Power filter and popping

[Stratomaster]

Hello,
     I built a booster pedal using a power filter (220uf and 100ohm resistor).  I believe this is causing popping upon activation.  Is this possible?  Also, once disconnected, the pedal will still light up the LED presumably discharging the power filter capacitor.  The pedal does not pop when shut off, only when activated.  Since it's a booster with crazy high input impedence, wouldn't a pulldown resistor rob the circuit of signal?  I've checked the wiki on popping, and it looks like the pulldown resistors have got to work otherwise I'm SOL.  Thanks.

[d95err]

Hello,
     I built a booster pedal using a power filter (220uf and 100ohm resistor).  I believe this is causing popping upon activation.  Is this possible?  Also, once disconnected, the pedal will still light up the LED presumably discharging the power filter capacitor.  The pedal does not pop when shut off, only when activated.  Since it's a booster with crazy high input impedence, wouldn't a pulldown resistor rob the circuit of signal?  I've checked the wiki on popping, and it looks like the pulldown resistors have got to work otherwise I'm SOL.  Thanks.

There is no need for a crazy high input impedance. Anything more than 1 Meg or so will only add noice without any benefits. If you *really* need a crazy high input impedance (e.g. if using a passive pietzo pickup on an acoustic guitar), you can simply use a crazy high pulldown resistor.

Hmm... about that LED thing... are you by any chance switching power on and off when switching between bypass and on? (That would very likely cause a loud pop).

LEDs can also cause pops when powered on or off. Checkout the LED de-clicking article at www.muzique.com (in the Lab notebook). Try disconnecting the LED and see if it affects the problem.

[Brian Marshall]

how do you have the switch wired?

[Stratomaster]

I'm using the output jack to switch the power on and off.  I have the entire pedal wired up almost exactly like offboard wiring #5 from tonepad.
http://tonepad.com/getFile.asp?id=76
The only differences are that I used the output jack for the power switching (I have a tight fitting pedal board, and it's the last one in line), I split the power out from the dc jack to the LED and a low pass filter that outputs to the effect board.  I will try disconnecting the LED to see if that helps.  Thanks for the advice so far!

UPDATE: Removing the LED from the circuit had no effect on popping.  It is still there.  Will try large pulldown resistors next.

*UPDATE 2* Large pulldown resistor did nothing in the input and helped a little on the output.  I left the output pulldown in the circuit and removed the input.  Also, I added the LED filtering circuit just for kicks, and it seems to have helped a little too.  The popping is still there and very apparent.  It's just not as bad as it was.

[d95err]

The output pulldown resistor should not be large (high resistance). The output impedance will be fairly low, so 100k or even less should be fine witout affecting tone.

Just as an experiment, try using a really small input pulldown resistor, like 50k. This will cause some treble loss of course, but at least it will give you an idea of wheter that's where the pop is caused. If that cures the pop-issue, try successively larger pulldown resistors until you find a good compromise between tone and pops.

It would also help if you told us what pedal it is (or presented a schematic if it's your own design).