MidiREX -- DIY MIDI loop sequencer

New DIY MIDI loop sequencer project materials are published here .

First production run boards are expected to be available on Jan 25th. They are going to be white with black silkscreen legend.

Most of the components are familiar to builders of Mutable Instruments DIY products. The build is very similar to Shruthi-1 Digital Board, however MidiREX is easier to build due to the lack of I/O serialization.

1 Like

One for me please

Well done!

Im in!!

@fcd72 – Hey Frank, hopefully you won’t let it run naked, can we hope for a case?


It probably goes without saying, but this is a fun device, for sure! As usual for Mr. Kvitek, the build process and use are both quite straightforward and logical.


Would it be possible to order this AND a MidiAlf (and chips) without increasing shipping fees ? (I’m in Europe)

I’ll take one…

From what I’ve read about this thing, it can record incoming midi on multiple channels into one “track”, so when the track plays back it outputs notes on both channels when in Omni mode - is that correct? Does it send all the notes in a track out one channel when you set the track to a MIDI channel, or will it just drop notes that aren’t on that channel?

Edit: Just read the manual and it looks like the answer is yes and probably…

I’ll take one!

I’ll have one…and a case.

As written elsewhere: I take one too.

Oh, it is on! In for one please.

Me too, one please.

@dubtoms: sure, MidiREX and MidiALF with MCUs can be shipped together for the price of larger item (MidiALF) shipping.

@borfo: yes and yes. Here’s how it works:

1. MidiREX processes incoming MIDI events on the channel it is set to. All other channels are ignored and passed to MIDI OUT as is.

2. When recording, MidiREX stores events with their original channel (that would be the channel MidiREX is set to).

3. When playing back MidiREX sends track events out overriding their channel with MIDI channel the track is set to unless the track channel is set to OMNI, in which case events are sent out as is with the original channel they where recorded on.

4. When merging tracks, MidiREX essentially plays back both tracks’ events into the target track, so if source tracks have different MIDI channels, resulting track will contain events on different channels as well. During playback, these events’ channels will be overriden with track’s channel unless it’s set to OMNI, in which case single track will play more than one channel.

In fact, it’s very common to bounce related tracks into one to free up a track: for example, you recorded drums, bass, pad and lead lines on tracks 1,2,3,4 then merge drum and bass into track 1 to free track 2 for more arrangement.

Thanks - so it only records one channel at a time then.

Sounds like a pretty fun device - looking forward to playing with it. I’ve really been having a great time with my MIDIalfs, by the way. They’re great little sequencers once you get familiar with the interface.

@borfo – yep, MidiREX records one channel at a time. Gotta keep things simple: connect a controller keyboard to its input and switch between 4 target sound sources on the fly.

MidiREX plays really well with MidiALF, they complement each other in a nice way.


Want this and MidiAlf CV and MidiBud also.