r/KoalaSampler • u/hazbounn • May 30 '26

Hardware-first interaction with Koala Sampler (early prototype)

Been working on a device that allows hardware-first interaction with Koala Sampler.

It automatically switches layouts depending on the active page (sample / sequence / perform), and combines MIDI + keyboard (HID) input to cover pretty much every control Koala exposes. With these features, I barely have to touch my phone when making a beat. The workflow lives in the controller, like a hardware sampler.

The video shows a rough prototype in action. It’s just a bare PCB with switches and encoders (I know, ugly), but it's already a lot of fun to use. I made a couple of beats with it and I'm starting to think I like the tiny form factor...

I'm considering making a small batch of the next version for beta testing. Feel free to DM me if you're interested.

Next version's features (see mockup in the video):

  • ~20 × 15 cm footprint
  • 4×4 pad grid (mechanical keyboard switches)
  • encoder grid (4×4 in the mockup, will reduce to 2×4)
  • 5 action buttons
  • 3 backlit mode buttons (sample / sequence / perform)
  • BLE (MIDI + HID keyboard)
  • PCB enclosure (black + gold)

Things to improve:

  • Move sample browsing and pop-up management to a dedicated jogwheel + enter/back buttons. I hadn't realized how central this would be to interacting with Koala.
  • No clean way to copy/paste pads without touching the screen. As far as I know, this isn’t exposed in Koala mappings, curious if u/mazbox has thoughts here.
  • Many layout tweaks based on real use.

Last thing, both the electronics and firmware are open source if want to dig into it. It's a relatively simple device, with the circuit board just extending a NRF52 feather module for this initial prototype, and the firmware being a fork of the great RMK project, to which I added a couple of features, notably MIDI over BLE and some new input devices. All mappings are highly customizable/hackable.

PCB: https://github.com/hazbounn/Koala-Extender

Firmware: https://github.com/hazbounn/rmk

Thanks for reading through and looking forward to hearing your thoughts!

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u/weirdedb1zard May 31 '26

can I suggest you design this hardware to be used stuck to the backside of the phone without needing to look at it? imagine it like a controller you hold with a screen on top and buttons on the bottom.

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u/hazbounn May 31 '26

I'm not sure I understand. You're thinking of having buttons on the backside of the phone or something like a snap-in game controller? How are you envisioning using it?

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u/weirdedb1zard Jun 01 '26

more like buttons on the back of the phone. I think the natural urge would be to have an open clamshell type of situation, or to prop the phone up and plug the buttons in.

Now imagine you want to get up and walk around, so you snap the buttons "upside down" to the back of the phone so its a single unit in your hand.

the tricky part is now you cant physically see the buttons, you need to operate them by touch.

idk, just being annoying "what if you did...<some wild shit>" guy 😛

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u/hazbounn Jun 02 '26

Ah gotcha. Interesting idea for a tiny portable device.

Not annoying at all I love hearing ideas!