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Oh yeah! Looks good! I have been working on similar stuff, just now and then, nothing serious yet. I'm building one, but not sure yet it's gonna have midi, but then again, it would probably be stupid not to! Does it work well?

hey, thanks !

It works really well, i'm also happy with the menu handling on the LCD. I've added a relay board with ULN2803, which need documentation.

For me MIDI is very usefull because I mostly command the pedalboard with automations from Ableton Live. The footswitches are only use when practising new songs ;)

I'll soon share my code project based on MIOS.

cool.

What kind of relays are u using? I have some thoughts about switching noise - like noise from connecting / disconnecting the FX pedals into the chain. How do you handle this?

 

My thought was to make a digitally controlled mute circuit at the end of the chain - that is - before signal enters amp or DI box. And mute the output for the split second it takes the relays to switch...

 

Have a strong suspicion that circuit for this muting or other way to do it can be found in schem for several of the common stomp boxes out there. Especially thinking of the boss tuner - which I know can do silent mutes.

I've read a lot of information from various website projects before choosing. A lot of information came from a french collaborative project of www.techniguitare.fr They made a similar project from wich i inspired, and adapted it to the midibox and add some features like buttons switching, and grouping...(to be detailed)

 

I'm using Omron G5V-2 for audio switching and G5V-1 for relays/buttons switching. They are driven by an ULN2803 for efficient switching.

These relays have been proven to work great on audio switching by the users who built the above mentioned project. So after building it myself i can confirm :

The relays do work silently !

Most of the audio clicks come from the pedals themselves when they are connected to the audio path. So it is important to verify, especially for non-buffered pedal (true bypass), that it exist some resistor on the input to absorb the generated clicks. I had problems with a EHX mini Qtron and I had to modify it. All other buffered pedal worked without problem for me.

 

Also from what i've read and understood the ULN2803 (see the picture of relays board in this album) is giving the relay a kind of voltage boost when switching to guarantee fast transistion, and thus less rebound. Too much boost would shorten the relay life, just enough would help. I'm sure that many highly priced commercial products do use the same mechanism. 

As all drawing I've seen to reduce these noises, are acting on how the relay need to switch, I don't know about any other improvement "after" the relay.