they are not switched in?

Thanks

[tedmich]

maybe its because the cap IS charged? Add a bleeder resistor across the cap and see if it doesn't "pop" initially. What value is it?

[Enzo]

The cap needs to be charged. Put a large resistor like a 1 meg across the open switch. That will make the cap charge but the resistance prevents the cap from acting in the circuit. Then the switch shorts across the resistor revealing the cap to the circuit. No pop.

[Dman]

Thats what I was thinking

I was thinking to put the 1M ohm resistor across the switch so that the cap is charged when it is switched, wasn't sure if it would effect the sound quality or if there was another method or approach. I'll have to wait and see what the end results are. I am out of 1M resistors for time being will have to order some.

Thanks for the responses.

[d95err]

The resistor can be way lower than 1M. Anything from about 10k and up should work fine. Use 100k or so if you want to be really sure the cap is effectively out of the circuit.

[Enzo]

The value is not critical, just something fairly large.

I see this sort of question all the time, and my reaction is always the same. Wonder if it will affect the tone? In the time it takes to ask this forum, you could have tacked the part in there and found out already.