Rangemaster - true bypass click despite 2 "pull-down" resistors

[yeeshkul]

I added 1M resistors to the both input and output, but still have very loud click when turning my Rangemaster clone ON (DPDT switch - 9pin type - true bypass+diode). One my friend told me that the click has to be there because i am using battery switch via input stereo jack. I have no clue what to do. If anyone can help me ... there is no click when turning off. No other effect was connected - just guitar, rangemaster and amp.

[MetalGod]

There was a thread in the last day or so regarding status LEDs causing the loud popping - do a search.  I believe Jack Orman has some info on his website about this.

[yeeshkul]

I found a solution on Jack Ortman's site, but it doesn't seem to work at all  . The pop is definitely caused by the LED since there was no pop when i cut the LED off. I am sending a picture of the wiring around the main circuit. Please can anyone help me or maybe some of you can find a bug in wiring. The capacitor "delay" solution is a part of the picture.

[R.G.]

There is a design problem inherent in using a stereo input jack for switching power on. All of the effect power, including that of the LED, goes through that wire. The LED current going through the wire resistance causes a voltage drop that is added to the signal because the Rangemaster circuit, like many others, has no input common mode rejection. When you suddenly change the LED current by switching, there is a sudden change in the small voltage across this wire. The circuit amplifies this because it cannot tell that it's not signal, and you hear a pop.

This is a different mechanism for causing a pop from the one that pulldown resistors cure. That is why pulldowns don't help.

To fix it, you have two choices. You can either (a) make the change in current happen slowly somehow, or (b) arrange the LED current so it does not go through the input signal reference ground wire. Or both, I guess.

I personally like using the input jack ground wire to turn on a PNP transistor or P-channel MOSFET on the effect board that switches on the + battery voltage. The battery can then be permanently wired to the effect board and power turn-on is done by pulling an HFE-times-smaller and relatively constant current through the input ground wire. This cures the pop in almost all cases.

But there is room for creativity here, too.

[slacker]

I know it's probably not related to your problem if you've narrowed it down to the LED but your pulldown resisters are in the wrong place. They need to be between the in and outs on the circuit board and ground to work. They are there to send any leakage from the input/output caps to ground when the circuit is bypassed, if you put them on the input/ouput sockets they can't do their job because they're not connected to the circuit.

[yeeshkul]

Guys thank you very much for your answers! Now i have a few good solutions i guess.