Pulldown resistors....

[danielzink]

I have a build that is giving me fits.
I had an issue with a microphonic cap - and resolved that.

Now though - the pedal is popping when engaged.

There is already a 2m drop down resistor utilized in the layout. Should I go larger than that ? How large an Rpd can be used until you affect the sound - or - does an Rpd affect the sound at all ?

Thanks, Dan

[earthtonesaudio]

The resistor provides a discharge path for the capacitor, so the output from the cap is at the same (ground) potential as whatever you're switching to/from.  This assumes that the thing you're switching to/from is also at ground potential, otherwise: POP.  So the pop may be coming from the next device in the series, if it doesn't have a pulldown at its input.  Check this first.


In any case, the larger value you use for the pulldown resistor, the more slowly the cap will discharge.  Try smaller values, not larger.

Also, the type of capacitor used makes a difference.  Aluminum electrolytics leak more than film caps or ceramic, etc. and will be more prone to popping.

[kurtlives]

Use 1M input pulldown and 1M output pulldown.

I would also try removing the indicator LED.


This build is not putting you in a Zen like state!

[danielzink]

Use 1M input pulldown and 1M output pulldown.

I would also try removing the indicator LED.


This build is not putting you in a Zen like state!

Can I do something fancy like put 1m resistors on the jacks ? across the tabs ?

Dan

[Cliff Schecht]

Yes, that is done in amplifiers all of the time.

[John Lyons]

If you put a 1M resistor across the in/gropund of the jack then you will be affecting the signal all the time
regardless of the bypass. You want to put the pulldown at the input of the circuit to ground instead.
This way when you are in (true) bypass you just have a straight wire from in to out with no circuit in
between.

John