Getting pop noise - vox wah mod to true bypass

[Trick]

Hi, I've ordered a kit and installed a true bypass and dc power jack with led to a vox v847 wah. Unfortunately when switching the pedal on and off there is a loud pop sound which i know is inherent when going true bypass. I did try many things already. I believe the led is the culprit, when i disconnect it from the circuit, pop noise goes away and pedal is still functioning. I tried adding the pull down resistor in the circuit at r1 and ground and also tried on input and output jacks. this was through the help of who i bought this from, which he was very helpful but i didn't solve this. He also provided me another way to wire the switch so it grounded the input. I also tried adding a 390 ohm resistor in line with the positive side of the led with the original resistor and a cap in parallel from info i found on another site. This also did not help. I tried a cap i had laying around the smallest i had was 50 pf. it was suggested to try a 10 to 20 i believe, but i think that going higher should have definitely worked.

If anyone can think of what i can do to fix this, i'd appreciate it.
thanks for your time.

[Jazz P Bass]

Can you post a drawing of exactly what you are talking about.
Which part of the circuit is the LED wired to & how are you powering it.
Here is a FIS link to a V487 true bypass.
Link: Google Image Result for http://www.freeinfosociety.com/electronics/schematics/audio/pictures/voxva847.gif

[mikespi8]

Dude!

Run a red wire from the positive battery wire to a 4.7K resistor, then to one leg of a grounded 10uf capacitor, then to a 390ohm resistor, then to the anode (positive leg of the LED.
Then run a black wire from the cathode (negative leg) of the LED back to the lug of a 3DPT that shares a ground with your circuit input wire.

[mikespi8]

Could you share that wiring diagram?
I did a mod on a V847 today. This is the second one of these I have done.
I must not have remembered from the first one...everything works except the clean sound.

[Trick]

I am going to post the info i have soon. Been busy and haven't had a chance. thanks for the help and look forward to your solutions.

[Trick]

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[Trick]

above is the link to the other way which was suggested I wire it. which i believe is supposed to ground the input. hope it's enough info.

[Trick]

put a 1M ohm resistor at R1 to ground and also tried with capacitor (again tried using 50pf since it's the lowest value i have) between the led resistor and 390 ohm, one leg of cap to ground. I noticed pop was less when running power for led straight from the dc jack rather than using R9. It's still an issue though.

[Trick]

realized that was calling for micro farad. went out and got a 10 uf and 22 uf. still getting pop. wish i had another switch but everything is turning on and off correctly. also, when i disconnect led from circuit, it is basically making the same popping noise. I tried the 1 meg over the input and output jacks and still the same.

[Trick]

anyone have any ideas what else could be going on?

[Robert M. Martinelli]

Don't know what's going on, but the wiring diagram you posted seemed "wrong" to me (the LED and Audio circuits should be kept separate).

This is the way I've implemented a "true bypass plus LED" on a Wah I have built recently (it works flawlessly).

Hope this helps

Best regards

Bob

[Trick]

hey Robert, thanks so much for that diagram. I think that did it! There's still a noise when switching as with any true bypass pedal, but i added a 1 meg ohm resistor and that helped it a bit. I tried the cap mod but did not hear any difference, as the led is not causing any noise, so i didn't add it to the circuit.

thanks again for the help here. glad the frustration is over.

[Robert M. Martinelli]

Glad to have been able to help, and yes, the 1 Meg resistor can be useful in some cases, though my wah works perfectly without it so I didn't feel the need to add it.

Cheers

Bob

[gavin_rossdale]

I don't know why everyone nowadays is obsessed with true bypass.

[R.G.]

I don't know why everyone nowadays is obsessed with true bypass.

They have been obsessed with true bypass for decades. It's not just nowadays.

What people don't realize is that there are better ways.

True bypass is the solution to two problems we (musicians) don't have any more. It solves the issues of tone sucking when bypassed and running out of battery in the middle of a performance. Tone sucking in bypass can be cured easily enough by a (well-designed!) buffer on the pedal input, and batteries are busily going the way of the dodo because of high prices and the low cost of good 9V adapters.