about popping signal noise

[hazenut]

Please help me.
I've made a landgraff Dod and modify.

http://www.matsumin.net/diy/jisaku1/Lg_DOD/Landgraff_DOD_sch.jpg

I've eleminated R18 10k.  
Therefore, I get more open and sweet tone!!
But, when the effect is turned on/off, loud popping noise occur.
Because of eliminating R18 10k, popping noise occur.
This popping also occur without dc 9v connecting.
How can I get solution with dropping R18 10k ?
So, how can I eliminate popping noise?

[armdnrdy]

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[hazenut]

Hi,

That is not ordinaly popping noise!

Of course,

I have already searched all data in this forum.

[armdnrdy]

Try a 1M resistor for R18.

[bluebunny]

Large resistor to ground before C2?

[induction]

Large resistor to ground before C2?

If it wasn't popping before he took out R18, then it is almost certainly popping at the output. An input pulldown of 1M or 2M won't hurt, but probably won't help either.  I agree with Larry, replace R18 with a 1M resistor and you'll likely get rid of the pop without removing the tonal improvement.

[antonis]

That is not ordinaly popping noise!

If you use an LED indicator, disconect it and have a try...
(maybe you need a RC switching delay for the LED..)

[MrStab]

if the tone is more "open" without R18, that makes me it was the low-ish value of 10k that sucked the tone to begin with.
as the other guys said, maybe 1M would be a good compromise. go lower if it still pops (but not if it affects tone too much).

not sure this would help the problem, but maybe replacing or following Q2 with a JFET or an opamp buffer could be useful, if those have a lower output impedance than the NPN and wouldn't be loaded down as much. i never use BJT buffers in my own circuits so i don't know too much about the output impedance of them.

[PRR]

> eleminated R18 10k.  Therefore, I get more open and sweet tone!!

R18 should not have any obvious effect.

This suggests something else is not as shown on that schematic.

[Ice-9]

I am going to presume that rather than a jack output straight after the junction of c11+ R18 there is part of the bypass switching. If so then removing R18 in itself won't cause a pop but depending what is plugged into after this can then pick up a Dc offset left on C11 and indeed pop. Anon true bypass pedal like boss types would be more prone to this.