Embed Axoloti within existing MIDI hardware (sequencer, keyboard, controller)

#2

I have a similar idea...
I opened my E-Mu XBoard25 keyboard and found out that there is a perfect place with definitely enough space to implant an Axoloti, namely above the battery compartment.
Therefore, it seems very attractive to me to make a real, stand-alone synthesizer of this device.
I'm not yet sure if I make the connection via MIDI or USB-MIDI, and how to unite the power supplies. And some more mechanical considerations are to be made, like a back plate design. But it should be relatively easy.
Maybe I can even retain all the original functionality as well.

I think we could collect and share here our findings about the suitability of all sorts of MIDI devices, couldn't we?

What I think would be very attractive for implanting is the Behringer BCR2000. Does anyone here have one and could check if there is space left inside?

"Axolotify your MIDI device!"

#3

This is quite amusing and definitely a sign of the times. Normally people strive to add midi controll to their ageing keyboards and synths. Here you're trying to add a synth to an aging midi controller. :smile:

I have a mate at the gym who got out of the synth scene 10 years ago. He's astounded by what I tell him about what's possible for next to know money these days. It's an awesome time for synthers.

#4

This is really unbelievable!!!! The Xboard 25 is exactly what I am planning to build. I bought a second hand one last month for €5, opened it up and discovered the space underneath the battery compartment. When you take out the battery holder, but leave the door, you can access the Axo to change connections to the GPIOs. On the front panel is room for several pots, switches and leds. And it has 16 midi pots already! And aftertouch.
One mechanical question: can I mount the Axo upside down, or will that cause heath problems?

#5

Not a problem whatsoever

#6

Hi All,

I have a midi keyboard I picked up from goodwill that has 5 pin din midi out. I'd like to embed the Axoloti within this keyboard so it can run as a standalone synth, while retaining the original functionality of the midi keyboard.

I'm thinking all that I have to do is wire the midi out from the keyboard right to the midi in of the Axoloti. Do I need to do anything to protect the Axoloti from other things that I might plug into this midi keyboard, or is it fine to just solder the midi pins to each other?

Thanks

#7

Dunno about protection but the Axo has a little header behind the Midi IN. I'd solder in a box header in there and using breadboard wires instead of hard soldering them together.

#8

A similar topic can be found here: https://sebiik.github.io/community.axoloti.com.backup/t/adding-axoloti-to-existing-midi-hardware-sequencer-keyboard-controller/720

#10

@Miles, I agree with @janvantomme pretty much the same topic, so Ive combined them.
(altered the title of existing topic to reflect the idea better)

I do think its a really interesting Idea, it will be interesting to hear about projects,
and also what people find are suitable donor machines :smile:

I think something with a velocity sensitive keyboard, 4 pots, small... perhaps with built-in speakers... and runs off batteries - could be a huge amount of fun.
@johannes, do you think you could run axoloti of replaceable/rechargable batteries, or do you think eats just going to eat them up in 5 minutes !?

#11

I think embedding Axoloti into a midi controller can be really nice. In fact I have an old Studio Logic/Fatar master keyboard waiting for a transplantation.

I'd recommend using one of those external powerbank batteries with usb output made to recharge a smartphone or tablet on the road. Even small ones should last several hours.

#12

Oh ffs. Now I need to redesign to include a battery! OMG the scope creep never ends!!

#13

Thanks for merging, saw that other topic but didn't realize it was so similar.

Mainly what I am worried about is that the midi in on the axoloti would be wired to the midi in on another synth, but that very well might not even be a thing to worry about.

I think this: http://www.amazon.com/Reveal-MusicStar-Multimedia-Keyboard-Software/dp/B00WHIRRH2 is pretty identical to what I picked up from goodwill.

I think I'll just go ahead and solder it up and report back here what I find.

#14

And one more here :wink:

#15

From what I've learned since posing the initial question, is that you cannot simply "splice" together MIDI signals. If you wire the output fro the keyboard directly to input of the Axo, you MIGHT get away with being able to connect an additional instrument. However, if you attempt to directly wire the input of the keyboard to the output of the axo, you will likely not be able to use the axo output.

Basically, you cannot simply merge MIDI information by wiring together a simple 1:1 splitter or merger. There are simple circuits online that could work, but I've not done too much research beyond discovering it likely won't work as simply as directly wiring in's to out's and vice versa.

#16

A simple solution would be to configure the axoloti as "midi through", meaning you directly send the midi input through to the output in your patch, but also split the signal in the patch for your Axoloti Synth.

I am wondering if any of the gpio pins are/can also be configured for midi I/O (like it used to be on the STM32 dev board?), so that the axoloti had several midi I/O ports?

#17

There is an old unmaintained (sorry) patch that shows how to read/send MIDI on gpio in archive/tests/io/extra_midi_input.axh . But it will likely need some fixing before it works, as this was made long before release. I'd appreciate if a developer in the community could have a look at this.

#18

I'd appreciate if a developer in the community could have a look at this.

Thx, found it, fixed it, will upload as soon as i have tested it with other hardware. :slight_smile:

And here it is:
hug/midi_io/extra_midi_io.axp

#19

:slight_smile: Here it is:


Not any internal cabling yet...

For 3D printing, download STL files here, and for modifying/re-using, download Sketchup design files here. And here is a link to a DIY instruction:

#20

That looks very nice, like it was made to fit there!

#21

This is a cool project!
Can you share how you wired the keyboard to the axo midi in?

#22

Currently it is only connected externally by a USB cable at the Axo USB host port. This provides both MIDI input from and power supply to the keyboard. I am not yet sure how I could make the connection internal without sacrificing the keyboard's USB connectivity to a computer.
Using the MIDI input DIN connector would have been easy too, but I wanted to keep it reserved for additionally receiving MIDI clock.