Perplexed by pops

[Electron Tornado]

I built an overdrive based on the Smash Drive and Grace Overdrive. It sounds great, but it will pop when the footswitch is pressed. I removed the LED from the circuit and the pops continued. I tried adding pull down resistors at the output as well with no luck. Using an audio probe I found that I was hearing pops at the point where switch S2 is connected to the JFET, Q1. I don't hear pops at the gate of the JFET, however. The footswitch is a blue 3PDT with the word "CLIFF" printed on it.

Since I have pull down resistors on the input cap, what could be source of the pops?

Below is a schematic and a gut shot. (The gut shot likely won't be any help, but everyone likes gut shots.)

[R.G.]

I built an overdrive based on the Smash Drive and Grace Overdrive. It sounds great, but it will pop when the footswitch is pressed. I removed the LED from the circuit and the pops continued. I tried adding pull down resistors at the output as well with no luck. Using an audio probe I found that I was hearing pops at the point where switch S2 is connected to the JFET, Q1. I don't hear pops at the gate of the JFET, however. The footswitch is a blue 3PDT with the word "CLIFF" printed on it.

Since I have pull down resistors on the input cap, what could be source of the pops?

Below is a schematic and a gut shot. (The gut shot likely won't be any help, but everyone likes gut shots.)

Mother Nature is a stickler for details. She stubbornly ignores any efforts you make that don't fix the actual problem.

Lack of pull down resistors and LEDs are not the only source of popping. In fact, pull-down resistors are band aids that prevent the real problem (input/output capacitor leakage) from being so annoying. Likewise, removing LEDs is a bandaid for the real problem, which is power and/or ground transient voltages caused by the sudden change in current when an LED is switched.

I'm not really sure where to look at your problem. The schematic you referenced shows no bypass switching at all, no 3PDT, so it's hard to figure out what is happening. Maybe if we had the complete schematic we could figure something out.

There's lots of other ways to get pops. One good one is having a leakage path that puts dc voltage on the input or output of a pedal in amounts which normal pulldown resistors can't pull hard enough to make negligible.

[Kearns892]

Have you checked the FAQ and Wiki?

[Electron Tornado]

Mother Nature is a stickler for details. She stubbornly ignores any efforts you make that don't fix the actual problem.

Lack of pull down resistors and LEDs are not the only source of popping. In fact, pull-down resistors are band aids that prevent the real problem (input/output capacitor leakage) from being so annoying. Likewise, removing LEDs is a bandaid for the real problem, which is power and/or ground transient voltages caused by the sudden change in current when an LED is switched.

I'm not really sure where to look at your problem. The schematic you referenced shows no bypass switching at all, no 3PDT, so it's hard to figure out what is happening. Maybe if we had the complete schematic we could figure something out.

There's lots of other ways to get pops. One good one is having a leakage path that puts dc voltage on the input or output of a pedal in amounts which normal pulldown resistors can't pull hard enough to make negligible.

R.G.,

Thanks for your reply. I checked for any DC leakage on the input cap and found none. I have a family commitment this weekend, so I will post a schematic with the switching and LED included next week.

What are some examples of the leakage paths that you mentioned in your last sentence?

[sevenisthenumber]

change the switch.

[pravudh]

try to pull out input resistor 1.5m
I found some schematic don't need  pull-down resistor as  proco rat that i were done.

sorry for my english.

[sevenisthenumber]

I can 90% promise its the switch.... Ive had cliff switches do this due to over heating.