krüe
:: avrsyn
avrsyn
overview
avrsyn is a digital synthesizer designed by
Jarek Ziembicki.
It uses an Atmel atmega16
and a 16bit discrete r2r DAC. PCBs and kits are available from
Elby Designs.
I used a stock board but swapped the original atmega16 and 8MHz oscillator
for an atmega32 and 16MHz oscillator.
sound samples
enclosure
I've built my board into a desktop style case made of sheet aluminum
with poplar end panels. Here is a diagram/drilling guide for the front panel:
avrsyn-panel.ps
I didn't label the pots and switches because I think of the avrsyn as a
"poor man's chameleon".
The hardware is very generic: just a microcontroller with digital and analog
inputs, and an audio output. It is easy to write code that changes the
synth architecture.
Here are some pictures of the completed case:
software
I've been steadily adding features to the original avrsyn code. It's very
much a work in progress, but you can download what I have so far. Remember
that this code assumes an atmega32 running at 16MHz. The current version
is avrsyn-2007.12.22.asm.
features
- 62.5kHz sample rate
- two 24bit dcos
- waveform data selectable at assembly time
- saw, sine, square, triangle
- sine to saw morph
- adjustable detune
- octave transpose
- two operator frequency modulation
- noise source
- three selectable filter types
- original one pole iir high and low pass
- state variable with low, high, band, and notch outputs
- moog transistor ladder low pass based on
this paper
- arpeggiator
controls
Since there are not enough controls available on the front panel, some functions
are controlled via MIDI continuous controller messages.
pot |
parameter |
0 |
lfo frequency |
1 |
lfo level |
2 |
dco b detune |
3 |
dcf cutoff |
4 |
arpeggiator threshold |
5 |
arpeggiator rate |
6 |
portamento |
7 |
dcf env level |
|
cc |
parameter |
$30 |
dca env attack |
$31 |
dca env decay |
$32 |
dca env sustain |
$33 |
dca env release |
$34 |
dcf env attack |
$35 |
dcf env decay |
$36 |
dcf env sustain |
$37 |
dcf env release |
$38 |
dco a level |
$39 |
dco b level |
$3a |
dco a waveform |
$3b |
dco b waveform |
$3c |
|
$3d |
|
$3e |
dcf resonance |
$3f |
fm depth |
|
switch |
parameter |
$00 |
xor distortion |
$01 |
|
$02 |
|
$03 |
dco b enable |
$04 |
dca mode (gate/env) |
$05 |
transpose (down/up) |
$06 |
transpose dco a (down/up) |
$07 |
transpose dco b (down/up) |
$08 |
lfo mode (dco/dcf) |
$09 |
lfo wave (tri/squ) |
$0a |
dcf keyboard tracking |
$0b |
|
$0c |
dco a noise |
$0d |
modwheel enable |
$0e |
lfo keyboard sync |
$0f |
lfo random enable |
$10 |
dcf type (lp/hp/band/notch) |
$11 |
$12 |
arpeggiator enable |
$13 |
|
|
references
- http://www.jarek-synth.pl/
- Jarek Ziembicki created the orignal syn8535.
- http://www.vacoloco.net/synths/
-
Paul Maddox had the idea to update the design to an atmega16
and have a run of boards made.
- http://elby-designs.com/avrsynth/avrsyn-about.htm
-
Laurie Biddulph took the project over from Paul and offers pc boards
and full kits.