• Hi, I’ve just finished my Anushri, and I was planning to add some mods to it. I have a nice hammond enclosure around here that’s a little bigger than the stock case, so I have space to add some new controls and things.
    I’m thinking on adding a second vco, a second filter in parallel with the standard one, and some new modulation sources, like a new adsr and lfo. I’m using a modular Eurorack to test the possible mods. I have some wires connected to patch points in the pcb and now I’m trying different things.
    The vco is working nicely and adds a lot of meat to the sound. The combination of two vco’s+suboscillator is killer! The signal from the new vco goes into pin 13 of ic10. I’m going to place an attenuator there to have a level control for the new vco. Then I take the mix out from pin 14 of the same ic10 [tl074] and route to my new filter [it would be a 4pole, but I still don’t know which one]. I can hear the signal from the new filter in my modular, but now my problem is that I can’t find a way to bring it back to the Anushri!
    The idea is to have a pre filter mixer where you mix the sounds from vco1, vco2, and the selected signal assigned to the sub pot [sub-1, sub-2 or dco]. Then, this signal goes into the two filters and to a final mixer where you can mix the two filters signal. So I need a point where I can add the sound from my new filter to the original Anushri filter. I’ve tried the vca in, as appears in the schematic but with no luck. If I put there the signal from the new filter the sound from the Anushri output disappears; if I use a resistor, simply nothing happens. The same thing occurs if I try to use the point marked vcf out in the schematic.
    I don’t know electronics theory, and here is where my knowledge is not enough. I would be very happy if somebody has any ideas about this.

  • Put it at the VCA input.

    AC coupling cap (4.7u or higher) >> resistor (22k to 100k) >> IC4 pin 14.

  • So is your vco coming from a modular synth unit or some other custom device?

  • Thanks a lot pichenettes, it worked!
    Right now, the vco I’m using [and the filters, and everything else] come from my modular Eurorack. To patch it, I use Anushri’s jacks and some wires soldered to pcb points. Now I’m just trying to see if this works, the connections and routing, etc. After that, I’m going to put all together in the case with the Anushri. I have some pcb’s, some semi-finished modules, and a fully built Mfos VCO. The idea is to find a nice sounding setup and put it all together. I’m going to try a semi-modular approach: the audio path will be prewired, but you’ll have patch points for modulation.The case I have is not much bigger than the stock case, I don’t have a lot of space, so I’m no making a monster. But it will be nice, I hope :]

  • this sounds cool. good luck!

  • @Silesius
    WARNING! Shameless self promotion ahead:
    Have you seen this?

  • fcd72, yes I’ve seen that, and they’re nice, but that’s not what I’m looking for. The idea is to build one custom front panel for the Anushri with all the extras. I have one of these boxes that’s more or less 25cm x 15 cm. That gives me a little extra space to add some knobs, switches, etc…

    600 x 600 - 36K
  • @Silesius
    I can well expand it to the right to add all of your desired jacks…..

  • @Silesius
    I should like to know where you acquired those cases. I have a worst case scenario.
    cheers and regards

  • That’s right, they are from Hammond. I bought mine at Mouser.
    They come with a bottom cover; they don’t have front panel, you have to drill the case itself. So I’m afraid I won’t be able to use fcd72’s services.
    Back to topic, I read somewhere in the forum that you can trigger analog drums with Anushri’s drum “sequencer”. If that’s true, it would be great. So, is there a way to get three separate gate/trigger signals to interface with analog drum modules?

  • The Anushri spits out the MIDI Notes for the Drums, so no analog Trigger. Grab a PicAxe 28x2 and some OpAmps for buffering and ill pass you the code to parse these notes and produce a Trigger Signal ;-)

  • > So, is there a way to get three separate gate/trigger signals to interface with analog drum modules?

    Not without a code modification and a little expansion board…

  • @pichenettes
    many thanks

  • Thank a lot fcd72, but I’ve never used a thing like that [I’ve learned what I know, which is not much, by building analog synths] ; it would be nice, too. If I had to try that, what should I need? The Picaxe itself is not expensive, but I’m afraid that’s not all I need. Will I have to buy some “starter kit” or something like that? If I buy that, you just have to give me a code to program the chip, is that right? And, once the chip is programmed, I just have to connect it to the board and I will have my three gate signals? Sorry for the dumb questions, but i’ve never used something like that, so I’m not really sure if I am going to be able to handle it.
    On the other hand, I’m really excited with the possibility! I’ve been a lot into analog drum circuits lately, so it won’t be hard for me to build three small drum modules and add it to the Anushri[I will have to buy a bigger case, though].

  • @Silesius

    You need a Chip (get 2), a download Cable and the free Programming Editor and the will to learn. You’ll need a 6N137 for the MIDI In, a TL074 or a 74C15 or something else to buffer 4 Outs and the will to learn how it works. Then you can build an universal Note-> 5V Trigger thingie.
    The hard thing is not the Sound generating Circuit its getting the Anushri to output 3 GATE signals for the drums as its not designed to do so. If you won’t modify the Anushri you’ll have tu build an external solution; Anushri spits out the MIDI Notes so why not use these?

  • @silesius:

    is think fcd72 is right about how simple and easy the picaxe stuff is. i got started with it really quick for simple stuff like that.
    if you build such a thing: why not use a normal case for the anushri and put the “picaxe midi->trigger thing” in another case together with the analog drums.
    this way you can also use the drum maschine with another sequencer.

    i am interested in your drum circuitry by the way. (i ordered the parts for the eric archer 808 kick clone and am interested in mybe doing something similar with it)

    please keep us posted about your progress.

  • How many of you need such a beast. ITs actually wuite easy to make an special AnushriDrumGateOut Thingie but I’m have no interest to do a one off…

  • sure, count me in

  • Individual drum triggers would be great, but I’d like to avoid Midi. Any ideas on how to do that?

  • Then you’ll have to tweak Anushris Firmware – and find some spare Pins. Taking a quick glance at the schematics i don’t spot some…..

  • Hook up a 74hc595 to the shift register expansion port on the board. Add a ShiftOut with the register bit mask somewhere in the code.

  • Whats the refresh rate for this? In the end its worse than MIDI ;-)

  • 4.9kHz, so 2.5x the rate of what you can get with MIDI note messages.

  • OK then, flip, you know what to do ;-)

  • Yess, thanks :)

  • btw, I had to change 2 lines in .gitmodules to checkout the submodules:

    url = git@github.com:pichenettes/avril.git
    url = git@github.com:pichenettes/avril-firmware_tools.git


    url = git://github.com/pichenettes/avril.git
    url = git://github.com/pichenettes/avril-firmware_tools.git
  • Regarding timing, 4,9kHz per Bit, Per Byte, of for the 2 Bytes which would be needed for the TriggerOut?

  • Per shift register refresh. One refresh is 1 byte / 8 bits, enough to generate 8 triggers out (one could have 3 triggers + 3 accents + 2 random gates or extra digital LFO).

    Yes, Anushri refreshes much faster than the Shruthi – I wanted it to have a higher spec’ed control/clocking/timing section – the only CPU intensive thing it’s doing beyond refreshing is the drum synth. No oscillators!

  • cool brand name, fcd

  • so for the 2nd byte its still 2,25 kHz which is twice as fast as MIDI... cool

  • No, the refresh rate is 4.9kHz. Everything that has to be written to the shift register is written during a refresh. Writing a byte in itself takes 2µs, so there’s not much difference between writing one byte (current code) and writing an extra byte (modified code) :D

  • facebook?

  • nearly. me not fbook ;)

  • Wow! So maybe this is going to happen? That would be great. Right now, the Picaxe thing is too much for me. Besides, I’ve noticed I’ve got a diy midi to gate interface in my modular, so actually I can trigger drum modules with the Anushri. But if there’s a way the Anushri itself could do that, maybe I wait and build a self-contained analog supergroovebox :D

  • Separate trigger outs for the drum machine would be really great, or maybe even an “Anushri eurorack extension panel” like are available in the eurorack-world (dixie ctrl, pittsburgh gen-expander, 4ms rcd scm breakout panels…) regrouping all modular-related Anushri mods like separate waveform out for the osc, some extra cv in-outs along the signal path, front panel access to midi ports…

  • anybody planing to do the trigger out mod oliviere suggested?
    i think its no problem to do the 74hc595 expansion on a piece of pearfboard. with 4050 buffer just like the gate and clock out on the mainboard.
    but i have no idea about how to mod the firmware.

    accent outs would be great, too. i am thinking about pimping up the snushri bassdrum (with this for example)

    what is your panel for, fcd72? picaxe midi->gate or the 74hc595 expansion?

  • @loderbast
    depends on flip who its the demigod of firmware modding ….. is he hasn’t time why not grab a 20x2 and a 137N?

  • thats true. i have both at hand, but i think now i want accent out, too.
    i’ll have to wait for those freaking switches anyways before i can start anushriing.

    lets hope, flip or someone else is up to it.
    i am planing on refreshing my c/c++ skills, too. but that might take a while.

  • Has anyone done this mod?

  • .
    Nope. I build myself à little midi to trigger module just like fcd72.
    I still plan to do it though.

  • @loderbast
    This is your territory from now on ;-)

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