I’m really pleased to say that my AudioFreeze module has won the Music Hackspace DIY instrument competition. I didn’t build it to enter the competition, it just so happened to be running at a similar time, but I’m super pleased to have won, especially as the other entrants were pretty cool.
Got to start thinking of what to work on next. I’ve got a few of the boards left, so it will probably be based around Teensy and Audio Shield again. I’ve start using Audio Mulch to experiment with some ideas for a signal chain. Will update when things start to come together.
I’ve added the Gerber files to GitHub so anyone can build the module if they like. As a disclaimer this module should be seen as a prototype. IT HAS NO POWER FILTERING OR SHORT CIRCUIT PREVENTION, if you plug the ribbon cable in the wrong way you may damage the board and potentially your other modules. Also your case must supply 5V power (some don’t). As this was my first PCB I wanted to make it as simple as possible. I’m merely making it available as a resource for people who want to make their own boards. If you do build your own I’d love to see it. Please tweet me @scolar any pictures or videos!
Finally got around to putting together a little video of the AudioFreeze in action, now with 8-bit option for longer loops. Updated source code is available here
To be able to mount my AudioFreeze PCB in a modular case I needed to craft a fascia. I decided to use laser-cut acrylic. I haven’t found anywhere in the UK that does bespoke Aluminium cutting, and, due to a kind friend, I had access to a laser cutter! I created a vector image in InkScape, a free, well-featured vector art package. It does have its drawbacks though, it’s not particular user friendly. I haven’t found an easy way to show the centre of objects, so I ended up making guidelines to show me, and hiding them in another layer.
I came up with a design involving snowflakes, and I wanted these to be in a different colour. I covered the acrylic in masking tape, and once it was cut I painted over the top with several layers of thin acrylic paint. It wasn’t entirely successful, the paint didn’t fill the etched areas quite as well as I’d hope, but I’m still very pleased with the final result. One downside of using acrylic is that it’s 3mm thick, which seemed slightly too deep to be able to get a nut on the jack sockets as not enough of the barrel protruded. The Aluminium panels from the Thonk – Music Thing kits I’ve built were thin enough not to have this problem.
After a few hours of soldering my PCB is populated and it works! There was no way of knowing for sure without building it, and as this was my first PCB I had some doubts, but thankfully it’s all good. The LEDs and corresponding resistors have yet to be added, I wanted to wait for the facia before soldering these in place to get the height right It can be powered either via USB or from the 5V line on the Eurorack connection.
First version of the firmware is up on GitHub. Current version has only one mode. Top red button captures a loop of audio. Pots from top to bottom control:-
loop window size
loop window position
pitch
mix with incoming audio
Bottom red bottom currently doesn’t do anything, but my plan for the next version of the firmware is to have multiple modes. I’m thinking of a mode which has a volume based threshold for triggering the sampling, and possibly a granular delay mode. Also the ability to sample in 8 bit (rather than 16 bit) for increased loop time. LEDs are also unused currently, they will probably show active modes.
Next up is the fascia, hopefully laser cutting that this week so expect pictures soon.
My first ever PCBs have arrived, possibly the first of many? Can’t wait to get the first one soldered up. After that I need to design the Eurorack panel, current plan is laser cut acrylic. Will post demos as soon as it’s made! Thanks to Hackvana for fabricating them, a highly recommended service!
I made the most of this Bank Holiday weekend by making up some contact mics. I’ve used mini-jacks so I can use them with my Mikrophonie module, and soldered the shielded cable directly onto the wires that come attached to the Piezo discs. I’ve dipped them in Plasti-Dip, a weird gloopy coating, that should mean they are now waterproof (hydrophones?). I had to dip each one about 4 times to get a decent amount of coating, hopefully that hasn’t deadend the sound too much. Expect videos of me freezing them in ice and recording them de-frosting (the sound designers equivalent of watching paint dry?)
So, I’m ready to progress with my AudioFreeze project, and move from breadboard prototype to permanent module. I didn’t relish the thought of transferring the circuit to Vero board, it would be possible but fiddly. I toyed with the idea of fabricating my own (see http://www.instructables.com/id/How-to-Etch-a-PCB/), but a friend made me aware that you can get very low (10 or so board) runs of unique PCB designs factory manufactured for around £25, so roughly £2.50 a board.
I downloaded Eagle Light Edition, PCB CAD software. It’s free for non-commercial hobbyists to use (with a maximum board size 100mm x 80mm, which is fine for my needs). To say it has a steep learning curve is an understatement, its UI is rather non-standard, thankfully I had someone very patient to mentor me and get me started (thanks Jason!)
It took me a couple of iterations, but the board design is now finished, let’s hope it works! Just a 3 week agonising wait for them to be delivered from Hong Kong!
I’ve started work on my first Eurorack module. As my experience with analogue electronics is rather limited, and I’m a coder at heart, I’ve decided to base it around Teensy again (as I did with my Midi Pedal), so the functionally can be programmed in software. I’ve also added the Teensy Audio Shield, this supports 16 bit, stereo audio, rather than the 12-bit mono DAC on the standard Teensy.
My first module is the AudioFreeze, inspired by Mutable Instruments’ Clouds. It’s functionally much simpler though. It continuously samples incoming audio into a buffer. When the button is pressed it locks, or freezes the buffer and continuously loops it. You can then adjust the size of the looping window, and move the window inside the buffer with 2 pots.
