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Treble Bleed Pop

Started by effectsbay, April 05, 2010, 12:02:28 AM

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effectsbay

Man.. I'm getting SOOOOO tired of dealing with pops in the pedals. I just recently added a treble bleed circuit (option via toggle). Treble bleed circuit is .001uF 63v cap and 100k resistor in parallel on my 1M volume pot on the box. Since I added that in, I get a pop when the pedal is engaged (regardless if treble bleed circuit is engaged or not). I'm assuming that it's bleed off of the cap, just curious what's the best way to deal with this? I have the resistor/cap soldered from the switch to lug 1. To try a pull down resistor, would I need to have it after the cap/resistor but before the toggle? Let me know if I'm missing something else that is obvious.

So to clarify, treble bleed and 2PDT toggle switch added.. pops occur. No toggle, no treble bleed circuit.. no pops.

Thanks!
hank

GibsonGM

Do you have a 1M resistor to ground after the treble cap/resistor? That might help.  Wire it so it's always to ground (before the switch); it's so large, it shouldn't load the signal down.  Don't know if I'd want that on a switch, but if that's how you like it, that's cool. 
BTW, your treble bleed is going from the signal to the WIPER of the pot, right?  It's supposed to...not just to jump over the pot completely....

~MP
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effectsbay

Hello! Thanks for the reply.

I'm sort of following this diagram:
http://www.offsetguitars.com/forums/viewtopic.php?f=6&t=189&p=66031

The actual treble bleed example is this:
http://www.aronnelson.com/gallery/main.php/v/WGTP/Treble+Bleed.GIF.html?g2_imageViewsIndex=1

Resistor/Cap in parallel across lug 1 and 2. The switch connects the two. The cap/resistor is on the switch and connected to lead to lug 1 of the pot. I'm wondering if I should break this out to a vero board instead of on the switch. Thought it would be nice to have it right there.

Thanks!
hank

GibsonGM

I don't think it being on the switch is an issue, it would do that wherever it is.
Are you using an LED to signal on/off? That would be the real culprit, if you are!

1)  I think you should try a 1M resistor to ground from either end of the cap and resistor (if that makes sense).  This will drain away built-up charge when you're just playing, and keep the thing from popping (maybe).  There shouldn't be any DC on there, but that is usually what causes this.  You do have an output cap at the circuit output prior to this, right?
We'll figure it out!
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effectsbay

This is on my breadboard. I get no pop if the toggle switch is out. If I put the toggle back.. I get the pop. The breadboard does have LED and 3PDT footswitch and it's quiet with out the toggle (and treble bleed circuit). I feel pretty good that it's the toggle causing the problem. I tried to clip a 1M resistor between the treble bleed circuit and ground.. and no change.

Thanks!
hank

GibsonGM

Search for "LED pop".  There's a cap to ground trick that will cure that. It's the LED doing the popping, not the cap/resistor!  Try opening the LED circuit and see if the pop is gone.  Then you can do the little cap trick to ground (On the LED section, not the treble bleed). 
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GibsonGM

Look at this, and copy the idea for your LED - bet it will eliminate that pop >;o)
http://www.muzique.com/lab/led.htm
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effectsbay

I'm not sure if it's the LED. Remember.. this doesn't pop when I remove the toggle/tb circuit. LED is still in line for the board with or without the toggle addition. Pop only happens if the toggle is there.

Thanks!
hank

StereoKills

#8
Quote from: GibsonGM on April 06, 2010, 10:11:17 AM
Look at this, and copy the idea for your LED - bet it will eliminate that pop >;o)
http://www.muzique.com/lab/led.htm
I've used the second method there with great success on a Rebote circuit.

It's possible you need to add something similar for the tb cap line to prevent it from discharging all at once.
"Sometimes it takes a thousand notes to make one sound"

GibsonGM

If you have an LED indicating "treble bypass on or off", it is 99% likely that it's the LED switching on that is popping.  The sudden demand to charge (or discharge) a cap will cause an audible 'pop'.   
The only other thing I know of doing would be to have a large cap (1uF or bigger) always switched in, and switch off to the smaller one, so that you're not abruptly changing levels.  This shouldn't pop, which is why I am saying it's the LED - they have a VERY fast turn-on time, consistent with a pop.   Just break out the 2 resistors, add the cap, and check it out....
BTW:
You still haven't said whether you have an output cap BEFORE this whole deal...you should, something big (10uF, 22uF, etc).  What you're describing is DC switching noise.  A cap before will block the DC, and won't interfere with the transfer of frequency (1 to 10uF being big enough to pass about all the guitar signal).   Please draw what you have going - without actually seeing this, it's really hard to analyze and find a solution!!  ;o)  Specifically, how are you wiring the DPDT? You only need a SPST unless you're using the LED to indicate on/off. 
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GibsonGM

This is what I am envisioning that you have now:

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