True bypass popping

[Mexxx]

Hi everyone!
So, I built a true bypass Big Muff, I added the resistors for pulling down the current, I added the small mod for the led (muzique.com) and I still get the popping. Any suggestions?

[Mark Hammer]

The terminating resistors on any TB pedal operate under the assumption that it is the only pedal you are using, or that every other pedal used is also TB with the same sort of terminating resistors.  What is often overlooked is that when one uses a TB pedal with any other pedals that use electronic switching and, by so doing, forego the terminating resistor, use of a TB pedal can cause popping in the other pedal.

Here's the schematic for a Boss CE-2, a classic.  You can see that the input capacitor is not terminated, although the output cap is.  These pedals will pop when you first plug in, but once you plug in, all bypassing is done internally in a manner that does not involve that input cap.  Should you place a TB pedal in front of it, hitting the stompswitch will momentarily disconnect that cap's input before reconnecting it  There's your pop.

Even more perplexing to beginners is that if you had several TB pedals ahead of that Boss-type, and all except for the first one were in bypass, stepping on the first one would still cause a pop in the Boss-type.  As far as that pedal is concerned, true bypass for even 100 pedals in front are the same thing as a single piece of wire, and lifting that wire's connection for moment will produce a pop.

Can it be cured/avoided?  Absolutely.  The same way it is cured in TB pedals.  Just run a 1M or higher resistor between the input  and ground.  That way if another pedal temporarily disconnects from that input cap, the cap still has a way to drain off.

[Jdansti]

The terminating resistors on any TB pedal operate under the assumption that it is the only pedal you are using, or that every other pedal used is also TB with the same sort of terminating resistors.  What is often overlooked is that when one uses a TB pedal with any other pedals that use electronic switching and, by so doing, forego the terminating resistor, use of a TB pedal can cause popping in the other pedal.

Here's the schematic for a Boss CE-2, a classic.  You can see that the input capacitor is not terminated, although the output cap is.  These pedals will pop when you first plug in, but once you plug in, all bypassing is done internally in a manner that does not involve that input cap.  Should you place a TB pedal in front of it, hitting the stompswitch will momentarily disconnect that cap's input before reconnecting it  There's your pop.

Even more perplexing to beginners is that if you had several TB pedals ahead of that Boss-type, and all except for the first one were in bypass, stepping on the first one would still cause a pop in the Boss-type.  As far as that pedal is concerned, true bypass for even 100 pedals in front are the same thing as a single piece of wire, and lifting that wire's connection for moment will produce a pop.

Can it be cured/avoided?  Absolutely.  The same way it is cured in TB pedals.  Just run a 1M or higher resistor between the input  and ground.  That way if another pedal temporarily disconnects from that input cap, the cap still has a way to drain off.

I've got an electronic switching pedal that pops when TB pedals are in front of it. The pedal has a 10M resistor from input to ground. Is this too high of a resistance?  Is there a good chance that swapping it with a 1M would help?

[R.G.]

It's a bit amusing to me to see issues with true bypass keep coming up.

True bypass is not inherently pop-less.

[zombiwoof]

I was under the impression that the TB wiring scheme that disconnects the circuit board from the input in bypass helped with popping problems (with no need of pulldown resistors).  Interestingly, this is the way the vintage Fuzz Faces were wired.  I know that LED's can cause some problems, though.  I've wired all my wahs using this method, and no popping with them (though there are no LED"s involved in the wahs).  The wiring diagram is available at many pedal modding/building sites.

Al

[R.G.]

I was under the impression that the TB wiring scheme that disconnects the circuit board from the input in bypass helped with popping problems (with no need of pulldown resistors). 

A lot of people are. This is explicitly NOT true.

True bypass is pretty much the solution to problems we no long have; at least not the same problems that made it good back when dinosaurs roamed the earth. 

Interestingly, this is the way the vintage Fuzz Faces were wired. 

Yes. Also many others. Still, the pop/no pop characteristics are not a result of true bypass or not.

You might be interested in "The Technology of Bypasses" at geofex. It goes into this in a lot of detail.

[Mexxx]

So, I kinda got rid of the problem. What I did in the end was add the pulldown resistors, add the muzique.com led thing and wired it according to ggg.com diagram, where the input is grounded. Basically did everything i could find, and now there is no popping or buzzing or any other terrifying sounds Hope this will help someone. And thanks for all the responses!

[fuzzo]

More I build more I get bored with the wirring and the poping of tru bypass switching . The more annoying is that it depends of the pedal chain . The other thing is that blue dpdts are a nightmare to solder proprely , it's a massive time consuming . I totally understand why big brands use electronics bypass. It offers intelligent features as well, clickless switching and buffers !

The 1M (or higher) resistor don't always remove the popping noise