Heck, no MIDI?
  • so i have to bild even more filters!
    well done!
    also available end of may?

  • Interesting to hear it in action. I’ve discovered it at github some time ago.

    I just ordered ten mcp6002 because I needed one, now I know what do with them.

  • I just saw this on the website, and I thought “When did this appear!!?? I didn’t see it mentioned on the forum??” Then I come back to the forum, and here it is :)

    It looks pretty damned good! I gotta give one of those a go..

    Great work Olivier!!

    Oh, and which filter does the sound cloud demo file use?

    Full kits or self source only?

  • @Rosch: I haven’t decided yet if I would do kits. There will be a few boards at the end of the month, yes.

    The samples were recorded with a, ahem, badly tuned SMR-4 filter board (there’s a lot of distortion/overdrive when the resonance is set to its full value).

  • boards? well, good enough for me!
    so seems like this time i’ll check the countdown very closely :)

  • hehe.. I couldn’t help but notice..

    The Sidekick has been proven to be particularly useful for the following applications:

    Grungy pulsating drones
    General Purpose Spaceships / Invocations
    Bells from Hell
    Software Failure! Press Left Mouse Button to Continue
    String machine / home organ Gentrification
    Self-osc Stomps
    4-LED Diwali decoration

  • very cool! will it play nicely with the extra capabilities of the dual SVF filter?

  • oooh:

    “If for any specific reason you don’t want to digitally switch between the modes, but rather want to build your own modeswitchamatron (one such reason would be that you want to use the programmer and like knobby and switchy things), remove the two 4053s and manually patch your favorite filter topology with wires between the pins of IC12 and IC13. The labels on IC12 and IC13 indicate which signals are available at those pins: “

  • i like it and i want it! will also the sidekick case aviabel pichenettes?

  • Is it designed to do anything beyond what you can already do with the Shruthi, when filtering external audio sources?

  • one question about the log pots: is it a big difference in range between the 50KA and 100KA?

  • Intriguing..


  • @oootini: it doesn’t play nice with the dual SVF which needs to read the switching data from the digital bus. But if you want to build a dualSVFotron, just leave the 4053 and 74hc595 empty and solder headers there to get a mini patch matrix :)

    @dalkiel: if there’s enough interest, there’ll be a batch of cases + boards, or even kits.

    @luap: it does audio rate modulations of the filter better than the Shruthi (on which CVs are sampled at 1kHz). Besides that, it’s only a matter of interface.

    @rosch: if you compensate by using 2x bigger caps (20uF) or don’t care about very slow LFO/envelopes, you can use 50kA.

  • Ah… Might be a good place to put my SMR-4 board. Which means might have to get an SSM or CEM board for Shruthi number 3…


  • thanks! i do care about very slow modulations, and i have a bunch of 18uF np electrolytics…. but i’ve just found some 100KA that match my 10KB (knurled shaft) and i have to order them either way

  • Whooopaaa! Great little piece of Hardware Fun and a MustHave™ for every Mutable Instruments Afficionado!

    I’d recommend a suboptimal tuned SMR-4 as an hommage to the original Seatle Grunge Sound. Anyone interested in my theory about Kurt Cobain?

  • Here’s a question, pichenettes:
    In the pictures there, you seem to have a knob with a light blue and a one with a dark blue pointer. Could you tell me where I can get the dark blue ones, and are the pointers orientated in the same was as the ones on the Shruthi-1 kit?

    Sorry for the odd question.


  • @toenburst. Wow, I don’t even remember. I have ordered some colored knobs in the past from Mouser (450-BA361) and from Farnell (1441138). I don’t know which is which or if it is just a variation in paint color in different batches!

  • I ask because I ordered a load of knobs from Mouser, and accidentally ordered two different varieties of the red and blue ones. One set of each had the pointers facing the wrong way. Annoyingly, the darker blue ones, which would have worked nicely with the dark blue case I got were the wrong way round. They look like the darker blue Release knob you have there, which means it must be possible to get knobs with dark blue pointers AND the correct orientation- hence my question. I’m afraid I obsess about these little details… ;)


  • Excellent! Here I was in this thread wondering what people would do with all their extra filter boards – BAM, now we have the answer!

  • wow, brilliant idea.

  • so i’ve made a first layout for my frontpanel, not entirely sure about some details.
    i assume the normal routing would be (from the pics on the website) VCA,VCF and Q connected (here banana jacks). i’m not sure what’s exactly cv1 and cv2.
    but looking at it i guess it would be better to have the regular connections normalled via switches and those banana jacks in addition (maybe some of them doubled?), but then i really need to make it bigger

    edit: i’ve deleted the pic again, the panel must be bigger.

  • hmm, eagle says CV1 and CV2 are there for the SSM2044 and SVF.

    the fact that there are two rows of headers for the voltage sources seems to suggest that it’s intended to also route one source to different destinations (at a time), but not routing different sources to one destination, as i get it. both would be easy with stackable plugs…

  • CV1 and CV2 go the SSM2044, SVF, and… digital filter board. The digital filter board will implement a digital SVF + effects, and I thought it might be cool to use the sidekick to control the effects with LFO and envelopes.

    We can route one source to many destination, not the opposite – the cutoff, resonance, etc. inputs of the filter boards are NOT summing points.

  • the sidekick is very inspiring!
    i can’t get closer to the border anymore and the knobs i’m going to use are big, so the easiest way to normalize the VCA, F and Q is adding a DPDT switch in the section of the panel, that closes the regular connection while cutting the connection to the jack. then there should be enough jacks actually. and if not, i can still stack them.
    am i right to assume that one could actually also fire the egs automatically from the mod matrix, by connecting a cv out to the pedal pads?
    (e.g. gate as mod. source)

    one more idea that comes to mind would be, in locked drone mode (mostly audio frequency) to send the lfo square/triggers through a divider and obtain a filter / vca modulation that’s in some way synced/related to the pitch (?)

  • > am i right to assume that one could actually also fire the egs automatically from the mod matrix, by connecting a cv out to the pedal pads?

    No, this is not correct. These are connectors for a passive pedal (a switch that will close the circuit). You should not put any voltage on those pads.

  • ah, i thought so, as the voltage that’s switched comes straight from the 5V rail.

  • btw i’ve found a switch that allows secure normalizing and patching at

    in case someone like to use it. it’s just one wire bridge to make on the switch.
    it makes sure there’s never 5V on any jack, the destination jack is always separated from the cv source, and you can always take cv and leave the cables plugged while switching. in theory.
    i’ll try to add 5 of these to my order (unfortunately ordered yesterday) and see if that works.
    i didn’t care too much about the 0V, i find 5V more interesting…

  • i’ve had success in college snipping out the tiny pin holders from a chip socket (the circular type ones) soldering them in place, and then using breadboard jumper wires as pretty sturdy mini patch cables. in this case you could use a very thin drill bit (the one you’d use to drill holes in a diy etched pcb) on the faceplate and glue the mini sockets in place.

    instant mini patchbay!

  • cool, they work fine. i’ve had not so much luck with the higher profile type (the ones that connect the Shruthi boards, they’re wider)

    another thing:
    as the cv’s are all buffered, it should be possible to control 2 filter boards with the Sidekick, given that they’re all on the same power supply of course. i’m still thinking of the 3 filter orchestra fcd72 is going to house inside his controller…

    and yet another thing:
    the sidekick also seems to be the ultimate solution (aside from the 4x16 Exfilinator) for providing external 0-5V cv modulation for the Shruthi herself (without fcd controller)...
    (and without the drone lock function)

  • yikes!
    i disappear for a while and when i come back…
    i’d love to get hold of one of these, i have a spare filter board that needs a home :)
    ‘hope i can grab one of these boards ;)

  • pichenettes,
    is there a technical reason for not implementing the same means of control for the resonance cv (not necessarily speaking of drone3), or is it rather a matter of concept (as it’s not so important, obviously, or comnpatibility in boards size) ?
    it’s no criticism at all, but it would be interesting to know :)

  • the true reason is that the laser can only cut 12 holes in the same size…..

  • :D
    so still a technical reason, in some way!
    musikding will count me as nuts when i’m going to increase my order yet again…

  • let me guess: big fat bakelite knobs?

  • You mean not having a dedicated envelope / LFO for resonance?

    I was trying to find the most useful I could with 12 knobs, and this is what I came up with. I figured out resonance did not deserve it – after all there are so many filters in which resonance is not even CV-controllable…

  • @pichenettes
    yes i can see the point, i use cutoff changes much more than resonance.

    you got it. the big mxr knobs usually cause 2-3 weeks waiting time, as there is not enough demand to have them ready, apparently. so i actually could still add things…
    i think i just keep it stock this time and do the nuts thing on a weirdo orange panel :)

  • pichenettes said: “CV1 and CV2 go the SSM2044, SVF, and … digital filter board.” And? Not or or and/or? Not SMR-4/CEM3379/IR3109?? Why not? I feel like I should know why not but I don’t. Sorry.

    While I’m at it, not knowing and all, whats an egs? An envelope gate signal?


  • @ KSD

    Because on the other filters theres no need for additional CVs ;-)

    OK, look at the Digital Board, theres an F (cCutoff) and Q (resonance) Output from the ATMega, basically its the same Output as CV1out and CV2out, but with a fixed purpose, hence its not called “Controll Voltage”. As the SVF Filter Board contains 2 Filters you need additional CVs to control the 2nd Filter, so CV1 and CV2 are used.

  • it corresponds to the menu, on the SMR4 and CEM you also have just one filter page, while the SSM2044 has a high pass function added (by pressing the filter button twice)

  • I see… browser tabs full of filter pages.

    Ha. Thanks guys, I get it now. Right now that is. I think I’ll be alright as long as I don’t think too much about the sidekick. :)

  • is there any (simple) way to trigger the two ar envelopes externally with lfos or gate signals from analog sequencers?
  • @mic.w: no this is not possible.

  • so i guess you would need to add some kind of v-trig to s-trig conversion? like you do for triggering moog synths or the tap-buttons of digital delay pedals etc?
  • I hadn’t head about s-trig before, but yes, this is exactly what is expected here.

  • cool, that shouldn’t be too hard to do.

    for anyone curious but too lazy to google: an explanation of v-trigger vs s-trigger can be found in wikipedia, schematics for the conversion circuit can be found here or here.

    @pichenettes: how about including two v-trig inputs for the envelopes in future sidekick board revisions?

    [edit:] oh and, incidentally, i’d be interested in a kit! :)

  • @ootini. your mini-patchbay is a great "little" idea.
  • can we have a sidekick demo showcasing it filtering a shruthi instead of self osc stuff please?

    id especially be interested in a digital filter shruthi through a sm4 equipped sidekick, as that will be the combo il be running first, when I can get my head around ordering all the extra bits, but anything will do.

    thanks :)

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