Remote switching

[DutchMF]

Say I want to build a huuuuuge box, housing a couple of fx that I'd like to run through the fx-loop of my amp. Said box would be positioned on top of the amp, and I would like to be able to switch the fx on and off from my pedal board (hence the remote switching), but if necessary also plug it in front of any other amp and still be able to control them, sans the remote control. My brain says relay-based switching, but maybe there is a different, simpler way of doing this? Any tips?

Paul

Sorry if I'm not making much sense, I'm on one of those 'really-excited-about-something-I-just-thought-of!!' trips....

[jkokura]

Relay switching and midi.

You can operate a relay using a switch, or by sending a remote triggering signal via midi. It may be complicated, but it certainly is doable by DIY means.

I think Thomas might be a good resource for you. He's got the Pedal switcher project. You can also look into PedalSync, which is designed to do something similar I believe.

Of course, you could just go with a pure midi setup and get a ground control and a rack.

Jacob

[RobA]

I just happen to be working on the schematics for a different way as I read your post. I wouldn't say it's simpler, but it does have an option to not use relays, which to me is simpler. It also doesn't use CMOS switches, which have their own problems. I'm not quite ready to expose it publicly just yet, but if you want to see what I'm thinking and if it would be useful to you, send me a PM and I'll tell you what it does and send you schematics.

[soldersqueeze]

I just happen to be working on the schematics for a different way as I read your post. I wouldn't say it's simpler, but it does have an option to not use relays, which to me is simpler. It also doesn't use CMOS switches, which have their own problems. I'm not quite ready to expose it publicly just yet, but if you want to see what I'm thinking and if it would be useful to you, send me a PM and I'll tell you what it does and send you schematics.

I love mysterious posts like this 

[RobA]

I didn't really mean for it to be all that mysterious. I just haven't breadboarded and tested the final schematics yet. So, I guess I'll just say what the idea is and then put up links to schematics when I get them tested.

I wanted to be able to put say 3 small effects in a 125B box and have only 1 foot switch. So, that pretty much took out relays as an option. I was working on using CMOS switches/multiplexers, but they have issues with bleed through and some possible distortion issues. Then I came across the JRC/NJM2121D switched op amp. Problems solved. So, that's the heart of it.

I then wanted to be able to program the switching so I could have a set list programmed in say, where hitting the switch once would move to the next setting/combination in the set list. So, the control section is based on AVR processors.

Then I went kinda nuts and decided it would be cool to be able to put say 8 effects in a 1590DD  . So, that brought up the idea of using MIDI and or remote switching. So, right now I'm in the process of breaking each of the components out into little modules that can be mixed and matched. That also means that the idea would work with using relays and CMOS switches to do the actual switching in addition to using the 2121D's.

[jkokura]

Like.

Jacob

[artstomp]

...this type of switching is what Marshall Valvestate series amps used to select channels...i.e...clean/overdrive...M5201 is the opamp used...JRC2120D/JRC2121D i think is its equivalent...normally open sw is utilized to activate the opamp...

..good thinking RobA

..artstomp

[RobA]

Yeah, this is how I first came across them. I was searching for a source for the low profile jacks and came across a thread on a Marshall forum where someone was looking for replacement jacks for a Valvestate amp. Someone else was asking for an op amp to replace the switching op amp in their amp which got my interest because I hadn't seen a switching op amp before. So, I did a web search and came across the JRC parts.

For anyone interested in how the bypass works, I've linked a couple of images below of the switch control and the buffered bypass section. The switch control takes 0 to 5V logic level input from the microcontroller. I've tested the bypass with some pretty loud, obnoxious, noisy effects and seen no bleed through. Of course, it is a buffered bypass, but using any good op amp, I haven't experienced any tone suck. And for those pedals that hate buffered bypass, the control logic will work to run a DPDT relay as well.

I'm currently testing using a transistor input buffer because that'll be more convenient in some circumstances.

The idea is that you could either put this bypass directly on the effect board, use a separate control board, or put a whole set of the bypass circuits on one main PCB for a bigger switching system. The controller/brain includes outputs for post filtered power including Vref.

[DutchMF]

Thanks for the tips guys! I've been giving this a lot of thought, and I might, or might not go for it, but it sure is a thing I'll keep in the back of my mind.

@Jacob: I'm fully aware that your suggestion to go MIDI is probably the easiest and most fool proof, so if all else fails, I might try that. And I'll check out the stuff from Thomas, I've yet to take an in depth look, but it sure looks promising!

@RobA: Looks very interesting man! I'd love to see where you take this, I'll keep an eye out for progress reports!!

Paul