Mittwoch, 8. April 2009

Modular Synth

It's been a while since i last posted something in this blog.. I haven't been passive in that time though. I started with something that every synth-diyist starts at some point: a modular synth! The first module is built was the PolyAVR, which is now rehoused to fit the modular rack. That was a nice start since i could already play chords with only one module installed. Then i added two analog vco's, a filter (yusynth minimoog filters, mixer and vca's (lower cabinet) and multiples. The upper cabinet contains two envelope generators MFOS, a LFO (alsoMFOS) and a voltage controlled LFO.

Mittwoch, 7. Januar 2009

new old site

dear readers,

Partly because of the drum synth project being more or less finished, partly because of missing flexibility i'll gradually move my content from this blog to my new website, be sure to check it out!!
if you have question you can always send me an email to - now comes a small riddle (because i hate spambots..)
fuerholz AT 'the abbreviation of Global Message Exchange'.' swiss domain identification (two letters)', should give 3letters, one dot and two letters after the @

Sonntag, 28. Dezember 2008

AVR-Based Synth

After finishing the Drumsynth Prototype i started another little synth project. It consisted in turning an atmega16 microcontroller in a simple 4-voice polyphonic synthesizer.
I've been working a lot with microcontrollers so i was curious to see if i could turn an atmega into a polyphonic synth. Another reason for this project was a lot of spare time at my dayjob since this project is much about programming which can be done ver easily in the office ;-)

By simple i mean that it only contains one oscillator per voice, no filter and a ADSR envelope per voice. Of course there are some other avr-based synth projects (,, in contrary to these projects i tried to focus on polyphony, with the aim of including it in a modular synthesizer.
What came out until now is a very cheap, cheap-sounding and cheap-sounding box. Technical data:
wave sampling rate: 31,25 kHz
resolution: 16bit
envelope (and possibly lfo) sampling rate: 244 Hz
midi: note on/note off
Extensions: basic wavetable capability, lfo

here is the video of this synth(sorry about the sound)

Sonntag, 14. Dezember 2008

PCB layouting

lots of thing have been going recently. I've started a new project: a digital polyphonic synth based on an atmega16 ic (pics and vids soon). I was looking for a good schematic and pcb designer software. After a long search and much hairpulling i finally decided to use an open-source package called gEDA. Although it has some small bugs it's much easier and less complex than many commercial options.
I've now (nearly) finished the layout of the sequencer master part. Here it is. I've noticed that (clever) layouting pcb's is a quite demanding task..
Please don't etch boards with that layout yet (that's why i didn't put the resistor values..) i have'nt checked and tested the layout yet

Donnerstag, 13. November 2008

Synthesizer Treffen

One of the most important personal goals regarding my home-built instruments is to make music with them, so i did recently at the swiss synthesizer meeting in zurich. It was whole an deeply satisfying new experience making electronic music in a large group (8 musicians). The largest part of the session was ambient stuff with very minimal beats. Coming originally from drone/stoner rock i really liked this slow and spheric, but not so hard-n-heavy part of the session, simply magic!!
Here a video of the session, i was there with the soundlab, electric guitar and, of course the drumsynth, in the video i'm playing guitar

picture and audio files can be found here , if you want to hear the sound of my drumsynth check out track 'Jam teil 8'

Mittwoch, 5. November 2008

Schematics (finally!)

Here they are, i put them on a real website as pdf's, currently without explanation. I hope they understandable and helpful. Since many people were interested in building the entire or part of the project i'll definitely work on pcb's and make them available on the net as well. Once working flawlessly i'll publish the source code for the sequencer part too. At the present state it still crashes from time to time but i'm working on it..

Montag, 3. November 2008

Beta Version finished

Hi there

The beta Version of my drum synth is finished!! Since the case is fully packed with electronics i will add midi-support and some of the optional stuff externally. It's extremely fun to play around, and, as i wrote in the first post in this blog, very intuitive and easy to use since i created this instrument exactly as i wanted is (withing the limits of my mechanical building capabilities of course).
Thats certainly not the end of this blog and my era of building synth's, i feel more it's just the beginning .. there are too many ideas spinning around in my mind. Anyway, currently i'm working on clean documentation of the drum synth and on PCB's. On idea of pusblishing the building process on the web was also to make it accessible for other people. For this i got some webspace where i will put the sequencer source code, schematics etc. Having it as pdf's is probably more usable than plain pictures... Please let me know if you're interested in re-building the project of parts of the project, if someone is interested i will start designing pcb's. I'm also willing to sell pcb's and programmed avr's ..

Here is the video of a first demo, unfortunately i turned up the reverb a little bit too much..