Very simple midi signal interrupt stomp box?

[7enderbender]

Hello everyone,

This is my first post and after some research I felt this is the right place to look for an answer to my question.

Background info: I'm in the process of reworking my guitar rig which is really three rigs; my old stack/rack system, a more recent versatile combo amp solution (to save my back) and, well, also now a fancy combination of those two. I'm splitting the guitar signal with an A/B Y box and from there it runs into the looper of the old system and/or the combo amp.

Problem is that everything is controlled with one old midi switcher and programming doesn't always match up for all scenarios. To solve that issue I'm looking to build a basic stomp box that would simply interrupt the midi signal to my Lehle looper on occasion so that the manual selection of the two loops won't be overwritten by midi program changes.

I would think that this shouldn't be too hard to do. So the box would have a "midi in" and a "midi out" side and a stomp box switch to kill the signal from IN to OUT while providing a "OFF" position LED (or better yet one for ON and one for OFF). I'm thinking that I probably could just use the switch to interrupt one of the three midi prongs. But which one? Does it matter? And how to accomplish the two LED on/off solution?

Any pointers? Has this been done before?

Thanks

[moosapotamus]

Welcome to the forum.

I've never built any midi gear, but I do use midi.

Is this picture correct?



If so, it seems you could use two of the poles on a 3PDT stompswitch to break the connections to pins 4 & 5, and use the third pole to simultaneously alternate switching two LEDs on/off (ie, green/red).

~ Charlie

[Mac Walker]

I think Pin 4 is 5V, pin 5 is switched return (MIDI data).  Also I don't think the 9VAC referrenced above is not present in modern MIDI devices, I think this might be an older DIN connector standard.....

If you use a low enough power LED (very small) I think you could get away with switching pin 5 (MIDI data) with one pole off a DPDT, and source the center of the 2nd pole through a dropping resistor from Pin 4 (5V) to feed the red and green LED's off the top and bottom of the 2nd pole (negative of both LED's tied to common).

Let me know if this doesn't make sense....

Also, be aware that some of the diagrams floating around the internet may appear reversed, it is not always clear if the diagram is referring to the front or rear of the plug......

[amz-fx]

While it might work, there could be problems with just interrupting the midi signal, such as:

Let's say the midi controller sends a note-on command and then you hit the kill switch before the notes are through sounding. The midi synth (or other device) never gets its note-off command and so it continues to play indefinitely.  The same would go for other commands that have two parts to actuate/terminate.

One idea is to use a small micro that detects when you interrupt the midi signal, and it would then send an all-notes-off command to the midi output.

Best regards, Jack

[Digital Larry]

While it might work, there could be problems with just interrupting the midi signal, such as:

Let's say the midi controller sends a note-on command and then you hit the kill switch before the notes are through sounding. The midi synth (or other device) never gets its note-off command and so it continues to play indefinitely.  The same would go for other commands that have two parts to actuate/terminate.

One idea is to use a small micro that detects when you interrupt the midi signal, and it would then send an all-notes-off command to the midi output.
Best regards, Jack

I'd like to see a diagram of the system before commenting.  I agree that you don't just want to cut off a MIDI message at a random point in time.  It doesn't sound like there is any note data going through it though.  I still don't quite grasp the problem to be solved.

My honest suggestion is to (as you suggest) use a microcontroller of some sort, build a state machine in software that tracks the protocol requirements of MIDI, and makes well coordinated modifications to command flow or details in response to the push buttons.

[Mac Walker]

midi program changes.

I interpret this as not having any note on/off messages, in that the OP is only sending MIDI program changes, like from a MIDI mouse:



I think a footswitch would be equivalent to disconnecting a cord from a MIDI through device, I think you wouldn't do it while data is being transmitted (between songs, etc.)

[7enderbender]

While it might work, there could be problems with just interrupting the midi signal, such as:

Let's say the midi controller sends a note-on command and then you hit the kill switch before the notes are through sounding. The midi synth (or other device) never gets its note-off command and so it continues to play indefinitely.  The same would go for other commands that have two parts to actuate/terminate.

One idea is to use a small micro that detects when you interrupt the midi signal, and it would then send an all-notes-off command to the midi output.

Best regards, Jack

Thanks Jack,

After some research on this issue I found that this concern comes up. However, for me this is just for program changes. I'm a guitar player and all I'm looking to do here is to have the ability to take my Lehle looper (as in stomp box/rack loop) out of the midi control path so that program changes to other devices (prior in the chain) do not override manual settings in some cases.

I wouldn't step on in while sending anything. But thanks for bringing it up as this might be an issue for other folks who are sending more complex or continuous data.

[mister_midi]

Hi Guys,

I just wanted to let you know that I successfully built a midi signal interrupt stomp box:
For the box itself I bought a Orange guitar amp switch. Then I added two midi jacks, soldered a few cables, and removed the resistor at the LED.
The switch is just interrupting pin 5 of the midi cable, everything else (pin 2 and 4) is always connected.

It didn't cost much and just works. Of course, as previously mentioned by others, using it incorrectly may freeze some notes, but for most purposes you can avoid this problem.





Isn't it gorgeous?

Cheers,
Mr. Midi

[garcho]

I remember the first time someone showed me the Melodyne plugin. Blew my mind. Fix live recorded audio like it was midi.

I recently made a "MIDI channel filter" with an arduino. It takes in all MIDI data on whatever channel you dial in, then finds the channel nibble and changes it according to the output channel you dial in. It also can filter out or leave in start and stop transport messages. I have a MIDI controller sending data to a sampler that wants channels 1-10, and a monosynth that can only receive on channel 1. So this way I can send channel 16 (for example) messages to the MIDI channel filter device, change those to channel 1, and send it off to the monosynth, without interferring with the sampler (or vise versa). I don't always want the monosynth's sequencer to start when the sampler does, so I added the transport filter, too.

Does that seem like something along the lines of what you need, a MIDI message filer? The wiring/building part is easy. I can help with the code.

[aron]

Yes, with Arduino it should be easy to just look at the status bytes and filter out the program change. Or equally easy is to just stop the MIDI thru.