Mid Boost Pop

[ChrisM]

Got a mid boost switch that just adds a capacitor in parallel with the treble cap in the tonestack. The treble cap being that 250pF, 500pF or so small cap connecting to the treble control in most Fender Marshall tonestacks from the slope resistor.

Anyways the SPST switch just disconnects one end of the cap from treble lug 3. The other end of the cap is connected to the slope resistor.

Bit of a pop when the control is switched on.
Can I just add a large resistor (3.3M or so) from that end of the cap with the switch on it to ground? The reason I ask is it looks like a high pass filter then. Cap is 2nF and if resistor is 3.3M the cutoff frequency is around 25Hz. Im thinking this should be ok. Maybe make the resistor bigger and bring that frequency down even more...

Thanks...

[Jana]

Put a high value resistor across the two terminals of the switch.

[Gaz]

...which allows the cap to stay charged, preventing the pop.

[Structo]

Dumble uses a .002uf in series with a 390pf.
Then a 4M7 is attached between them to ground.

[ChrisM]

Yes I know, this is a different setup though. Paralleling the cap.

Will try today though...

[d95err]

Just put a resistor across the switch. 1M or so should do it.