2014-08-15

The Beginnings of the Eurorack

I decided to take the plunge and dive into Modular with a Eurorack setup. I figure that all I do is modify my equipment for control signals and chain them up, why not add in some equipment that is made to do that.
The case is a 9U rack case with 2 Tip Top Happy Ending rack ears with 2X uZeus power supplies.
The top 3U is just a blank panel. I used velcro secure the Volca Beats and Bass. The sync in/out on the Volcas plays really well with the modular's gating. The Beats has very usable White and Pink noise thanks to my earlier mods. The Bass (not pictured) is currently taken apart for investigation. I am determined to get the CV and gate outs for each of the 3 voices so I can make the Volca Bass a seriously badass sequencer for my modular. I've found a few points and am investing additional circuitry to make it happen. I've found the gate points, but the voltage needs to be bumped up from the 3.3V that the Volcas run off. Details to come.

Here are my current modules:
Pittsburgh Modular Synthesizer Box
Pittsburgh Modular Waveforms
Pittsburgh Modular Passive Multiplier
Make Noise Brains
Make Noise Pressure Points
TipTop Audio MixZ
Pittsburgh Modular Outs
Synthrotek Dirt Filter
Malekko VCA
4ms Rotating Clock Divider
4ms RCD Breakout
4ms Pingable Envelope Generator
Synthrotek Echo

I've already had a lot of chaotic fun with these guys, I have a DSI Curtis Filter on order and a Mutable Instruments Braids on the way.

Eventually, I want a Make Noise Wogglebug and René. We'll see about that.

I really like getting this guys going with the Arturia Minibrute and Korg MS-20 Mini. There is a lot of fun to be had with all 3. I use my Minibrute as a MIDI>CV converter too, along with being a great arpeggiator.


There is much more to come! Including new Eurorack module designs.





2014-07-20

Simple Sequencer Schematic. Used in MS-20 mini mods.

I've had a lot of requests for the schematic of the sequencer I used in my MS-20 mini mods. I've been very busy, but I finally drew them up all nice and perdy. 
The circuit is a super simple one based off the 4017 decade counter IC. The clock input can be from anything with a pulse like the MS-20's square LFO, Volcas, drum machines, ect. I didn't hook up the reset due to lack of space on the MS-20 mini's chassis. This circuit gives you a gate and CV output for fun step sequencing. 
The 4017 is powered by the 9 volts inside the MS-20. 
Here is a Larger Image.
I admit that this circuit is very rudimentary and additions can be made to add more features. You can add jacks to each step so you can change the length of the sequence using the reset line. So many possibilities. 
I added switches on mine so you can choose to engage or disengage the gate for individual steps for fun rhythms. 
I also want to add a portamento switch that engages a portamento between steps. I'll document this when it's done.
If you want to get really fancy, you can throw a microcontroller into the MS-20 and read off the MIDI from the MIDI port and get clock signals to MIDI sync you sequencer. Leave a comment with any fun additions you do. 



In other news, I have resigned from Ernie Ball / Music Man and accepted a job in San Francisco with Quirky. I want to get involved in the synth scene here. I am pretty sure it has to be bigger than SLO's. Let me know if you life in SF and want to make music or need repairs or anything. 

2014-02-21

Moog Circuit Bending Challenge 2014 Entry


The competition rules stated that the bend had to cost less than $70 dollars, run off 9V batteries, and be repeatable. Source code and schematics will be available via GitHub in the coming weeks (once I clean it all up)



I bent a Yamaha DD6 to mash up drum samples using an iPad.

I used an Atmel XmegaA3BU Xplain board as the brain along with an Intersil crosspoint switching matrix IC. The Xmega communicates with an iPad via USB by functioning as a class compliant USB MIDI device. There are 3 buttons on the board; an up, down, and enter button. When the device first powers up, it is in the "HOME" screen. The "HOME" screen also acts as a way of clearing a preset so the DD6 can go back to stock when using the device, by pressing enter when "HOME". Any of the 10 presets can be recalled by scrolling to them and pressing enter. The last position in the menu is a "RANDOM" setting which creates a random preset. 

The app on the iPad allows you to make connections on an 8X16 grid, which creates 3.4e38(!!!) possibilities. Using the iPad, you can save your preset to one of the 10 available preset locations on the device. With the iPad, you can also clear all the connections or make them all. 

I also added a sync out from the DD6. This sync allows me to clock an external sequencer or even a Korg Volca. 


Here are some of the videos:

This video is actually the last video, but it includes a discussion of the overall project and sound demos at the end. 

Going over the hardware.

The iPad app and it's code

XMega firmware code










2013-12-27

Inside the Volca Beats

As with the Volca Bass, I found no suitable room for a MIDI jack so I just broke out the labeled test point and will install a 1/8" stereo jack for the MIDI.








 



Inside the Volca Bass

Had a solid hour of fun with the Bass before I popped it open. 

I was hoping to add a MIDI jack to get MIDI out since it is clearly labeled:
I couldn't find space in the case to place a DIN jack so I am going to order a couple stereo 1/8" jacks to break out the MIDI that way.

I didn't do anything too crazy; just broke out the marked test points on the PCB

The jacks fit perfectly

Interesting that the SMD LEDs are on the other side of the PCB and they shine through holes






Used the ground point from the battery




Left an extra hole for the MIDI

 The jacks let me patch into both waveforms from all 3 oscillators, and the raw signal out of the VCO, VCF, and VCA.