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.
