DIY Project Recommendations


There are loads of other good ways to do this! I think 2 solid options are PiSound and Bela (maybe the new Bela Mini).

The benefit of PiSound being that you can just run the PD patch on linux, but there aren’t any analog inputs on the pi, so you’d have to use an arduino or something too. So it’s easy to run PD, but using a hardware controller might defeat the purpose of a standalone box (and using the arduino would increase the space requirements).

Bela would give you analog I/O along with 8 analog inputs (and there’s a multiplexing add-on to add way more inputs) with the caveat that I think it’s slightly less simple (but definitely doable) to run the PD patch. There’s a thread about Bela here.


Nice, thanks! A friend of mine just recommended I look at Bela, too.

I would ideally like to keep it a standalone box, that I could use on its own, or with others (e.g. with a SoftPop)


Also, could you explain how analog in/outs work? I’m not familiar with them, and the Holzer patch has a section ready for MIDI mapping. Could I do that via analog ins?


So on the Pi you have digital I/O - if you send a voltage into the pin above a certain level, the Pi treats it as a ‘1’, and if it’s below that level it’s a ‘0’. With analog I/O you can send it a voltage within a certain range, say 0-5V, and it can treat that as a number between 0 and 1 (the amount of numbers it can express depends on the resolution of the DAC).

The idea of all this being that you could wire up a potentiometer as a voltage divider and send 0-5V to whatever device you choose, and Pure Data would map that to the internal controls of the patch. If there’s midi mapping in the patch, a way to do it could be wiring pots and switches to an arduino (just had a look at the patch GUI, you’d have to have a think about the interface you’d want - especially with the patchbay), and have that send USB MIDI to a Raspberry Pi, which the PD patch can handle right out of the box. Equally, if you look at that link i sent for PD on Bela, looks like it wouldn’t take much time at all to use the adc~ object to control parts of the patch.


The new rebel tech box on kickstarter could be an option. It also runs gen~ code - would be interesting to compare max and pd runglers before you commit.


Gotcha. For the interface I was thinking an LED button grid. As it happens I’ve found the archived DIY Benjolin page on the old Casper Electronics site, so depending on how easy or not it is to get a PCB (and clone of the Yamaha chip), I wouldn’t mind a hardware benjolin instead. Albeit without the patchbay of the Holzer patch…


I bought a second hand Bastl ABC recently. It was a DIY and has a couple of problems - some channels let signal through regardless of dial position, and others have scratchy pots. I’ve looked at the back and see several bad solder joints. How easy is this to fix? I’ve not soldered much beyond piezos and simple PCBs before.


Touching up solder joints shouldn’t be a problem. I think Bastl put schematics online of the modules which makes troubleshooting easier. If touching up the joints doesn’t fix it you can take it to the Befaco workshop — Diego & Manu will help you out!


I’ve been trying my hand at a little soldering and finding it quite difficult. I want to figure out whther I’m doing something wrong, or whther the cheap soldering iron I’m using isn’t fit for purpose.

Basically my tip oxidises extremely quickly - and doesn’t seem to transfer any heat. I’ve tried tinning it wth a lot of solder, but don’t seem to be having much success. Do I just need to get some proper tip cleaner?


It’s likely your cheap iron. The second you switch you’ll see a HUGE difference. even going from a no name $5 iron to a known $25 iron will make a huge step.

I’ve had good luck with the lesser expensive weller irons and the SSVT soldering station. I’m now using the Hakko FX888D, at $100 it’s not cheap, but I’ve been using the same tip for 2 years, and it’s quality and precision are amazing.

with the cheap irons I’ve used with my students over the years (ahem, looking at you sparkfun, ahem) We’ve had nothing but problems and it’s impossible to keep the tips going for more than a few days.

I also recommend that you use a copper nest instead of a wet sponge, immediately when I did that, my tips started lasting a lot longer and oxidized less.

what iron do you have?


I am using this one - the amount of positive reviews gives me pause in thinking that it’s all the irons fault.

A copper nest is a great shout - I’ll pick one of those up first and see how I go.

Thanks for the help :slight_smile:


I had a student with one of those kits, and it did seem to be ok (on my 1 day assessment) :man_shrugging:. getting a non-water cleaning tool like the copper nest and a fresh tip is a good plan then you can see where that gets you!


I’m revisiting this idea. What Arduino would I need to achieve this? Presumably just ins for 8 (linear?) pots, and some way of controlling the patchbay.


Yeah I guess partially it depends on your implementation of the patchbay. There are a confusing amount of arduino types (even more if you factor in clones!), but off the top of my head, you’d probably get away with any of them.

If it were me I’d pick up an Uno R3 (real or fake) just because it’s a bit nicer to prototype with, and kind of handy to just have around. Once you’ve sussed out the programming and hardware connections, you could pick up something smaller depending on your space requirements, like a micro or nano.

What are you thinking with the patchbay interface? The best idea I can think of is little buttons and LEDs (something like a pocket operator but with through hole LEDs) or 2 of something like this? Guess that’s your job not mine :wink: Curious to see what you come up with!


I definitely agree with investing in a better soldering iron/ copper nest recc. Anything with an adustable temp makes a world of difference. Lead-free solder flows at higher temperatures than leaded solder-- around 750 usually is enough heat.

Also if you plan on re-soldering a joint or doing any rework, I recommend getting a solder braid or a solder sucker. Sometimes it’s easier to get a good joint when the pads are clean.

If you find the solder isn’t flowing easily onto the pads, try getting a solder-flux pen. Just a little flux on a pad will help a lot.


Thanks for all the tips regarding soldering. I ended up just getting a brass nest - and it solved a lot of my problems. I also used some different solder, which was thinner and a lot easier to work with than that which came with my iron.

I built a Bastl tea kick. It was very satisfying - I love learning new skills like this, because I suddenly feel empowered to take a part and mess with a whole new class of objects.


Hoping I’ve understood correctly:

Just trying to read back - if you’re specifically interested in building a MIDI controller, I’d skip all the Arduino boards (primarily because the one that would be ideal for this is discontinued) and just pick up a Teensy - LC or 3.2, but you’d be fine with an LC.

Why? Because the Teensy can be a native USB HID controller. Ie: you can tell it it’s USB-MIDI in the development interface, write a small amount of code (which can largely copy from an Example, I’d imagine - I forget what’s included in the library) to just map eight pins to eight CCs, and it’ll Just Work plugged into any old computer. (Pots are wired as voltage dividers - GND and 3V3 to pins 1/3, pin 2 to analog input on Teensy). If you want to interface buttons, you could wire some buttons to digital pins and have them pretend to be MIDI key events, which you pick up in PD.

The base Arduinos - Unos and similar - just can’t pretend to be USB HID devices without a whole pile of pain. (The Arduino Leonardo could, and it’s discontinued).

A Teensy LC is about £10? Also it’s far smaller than the duinos, and you can still develop in the little Arduino IDE. It’s what I’ve used to build all manner of midi controller or pretend-keyboards.

Sorry if any of that is vague; feel free to ask me about things that don’t make sense.


Excellent shout! Far better than what I was talking about with arduino

Thanks for pointing out the LC, I hadn’t come across it, and I think I bought a 3.2 when I was at uni so I remembered it costing a lot more than it actually does…


Can’t vouch for the quality, but on Sun 27th Aldi in the UK will be selling soldering stations with adjustable temperature. £20. Seems worth it.


I used an Antex XS25 yesterday at the Befaco workshop and it was really good I found. Just ordered one. Thin solder made things so much easier too!