Relay Switching & Routing Without Pops

[pyreweb]

Hello,

I am just wondering if there is a consensus on the best way to build routing systems for guitar effects with as little popping artifacts during changeover as possible. Are the artifacts usually so loud that simple relay switching is not recommended? Or does using devices to ramp the levels up and down quickly alter the sound too much, and could they be bypassed once at maximum without simply adding further popping noises?

Many thanks.

[notnews]

I've been thinking a bit about this too..

I've been a standard 3PDT bypass stomp user for a while. I just started looking into relay switching but I'm concerned with latency and reliability/longevity.

What does everyone use to bypass/engage their effects? A relay daughterboard? Standard DPDT/3PDT?

Pyre, do you use relay switching exclusively? How do you like it compared to more traditional switches that don't require the extra circuitry and components?

[pyreweb]

I am afraid I can offer no knowledge of it myself. I have only recently started building pedals and have yet to fully complete any. My issue is that my rig is entirely MIDI-controlled, and I would like the effects to be mounted in a rack with the amplifier rather than on the floor. As such, remote switching is a necessary requirement for me.

In theory, I do not see why a relay switching system should offer any more of a popping sound when engaging or disengaging than a hardware 3PDT solution. Both disconnect the signal momentarily while the contacts change, if there is a difference then I would expect the time disconnected to be less when using a relay, and so in theory the pop should be quieter. I also suspect that while using relays would be more complicated, it would work out cheaper than using a 3PDT switch.

I have noticed from looking through the pedal guts image thread that some people on here do use relay switching from time to time. I would think that there would be a slight time delay, but probably less than the variance of the average musician's sense of where the beat lies, so less of an issue than pressing a switch fractionally early or late. But that is all my own conjecture, with no practical evidence to back it up.

Some commercially available pieces of gear do use relay switching for some things, for example the amp control jacks on some Boss multi-effects units. While there is the tiniest delay with this, it has never caused audible problems for me, or added popping artifacts to the sound. But then I do not know if these are simple on/off relay equivalents of DPDT switches or if they have some ramping off and on of volumes to smooth out the sound.

I am hoping that someone here knows more about this than I do.

[Muadzin]

I use the Uber relay switching system from THcustoms in Germany. It's a DIY board which you can buy from Thomas with a full kit, so no having to source those pesky relays, microcontrollers and optocouplers. Most of the kit is regular through hole, except for the optocoupler, which is SMT. Switching is done via a normal SPST momentary switch.

For my pedals I still use 3PDT switches, or the occasional DPDT switch in case its buffered. but as my pedal board is huge I needed to create a looper to keep the tap dancing to a minimum. Most of that could be done with normal 3PDT switches, some of that can only be done that way as it involves A/B switching, but I had also need for some stereo switching. As I like my delays, reverbs and harmonizing to be in stereo. For some strange reason nobody seems to have come up with a DIY stereo switch so I had to reinvent the wheel. First try was using a 4PDT switch wired as a dual millenium switch. Which worked, but I had pops. Which is highly annoying when you're activating a delay, so it led me into exploring relay switches. Everybody on the Madbean forum suggested that Thomas from THcustoms is THE relay expert and he suggested using two Uber boards hooked up to one SPST switch.

So I tried it and it worked. Of sorts. There were times that the switches worked counter to another, one on, the other off. Thomas suggested that I removed the microcontroller on one of them and do some trickery and that seems to have done the trick. It's still not perfect. I do seem to experience something, not a loud pop, but I can notice it when I activate the stereo loops. But this might also be related to some weird impedance thing going on in my loopers. It probably needs bigger minds then me to completely figure it out, maybe someone could give me the email addresses of Bob Bradshaw and/or Pete Cornish?

Anyway, I've installed some more Uber relays in my switching system. I don't think they're perfect but neither are mechanical 3PDT switches, which will probably break down a lot faster (10.000 stomps if you're lucky is something I've come across). If only I could find a way to use them in a A/B configuration as well then just true bypass or not I'd be a happy camper. As I said, I don't use them in regular pedals, as I don't think I'll be stomping on them 10.000 times before switching them for some other flavor of the month. Except for my wah pedals. I've modded my crybabies to true bypass but a 3PDT or DPDT switch just doesn't click so well as the original switches Dunlop was using. Something height related. A SPST momentatry switch is however exactly the same as the switches Dunlop uses, plus I now get to have a LED as well. Win-win!

There are other relay switching systems out there. I think there's a vero layout as well, THcustoms also has simpeler versions, 1776 has one too (I'd try it but I would have to order the relays from Mouser so f*** it), I've seen a few others as well here and there (Banzai, Monte Allums), although those are drop in SMT boards.

[Silver Blues]

I really enjoy using relay bypass systems and have tried a few but am still testing for the optimally functioning design. I'm planning on putting my findings into the Library when I'm finished. What I can tell you now though is that I've used AMZ relay bypass boards (from the time where he had a dedicated bypass board and now that he just has a generic DPDT board that can be used for bypass switching) and the simple Schmitt trigger system Mictester from FSB came up with. The AMZ ones work quite well, but I preferred the dedicated system to the configurable one although the configurable system works fine. It's just a bit expensive ($14 including shipping to my address just for the PCB) so unsustainable. The Schmitt trigger works OK but unless you use a PCB it becomes a bit unwieldy. I've drawn up a verified vero for this system and the corresponding FSB thread has ready to transfer PCB layouts. The only issues I have with it is that in its basic configuration it doesn't have a guaranteed state (i.e. you don't know whether it will default to on or off upon loss of power), and so the one I built defaulted to on (like, when I plug in power the pedal is engaged) which is a bit annoying. The switching action however works quite well as long as you don't machine-gun actuations. There is a way to implement guaranteed state but it involves using another trigger and a few more parts so would make a vero too big to be useful. I'm also looking to try out the OSH Park "Andy Relay" (once I get some relays for it) and another microcontroller-based bypass system similar to the AMZ one but at far less cost (which looks quite good). For what I hear, the Paulinthelab system is simple but has some noise issues even when including the required but forgotten flyback diode (although the reports are kind of variable).

It's a bit jarring to hear the crude thunk of a 3PDT once you've tried the soft-latch switching. It feels very refined and precise, and I haven't had any popping in my soft-latch-equipped pedals.