The Shruthi-1 Programmer - FINAL EDITION SOLD OUT!
  • I’m asking myself the same question, and i think cause the cv1 input is straight from this output expansion…Anyway i just own a 0.5 rev :D ….

  • > Why not put a CV1 on the new “output expansion” part of the board? Just wondering.

    Because this is an input, not an output :)

    The “output expansion” is not just for the programmer. Most of the other uses I have in mind for it (controlling analog switches on a filter board, controlling a digital filter board, displaying fancy LED animations…) do not require an input.

    And duplicating I/O ports on a board can make things pretty confusing…

  • @CheeseNoOnions…asfar as I understood, you won’t be able to use 1 programmer to tweak two separate shruthis at different moments….I mean, if you plug your programmer to shruthi #1 and shruthi #2 and want to only tweak shruthi #1, this won’t be possible as shruthi #2 will wait for CV infos when scanning the programmer pots (at this moment not plugged to shruthi #2) you’ll get randomized values for your 32 synths parameters on shruthi#2 when tweaking shruthi #1….This is why I was thinking of a way to virtually feed the unplugged-to-programmer-shruthi…

  • Yo CheesoNoOnions,

    very cool job! Do you have 0.92 Firmware already? If not, drop me a line.

    Unfortunately – as Tom pointed out – its not possible to just switch a programmer to different Shruthis. The Programmer is just a bunch of dumb Logic Gates and all Shruthi does is send Data to the Gates which switch the apropriate Pots Voltage to CV1in. Thats all, there is no bidirectional communication between the Programmer and Shruhti so it won’t notice if theres a programmer or not. This information you will have to tell Shruthi via the System Settings Page and it relies totally on your order.

    One possible solution would be to switch all lines and ground the unused CV1ins. This way the Shruthis that were not selected would have a defined Value so the read values would not randomly change after the inital setting of all Parameters to 0 when switching. All other possible solutions are way more complicated and costly then just building some more Programmers…...

  • Awesome work cheese no onions (Cheese and onion FTW tho!)

    Bob Ross – lol.

    Almost inspired to build one from the schems myself. Almost!

    But not. :) Waiting for the kit for me. Although i did order some 4051s i now have no idea what to do with. Doh!

    Great job.

  • @ fcd72
    Hey, I am planning on building the programmer in the next few days, but am having trouble building v0.92, could you possibly send that to me built as a midi file (I have had better luck with midi)?
    And in the pictures, you say there are some bugs still in the programmer, should I wait for a more complete version, or go ahead and perfboard it with the schematics you gave?

    my email is lifeisaforeigncountry at
  • @n8bit:
    He said the schematic was current.

    I would have LOVED to get the kit with all the goodies, the shirt especially, but I unexpectedly left my lab for an opportunity to return to graduate study and once again bask in the pleasures of sleep deprivation and poor diet. Maybe we can donate via paypal to fcd72 for the schems. Or a barter, like…. if fcd72 ever has a paternity issue I can run the DNA discreetly. Or perhaps…......flub the results?

    A friend wanted a DroneLab (casperelectronics) but has no electronics equipment or experience. I offered to
    build it for him if he also bought me the extra pots, knobs and 2 ICs I needed to attempt the programmer. This is also why I’m recycling enclosures. lol You know that bob ross thing was great to work on! I usually buy my enclosures from Fry’s or some electronics place, and spend weeks carving and drilling and generally destroying it.

    The BobRoss comes with a great decal, is really hard plastic and the base (what the perf board is screwed to) is a really solid metal. Would’ve worked for the drone lab too I’m guessing.

  • @n8bit
    The schematics are correct and the PCB-Layout for the Programmer works perfect. There are just some very dense Spots between the Legs of the 4051s i need to correct for easier buildability – i dont want everybody messing with these superdense lines and shorting everything.

    For such brave guys that quit their jobs to study again i always have a shirt…. and a useless diode ;-) The final layout of the PCB will be available for download and if you (or someone else) want to etch the beta version yourself drop me a line.

  • @fcd72
    If you put all the pot lines to ground, won’t the shruthi read 0V for all pots, and as a consequence put all synthesis parameters to 0 ?



  • @Tom

    Xactly. You can then change the parameters to whatever you like via changing the Patch or CC, as long as Shruthi reads the same Value from the Pots it assumes you did not touch the knob hence doesn’t change the Values. If you leave CV1In unconnected it will read random Noise from the open gate, think you turned the Pot and change the Value of the Parameter.

  • Guys,

    as i said before, im thinking about dropping the Blacky Case

    as its a bit to costly (takes 6 times as much Plexi as the Standard Enclosure).

    Heres a very (very!!!!!) rough draft of the new version, it will be about the Size of a sheet of paper (landscape ;-) ) and capable of fitting Wooden Side Panels for those grabbly high end haptic afficionados.

    Let me know what you think of it.

    P.S.: I will sell the Blacky-Prototype including the Shruthi, as soon as i have a new SMR-4 Board for it – it has square LEDs and Round Buttons and is strictly limited to 1 (one) item….. stay tuned!

  • Awesome work frank, looks amazing :)

  • oooh, this is starting to look very tempting indeed…

  • very clear layout, I like it! :-)

  • As much as I like the idea of an integrated control surface with the shruthi on board, I’d still would go for a PG-200 style knob box..

  • @altitude

    you may well cut the lower left corner with a saw… ;-)
    Stay tuned – and imagine the Envelopes and LFOs in one row left to the OSCs

  • im thinking (in the fullness of time… :D);

    One like the above, with built in shruthi made of something solid for live stuff.

    And a smaller Pg type deal for my cramped studio, with a long cable.

    is the one above just a drop in shruthi (with sides, back etc) or just a top panel ?

    I assume the programmers are ‘dumb’ – if i had two, i could swap them about easily enough.

    I cant wait for this to be ready. Ordered a new memeroy chip for extra patches too.


  • Looks great. I usually prefer rack mount gear, but this has a really nice old-school vibe.
  • Nice work fcd !! But may I ask you some questions ?

    can you tell me :

    - what the control output voltage 1 / 2 situated at the top are intended for ? – why are there 4 knobs CV1 to CV 4 on the right side ? – how can we gradually switch from 2 poles to 4 poles filter ? Is that already possible ?

    and most important: with this design, the shruthi case being in the bottom left corner, how do you plan to access to MIDI and audio connections ? Do that mean we’ll need to desolder some parts ?

    Once again, nice layout (effectively much more better than mine !!!)



  • @tom

    • the cvOut on the top are just 2 LEDs as indicators for CV1 and CV2, there will be jacks on the backside (3,5mm i guess..)
    • the knobs are planned to deliver CV 1-4 from the pots used as voltage divider. Note that this is exclusive to the programmer use… ist only a “maybe” feature.
    • unfortunately and most of all luckily this is no emulator so we do not gradualy morph between 2 and 4 pole mode. its just a switch on the frontpanel instead of a jumper on the SMR-4 Board
    • the filter boards (plural is a hint! ) are positioned at the back of that enclosure, there will be the option for an internal power supply for all of you that xactly know what they are doing. you dont have to desolder anything, there will be new midi connectors on the backside and you can easily solder the 2 wires per connector directly to the board. oh, and there will be a power switch as well….

    I just came back from my local woodworking wizard to check if he can do the sidepanels for us. yes, he can!

  • Waaaaoooowwwwwww !!! Good work ! With so many difference between the beta programmer and the almost done programmer, do you still stay in the price fork you gave at the beginning ?

    And for the front plate, will it be made of wood or will this be a metal plate ?



  • The Programmer Kit itself will be the same, the Enclosure will not be cheaper than the Blacky one. But it will have wooden Sidepanels ;-).

    The Enclosure is made of Plexi, Color to your favour and you shurely will be able to choose from a variety of different Wood for the Side Panels. Or live without them. The enclosures are entirely custom build so if you want a different Font or drop the 2/4 Pole switch – no problem.

  • feck! Between this and the new firmware the shruthi is turning into a complete beast !

    Im going to have to build another to go in that one. Kind of attached to my first working diy project.

    Put me down for a preorder for that as well as the kit.

    I can pay preorders from the 10th if any help?

    I assume theres room in there for the 2/4/4051 filter thing.

    Well good.

    Might even go mad and do an IR3109 version.

    Thats soooo cool.

  • Hi there,
    I would like to get on the list for the enclosure. I do not need the wood side panels, unless that's the way they will come. Also interested in the programmer kit, depending on the price. I can put down some cash for the pre oredrs as well if that helps.
  • I'd also like to get on the list for a kit. Happy to preorder. This looks *incredible*. I'll whisper my e-mail.
  • Hi,

    Any news on a group buy for the remote/case kit or is there not so much interest anymore ?
  • You can definitely put me down for one of these. It's looking great. I'm in
  • @prophonic

    currently i am very tight on my time (as always in the first Q of the year) so it takes some time revising the pcb. The schematics are ok, but there are some dense spots that make building a bit difficult. If the v0.2 Board is ready ill do the new enclosure. If everything is finished you will see a lot of pics here and ill contact the ones that are on my preorder list. I wont make any prediction when this will be expect asap ;-)

    As far as i can see there will be 25 complete kits on the first run, and as many Enclosures as necessary.
    Complete Kits will include everything to build a programmer expect knobs + enclosure (and a T-Shirt) and Enclosures are always custom build to your favor.

    As from everyone that wants to get on the Preorder List i need your eMail, RealName + T-Shirt SIze, please drop me a Mail

  • where can I find your correct emailadress?
    want to get on your preorderlist :-)
  • click on his name then you are in his profile

  • Id buy one programmer kit eventually. First i need one Shruthi, then second and maybe even third before that. :)
  • @fcd72

    anyhow, your emailadress does not work for me?
    can you put me on your list, too?

    youkon-wellenreiter ät

    best wishes, julian
  • btw, What are the final dimensions for the PCB and what sort of I/O is involved (i.e. is this shurthi powered or does in need its own supply). I have some time now to work on this..

  • Final dimensions will be 1/2 Euro Format (80mm x100mm), right now im redesigning the PCB to use other Connectors and a few other things. The Programmer is 100% powered by Shruthi.

  • I am starting to really think about this now, so some more questions:

    So 6 pins will go to the synth?

    For the LFO sync, are those pots or just on/off switches?

    On your concept on the last page, if there anything there that is wired directly and not part of the mux?

  • 5 Wires connect the PCB and the Output Expansion Port on Rev 0.6 + Boards. On Rev 0.5 Board you can as well solder them directly to the Digital PCB.

    In the kit its all Pots as the LFO sync (in 0.92 “mod”) has (for now) 3 values: free, slave and master. You could use a switch with some resistors, but note that in future revisions of the Firmware there could be different amounts of values.

  • oh i thought there are 6 wires

  • yeah, I count 6 as well, did you forget gnd?

  • No, i did forget CV1 ;-) You are right there are 6 Wires: 2 for Power Supply, 3 for the Shift Register and CV1 back to the Shruthi.

  • Hi there,
    so I built a programmer based on your schematics.
    When enabled the synth starts generating random noises. The pots do seem to work, the numbers on the shruthi change according to what pot I'm altering in a correct fashion, though do jump around alot. When I change patch, the same random sample and holdy sound is generated. Something is not right. Sure I'm being stupid and missing something basic.
    The CV 1 wire goes to the hole IN1 on the input expansion part of the shruthi, right?
    Any ideas greatly appreciated!
  • Yo kogz,

    brave guy, id like to see some pics;-) CV1 to IN1 is right. SampleHoldy sounds indicate that theres no measurable voltage on the analog in. Try to identify which parameters are floating by switchin with the buttons and having a look, 4051 #1 is for parameter 1-8 from the list etc…. Then check with Mr.Voltcraft each midle pin from the Pots if theres a voltage, if yes you may have bridged some pins of the according 4051.

  • yeah looks great!

  • really nice !!!!!
  • Cheers!
    Fiddling around with getting that picture uploaded…Unfortunately each envelope now has 2 controls for Decay (DOH!), so I’m gonna have to re silk screen it. I think I’m gonna move a couple of parameters an re label a few as well, so it wont be 2 much of a hassle.
    So I measured the voltage and am getting steady voltages from the centre pin of all the pots. I have common ground wired on all outer lugs on one side, common 5v on the other. Is this correct?
    It seems like all parameters are jumping around, judging both from the screen and the sound. The board I made was based on my own eagle brd from your schematics, so maybe I made an error somewhere there. I think I’m gonna knock up a new brd based on your layout.

  • Cool, I think I made the 303’rd comment…

  • WOW!!!! really nice. I want one ;-)

    Move every Pot to +5v or GND and try probing the CV1 line with a scope. It should show a steady signal. Else you made some mistake with wiring the 4051. Maybe the adress decoding is bad, try an connecting LEDs on pin 15-13 of the 74137. It should blink nicely indicating the selection of the 4 4051s. And connect some LEDs to Pin 15 + 1 + 2 of the 595, indicating the three bit adress bus for the 4051s. If everything blinks nicely the adressing of the 4051 analog switches seems to be ok, then it must be a problem with the analog part your board….

    Can you post a Pic of the PCB-Layout that i can check?

    Oh, and your comment was #322, obviously theres a lot of whispering going on here…

  • Darn!
    Thanks for the tips. Tried the scope on CV1 and got a flat line. The leds are blinking in the places you suggested. The analog section works fine when the shruthi controls it, but as soon as I change the cv to prgm all kind of randomness ensues. I will make your brd soon to eliminate any schematic mistakes I made.

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