Is mechanical true bypass switch popping just an inherent flaw?

[skiraly017]

This is specifically in reference to an LPB-1 build using the GGG layout. I'm not looking to discuss the Millennium Bypass or other switching options. I just want to talk about good 'ol 3PDT blue Taiwanese mechanical true bypass switching.

I've used the search button and read RG's article about switching. I've tried from a 4.7k to a 1M as my pulldown resistor. While the resistor did tame the popping a little, it killed the "feel" of the pedal in the process. While trying to fix this issue, I took a look at some boost/OD/distortion pedals I had and every one of them popped when engaging the switch especially as the volume and/or gain was turned higher.

So my question this...is this just an inherent problem with 3PDT switches and true bypass switching especially in any sort of gain pedal? Other than a pulldown resistor is there another solution or do I just deal with it?

Thanks.

Thanks.

[Paul Marossy]

Other than a pulldown resistor is there another solution or do I just deal with it?

As I see it, your only other choice is to use a Millenium Bypass or Joe Davisson's LED Trick (or similar circuit). I'm suprised that you have a pop in an LPB-1, that's not a really high gain pedal... 

[R.G.]

There is some popping inherent in every hard mechanical switch. This is due to the suddeness of the switch contact. If the switch contacts happen to touch when the signal is at a non-zero level, then there is a sudden infinitely-steep transition from the dry to wet signal, or viceversa. That sudden change can sometimes be perceived as a click.

However - it's really, really rare for it to be objectionable.

What you're describing is indicative of some other problem. Have you measured the DC voltage level on the dry and wet signals at the bypass switch? I would guess that maybe there's a DC level on either the dry signal, the wet signal... or the signal back out of the amplifier... that is causing the pop. All of these can cause popping that is difficult to control with a pull-down resistor.

Pull down resistors are there to control popping in the normal case, where there is no DC level out of the guitar (can happen with any on-board electronics), no DC level out of the amp (yep, some of them do) and correctly fitted, non-leaky input and output caps on the effect. They cannot stop pops when the conditions I listed are not met.

[Paul Marossy]

Yeah, it does sound DC doing something there. What are you plugged into when the pop happens?

[skiraly017]

I may overstated the pop. It's not severe and I can live with it. Certainly no better or worse than some of my OD pedals and I checked them all just to make sure. The OD's weren't home builds, they were a Reverend Drivetrain, MI Audio Blues Pro and a MI Audio Crunch Box. All exhibited a pop that got louder as the volume and gain knobs were turned up. The LPB-1 is the only effect in the chain during testing. Powered by either a battery or a Voodoo Lab PP2. I read RG's "Why does this ******* thing pop?" article. I'm going to try the 4.7k to ground on the PCB next build. When I was trying it earlier, I was just dropping it in in various places in the circuit to see if it would help.

As always, thanks for the help.

[Paul Marossy]

What's kind of weird is that some of effects will pop when used with certain devices but not with others. I never get pops when using my pedalboard with the amp I always use, though. I have noticed that delays can pick up the pop where you would normally wouldn't hear one otherwise. That's really about the only time I ever notice a pop.