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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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 Posted: Fri Jan 08, 2010 7:57 pm Post subject:
Shruti-1
Subject description: My first DIY synth |
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Hey all,
6 months ago I set myself to design and build a simple mono synth, as a way of learning electronics, embedded systems, and more generally "make" something - topics I had avoided so far... I had no prior background in electronics and making stuff ; but I have a good experience in implementing signal processing software on mobile devices and desktop computers.
My goal was to build something small, inexpensive (~ 100€ in parts), with MIDI support, and -- in terms of synthesis -- a feature set similar to that of a classic bass synth, with some quirky stuff, and to stay as far as possible from the "8 bits"/"circuit bending" sound (mostly to make things harder). The synths I have played the most are an SH-101 and an ESQ-1.
The design I came up with is a bit unorthodox - the oscillators are generated and mixed by an AVR microcontroller (which also does the MIDI processing, user interface, etc.) using wavetables of band-limited waveforms (or FM, or a very crude formant synthesis), and the resulting audio signal (along with control signals for cutoff/resonance/VCA mixed from digitally generated envelopes, LFOs, step sequences) is fed to a CEM3379. There are no DACs, just the ATMega's hardware PWM.
The proto I'm playing with at the moment looks like this:
http://www.flickr.com/photos/mutableinstruments/4252632730/
Some sound samples:
http://pichenettes.net/shru/
I will post very soon the firmware code (gpl) and schematics (cc-by-nc-sa). When I will do so, I will appreciate advice regarding the PCB layout and the schematics. A couple of people around me have expressed interest so I have already ordered parts for 10 units to distribute a kit.
Stay tuned! |
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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| Posted: Fri Jan 08, 2010 8:06 pm Post subject:
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"Makes any other DIY synth out there look simple and stupid... "
Wow, tell us more!  |
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Dan Lavin
Joined: Nov 09, 2006
Posts: 649
Location: Spring Lake, Mi, USA
Audio files: 21
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| Posted: Fri Jan 08, 2010 8:18 pm Post subject:
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I agree with Ian. This looks like a good project. The sound samples are quite impressive.
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Synth DIY since 1977! |
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Fri Jan 08, 2010 8:30 pm Post subject:
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Thanks for your supportive comments!
Here are some specs:
I/O:
- mono audio output and input (input is sent to filter/VCA).
- MIDI in/out.
- 3 CV inputs (0-5V) on pin header.
- TX/RX/RST pins for onboard programming with an usb->serial chip.
Interface:
- 12 LEDs (current page / modulation matrix visualization).
- 2x16 LCD display.
- 5 switches to navigate through 12 parameter pages.
- 4 pots for patch editing (4 parameters per page).
- 2 inc/dec switches.
2 digital oscillators:
- Available for Osc1&Osc2:
* band limited wavetables: pulse, square (with pulse-width modulation), triangle with waveshapping, sawtooth.
- Available only for Osc1:
* sawtooth with sweepable resonance (casio cz-like).
* simplistic FM.
* lo-fi vowel synthesis (think “speak and spell”).
* cheap 8bit waveforms with plenty of aliasing.
* cheap square/PWM with even more aliasing.
* colored noise.
* 32 waveforms sweepable wavetable.
* “sweep” oscillator which scans through all the waveforms.
- Noise & sub-oscillator.
Modulation and filtering:
- CEM3379 filter.
- 2 LFO (square, sawtooth, triangle, sample & hold), syncable to tempo & MIDI clock.
- 2 ADSR envelopes.
- 16-steps step sequencer.
- 14 patchcords modulation matrix (16 modulation sources, 11 destinations). Modulation sources include MIDI controllers, pitch bend wheel and modulation, CV inputs, gater…
Performance:
- Arpeggiator with 15 different patterns + each of them with direction and octave setting.
- Support for (some) indian/arabic scales.
- “Patch performance” page in which 4 user-selectable parameters can be assigned to the 4 editing pots.
Others:
- MIDI implementation with patch load/save by SysEx, patch editing by NRP.
- Patch memory: 16 patches. |
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Drew83
Joined: Nov 03, 2006
Posts: 6
Location: Melbourne
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| Posted: Sat Jan 09, 2010 3:41 am Post subject:
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i've been keenly following this at Bhajis Garden and Palm Sounds - seeing those specs is exciting!
love the “Patch performance” page, great idea.
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Dego
Joined: Apr 22, 2008
Posts: 139
Location: Sweden
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| Posted: Sat Jan 09, 2010 4:21 am Post subject:
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cool  |
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RF
Joined: Mar 23, 2007
Posts: 1502
Location: Northern Minnesota, USA
Audio files: 28
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| Posted: Sat Jan 09, 2010 9:10 am Post subject:
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| Quote: | "Makes any other DIY synth out there look simple and stupid... "
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Dang. I've been wasting my time on my DIY synth. I could have waited for this and been satisfied.
bruce
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"I want to make these sounds that go wooo-wooo-ah-woo-woo.”
(Herb Deutsch to Bob Moog ~1963) |
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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| Posted: Sat Jan 09, 2010 9:44 am Post subject:
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| RF wrote: | | Quote: | "Makes any other DIY synth out there look simple and stupid... "
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Dang. I've been wasting my time on my DIY synth. I could have waited for this and been satisfied. |
Yep, sure all looks stupid now. Thirty years down the drain. Two oscillators!!! Can you imagine.
Ian |
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Sat Jan 09, 2010 9:55 am Post subject:
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| We all have to start with something , no matter how lame it may look to experienced makers... |
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24476
Location: The Netherlands, Enschede
Audio files: 298
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| Posted: Sat Jan 09, 2010 10:10 am Post subject:
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| jamboard wrote: | | We all have to start with something |
Sure, nice project too 
Its just that remark on your picture page .. ah well, at least you made someone happy 
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Jan
also .. could someone please turn down the thermostat a bit.
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v-un-v
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Joined: May 16, 2005
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Location: Birmingham, England, UK
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| Posted: Sat Jan 09, 2010 12:42 pm Post subject:
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I'm confused. Shruti-1?
UK based eh? I thought you were based in France??
 to the land of snow, ahem, Olivier Gillet, creator of Bhajis Loops??
http://github.com/pichenettes/shruti1
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Sat Jan 09, 2010 12:53 pm Post subject:
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| v-un-v wrote: |
UK based eh? I thought you were based in France??
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I'm half of the time in London (where I work), half of the time in Paris. Currently in Paris because my train was cancelled friday morning
Last edited by jamboard on Sat Jan 09, 2010 1:13 pm; edited 1 time in total |
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RF
Joined: Mar 23, 2007
Posts: 1502
Location: Northern Minnesota, USA
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| Posted: Sat Jan 09, 2010 1:01 pm Post subject:
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| jamboard wrote: | | We all have to start with something , no matter how lame it may look to experienced makers... |
It doesn't look lame at all, jamboard. It looks like a great project - congrats.
I'm just messing with you over that single comment
bruce
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"I want to make these sounds that go wooo-wooo-ah-woo-woo.”
(Herb Deutsch to Bob Moog ~1963) |
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simmeau
Joined: Nov 29, 2008
Posts: 32
Location: Brisbane
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| Posted: Sat Jan 09, 2010 1:26 pm Post subject:
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Yes, how dare you allow others to comment on your flickr
The sound samples are very nice. Keep us posted. |
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rubendelacosta
Joined: Dec 25, 2005
Posts: 153
Location: lisbon
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| Posted: Sun Jan 10, 2010 3:45 pm Post subject:
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very interesting project
are you coding on arduino?
i'm very curious to see the the code and the schematic. |
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Sun Jan 10, 2010 5:02 pm Post subject:
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| rubendelacosta wrote: | very interesting project
are you coding on arduino?
i'm very curious to see the the code and the schematic. |
I started with an arduino board (my original plan was to build a "synth shield" with MIDI in/outs, audio in/outs and the VCF/VCA) and then stopped using it. Software-wise, I didn't like the development tools and libraries -- I was tight on speed and code size and wanted to control everything. Also, there's a fairly large amount of python code which "compiles" lookup tables/waveforms, and I wanted to have this step integrated in the build process -- something easy to do with a plain makefile build. Hardware-wise, basing this project on an arduino would have meant a complicated design with 3 boards to stack or connect - the arduino, the synth board, and the front panel PCB, and a cost overhead ($25 for an arduino board while what I really need is a $5 ATMega328p and $1 for a regulator, a crystal, and a decoupling cap).
Someone has posted earlier a link to the code repository on github. Here it is again:
http://github.com/pichenettes/shruti1
The two PCBs currently look like this:
http://dl.dropbox.com/u/612135/PCBs/main_board.png
http://dl.dropbox.com/u/612135/PCBs/facade.png
(Which brings the question: where is it important to have ground planes? Is it better to have one big ground plane or have it in several "bits" connected by narrow bridges for each signal type [digital, analog, power supply])
Last edited by jamboard on Tue Jan 12, 2010 4:21 am; edited 1 time in total |
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v-un-v
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Joined: May 16, 2005
Posts: 8932
Location: Birmingham, England, UK
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| Posted: Mon Jan 11, 2010 3:35 am Post subject:
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Yes Olivier, that was me; jyotisweetcentre, terryfunken, or just 'Tom'
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ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN.
Last edited by v-un-v on Tue Mar 30, 2010 3:26 pm; edited 1 time in total |
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cloudscapes
Joined: Feb 09, 2004
Posts: 100
Location: Montreal
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Tue Jan 19, 2010 7:22 am Post subject:
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I should receive the 2 PCBs of what should be the final design within a few days. Meanwhile, I've played a lot with it to track bugs in the firmware - found only minor ones, so it's really getting rock-stable.
I have written a manual which presents all the features/synthesis parameters:
http://mutable-instruments.net/shruti1/manual
Those interested in trying to build it can fill this survey:
http://mutable-instruments.net/order_form
Thanks!
Olivier |
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2thick4uni
Joined: Feb 20, 2009
Posts: 113
Location: UK
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| Posted: Tue Jan 26, 2010 2:43 pm Post subject:
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| Demo's sound great! I'd definately buy a couple of pcb's if you decide to sell them separately. |
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v-un-v
Janitor
Joined: May 16, 2005
Posts: 8932
Location: Birmingham, England, UK
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| Posted: Tue Jan 26, 2010 3:21 pm Post subject:
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| 2thick4uni wrote: | | I'd definately buy a couple of pcb's if you decide to sell them separately. |
Yes, I don't know if you have sussed yet Olivier, but E-M.com has this obsession with PCB's and DIY. They (the PCB's) tend to come in two's (like Noah's Ark!)
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ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Tue Jan 26, 2010 4:03 pm Post subject:
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| v-un-v wrote: | | 2thick4uni wrote: | | I'd definately buy a couple of pcb's if you decide to sell them separately. |
Yes, I don't know if you have sussed yet Olivier, but E-M.com has this obsession with PCB's and DIY. They (the PCB's) tend to come in two's (like Noah's Ark!) |
Totally makes sense. And it's way easier for me to ship (fits in an envelope).
I will receive the new proto PCBs during the week. If there's no problem with them will order a small batch from PCBCart. For those interested, please register on the site so I can get a good estimate of quantities to order and notify everybody! |
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v-un-v
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| Posted: Tue Jan 26, 2010 4:06 pm Post subject:
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| Quote: | | Totally makes sense. And it's way easier for me to ship (fits in an envelope). |
Hooray! 
_________________
ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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jamboard
Joined: Nov 19, 2009
Posts: 18
Location: UK
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| Posted: Fri Feb 05, 2010 2:22 pm Post subject:
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Looks like FedEx has delivered the package with the latest iteration of the PCBs to a random guy. It totally sucks because more than 3 weeks have elapsed during which I could not move forward. Such a waste of time!
Anybody here could recommend a PCB house that can get something done within 4/5 days and which is not awfully expensive? |
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2thick4uni
Joined: Feb 20, 2009
Posts: 113
Location: UK
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| Posted: Sat Feb 06, 2010 10:36 am Post subject:
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| I've used Olimex to make one off PCB's, neither very cheap or very fast but very nice quality. They are in Bulgaria, however shipping to UK is usually less than 1 week - faster with Fedex etc but costs much more that way. |
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