MidiREX -- DIY MIDI loop sequencer


I’d really like to get one of these, but I would have to use it slaved externally. Any news if the sync bug was fixed in the firmware? Any easy way to get an enclosure?


I could not reproduce the external sync big described above – everything works as expected here. You can order the case from Ponoko or similar service using design files referenced above.


Oh okay, I just thought that’s what you were talking about above when you said it was a firmware bug that was down on your list, priority-wise.

I’m trying to figure out the case stuff, how much it would cost, etc. Do certain files take certain materials? Or how can I open them to find out the material size?


@cs1729 The issue looked like the firmware bug and it still looks like one, however I could not repro it no matter what i tried, and static code analysis did not reveal any obvious problems. Will be glad to look at it again if someone provides environment and steps to repro.

Unfortunately i’m not really involved with case design, hopefully @altitude would chime in and provide the details.


all my cases are for 3mm material (of your choice)


Thanks. So if I want to make one that looks like the matte black one above, then I use the oled file? What is the oled window file for? It’s also asking for a size (p1, p2, p3), what do you select here?


The OLED file has the display below the front panel with a window to protect it. You would only need to use that file if you have an opaque case, otherwise you would use the clear (which has no window). The standard case has a cutout for the display. All the cases are P2 size except the window file which is P1


nice device, any video around … to see the groove for chords, bass … bie


It’s aliiiiiiiive!

need to clean off pcb and didn’t solder the led’s till I figure out case (didn’t get spacers : | ). Midialf next. @kvitekp sort of blew my mind when he suggested using them together midialf > midirex. Makes so much sense!


also finished my build longer ago, did some custom paintjob on it as looking inside on electronics was too distracting… would really love to have a function to trim recorded parts, like noodle around several bars and then keep the best ones.


@g_borovcak – “a function to trim recorded parts” – like in “remove everything from beginning to this point” and “remove everything from this point to the end” ?


is this possible as it would be super useful exactly as you describe it


Hi everyone.
(this was a silly question, now resolved)
I hope this is an appropriate place for such a question.
I recently managed to get hold of a midirex second hand and have updated to the latest firmware.
I was wondering if anyone else had experienced a similar to mine.

All works well until recording a fourth track. Whenever I do, 2 notes that i haven’t played are recorded right at the start of the pattern.

It doesn’t matter what order I record to the tracks. Whichever one is last gets these ghost notes. If anyone has any thoughts regarding this I’d really appreciate an opinion.



Sounds strange. Never seen this before. What are those ghost notes? Are they always the same or just random?



Thanks for the speedy response Peter. I’m using the unit along with a nord Stage and I just did a factory reset on the synth and I no longer seem to be having the issue. I think the keyboard must’ve been doing something it shouldn’t have been. Nothing to see here.

Great work by the way. Really nice bit of kit.


Yeah, doing a device reset was what I wanted to suggest to do. Good to know it helped.

I’m not sure using this forum to support MidiREX customers is still OK, so if you have any other problems, please contact me using email found at the MIDIRex ordering page here: https://midisizer.com/midirex/ordering-midirex/