I can't manually tune my Anushri
  • Finished my Anushri a few weeks ago, I’m loving it but I really want to CV it with my microbrute. Unfortunately I can’t seem to tune it. I’ve adjusted the VCO V/oct trimmer as low as it will go and when I play an octave I’m seeing larger than an octave in my tuner. It works great using the automatic tuning, I just can’t seem to get the CV tuning to work.

    I did make a mistake in my build, I broke a pin off the ATMega chip (VCO Square Out, #15 under MCU here http://mutable-instruments.net/anushri/build), but after screaming for a bit I managed to solder a pin to the chip while it was seated. Everything seems to work okay otherwise so I think the connection is good, but maybe I’m wrong.

    I saw another poster with the same issue saying to replace R61 by a 91k resistor ; and R75 by a 20k trimmer. I guess this is what I need to do next? Just wanted to make sure before I started desoldering things

  • This will solve your problem but I’ll have to investigate. This did not occur with the first 2 batches of kits…

  • I’m having a similar problem with tuning mine (not the atmega pin thing, I just can’t get it tuned. Mine also works fine with automatic tuning.) I ordered around august, I think. Is this a known issue with recent kits, and is the R61 and R75 replacement a proper fix?

  • That’s a fix in the sense that it extends the range of the tuning trimmer.

  • Cool. I’ll try that.

    ...and actually, come to think of it, I sourced my parts myself – didn’t buy a kit. Since I’m sure it’s not a problem with the PCBs, I’m sure it’s some parts screwup on my end.

  • Just to let you know, I never got mine to track more than 2 1/2 octaves. It was good enough over a few more but now that I’ve started pairing it with my modular, the error is a problem. That’s with the replacement R61 and R75.

  • I’d like to add a me too here. Everything else is working great on the Anushri (I finished it yesterday), but with the v/Oct trim fully clockwise, I can’t get better than a bit over an octave spread between two notes an octave apart. Looks like I should go get a 91K resistor and a 20k trimmer.

  • I just like to state here that i have the same problem. I get about 4 octaves with around 98 % match and then it is defintely too far off for exact tracking. I have the modular faceplate and a kit from beginng of the year. And i have the weirdness that my volume poting is working very late, in means in the first 60% of the rotation it does nothing. I ask myself if this is regarding tolerances, as i found no errors in the placement of resistors so far.

  • Same here. Mine is from last december, when the front panel came out. As piscione didn’t get to work with other modular stuff ‘til a couple of weeks so didn’t made a proper tuning.

  • > I get about 4 octaves with around 98 % match and then it is defintely too far off for exact tracking.

    That’s normal.

    > the weirdness that my volume poting is working very late

    That’s not, probably a damaged pot?

  • I feared to hear this, i’ll check it – if necessary. I have more than enough headroom in my interface, so i may live with that…

  • A quick update… I swapped to a 91k resistor and a 20k trimmer, and all is working as expected. Octaves are now acting like octaves. Hurray!

  • I swapped the resistor and trimmer and now I have a new issue… The synth is incredibly quiet running off CV. So quiet you can barely hear it over the drums. I might need to do some experiments to figure out what exactly the issue is, but it sounded before like the filter cutoff wasn’t opening all the way. Which is odd, since running off MIDI it all seems fine.

    Any idea what I could’ve done? Maybe I broke the pin I soldered on the ATMega chip?

  • Hmmm not sure I understand…

    When you trigger a note with the CV/Gate inputs it’s quiet, but with MIDI it’s loud?

  • Not sure what I did but it seems to be working now.

  • Chiming in here… I have the same problem, I get a bit less than 13 semitones for an octave where I should be getting 12. Will try to get a 91k resistor (why do these come in such weird denominations?) and a 20k trimpot tomorrow, swap ‘em and post the results here.

  • I did the modifications (resistor and trimpot), which helped but did not make everything “all better.” It’s great over two octaves but drifts after that. I have my Anushri mounted in a small tool briefcase, paired with some Euro modules. The reason I wanted to get the tuning to work better was because I wanted to pair it with another Euro VCO. It’s not too bad, but not as good as the other VCO so the pair start to sound kinda odd after a couple of octaves.

    What I may do instead is pair the Anushri with some Euro effects instead of adding another VCO. I could add a delay, filter, waveshaper, whatever, and still have a cool standalone box without the added VCO. Then I could use the software tuning in the Anushri.

    Just out of curiosity, does anyone know of a small Euro module that will generate a second wave when fed a signal from a main VCO?

  • Just wanted to report success. I could only find trimpots locally with their pins set in a triangle instead of a straight line as required by the Anushri PCB, so I started by only replacing R61 by a 91k resistor. That already fixed the problem. I have 5 octaves almost perfectly tuned, with the weird exception of C1 which is 15ct off so I settled on a compromise tuning which makes everything 5ct off and C1 10ct. Tuning the VCF also went great, with 5 octaves within 10ct.

    One weirdness: On my Anushri, switching sync on and tuning the VCO below the DCO does not silence the oscillators, they’re still very well audible. But in this configuration, turning PW all the way to the right does. Is that expected behavior?!

    Anyway, thanks a lot for the advice everyone! This forum is awesome.

  • Hah, just found this thread after scratching my head and assuming I’d got some resistors switched or something. Glad to know I’m not the only one having this exact problem. A minor 9th is the smallest interval I can get…

    @pichenettes: Did you figure out what happened? I mean I now know the fix, but I’m curious if you know why this has occurred with so many kits? All the resistors I had in the kit matched the values printed on the board (and included in the build guide)... unless you got a batch of mechanically dodgy trimmers (perhaps they’re getting stuck before the proper end of their travel)? I don’t know enough about electronics to guess any more than this. I sympathise with the nightmares the kit business must have caused you…

    @bjoern: You are turning the mix to 100% square, right? As I tune my VCO below the DCO its pulse width decreases and it eventually falls silent. I think the theory is that the square is getting reset earlier and earlier in its cycle, eventually it’s getting reset before it flips and thus falls silent.

  • > Did you figure out what happened?

    Not at all!

  • Oh well, hopefully I’m the last person and it’s behind you now! Thanks again for your help over email.

  • Running into the same issue, I’ll report back when I get a the 20k trimmer and resistor.

  • swapping resistor was enough in my case

  • Just got mine in a euro case and tuned it up and had the same thing – put in a 91k resistor and everything is hunky dory.

  • Nice work, I must’ve really screwed something up. Never got mine to work. I can get maybe 2 octaves out of it.

  • I managed to get C1 and C4 within a couple of cents after doing the fix, so I’m happy*.

    *I have just discovered another problem, not sure if it was there all along or if I buggered something up while doing the fix. Needs another thread though.

    @Endorfinity: That makes sense, looking at the schematics, the 10k trimmer is simply configured as a variable resistor in conjunction with the 100k resistor. So the trimmer is giving you from 110k to 100k normally. A 91k resistor lets us vary from 101k to 91k, where the proposed fix of also changing the trimmer to 20k gives us a new range of 111k to 91k. Both work, but changing the trimmer also makes it fiddlier to tune… I shoulda just changed the resistor.

  • I’m also having troubles tuning my anushri.
    I’m sending C0-5 cv using my beatstep pro. All i get is approx. 10 semitones instead of an octave. Trimming the V/Oct or the Offset BOTH change the offset.
    I checked the trimpots, power supply, reset the unit, and made the R61 change (all i had was a 82k instead of 91k).
    The tracking works fine in MIDI using the auto tune.

    Help !

  • Don’t worry about the offset to begin with, just try and get the interval right with the V/oct trimmer and only then worry about making sure your Cs are actually Cs.

    82k might be too small and could explain why you can’t get the interval big enough. When mine had the originally specified 100k resistor, I was struggling to get the interval small enough – I reached the end of the trimmer and still had more than an octave. By putting in an 82k instead of a 91k, I fear you may have overshot. Have you got a 10k resistor you could put in series?

  • From the original message:

    to replace R61 by a 91k resistor ; and R75 by a 20k trimmer

    Just changing R61 makes things worse. You also need to change R75 for the fix to work.

  • @pichenettes: But aren’t R61 and R75 in series with their total resistance deciding the scaling? The original selection was 100k+10k, giving a range of 100k to 110k. Your solution expands the range (to 91k to 111k), but wouldn’t changing the fixed resistor for a slightly smaller one do the job? Instead of increasing the range, it would shift it.

    Of course, by putting an 82k they have shifted the range so that the most they can get is 92k… and less than an octave in the scaling. Surely as long as they got R61 ‘right’ then they could leave the trimmer at 10k.

    Of course, maybe there are factors at play that I have no idea about.

  • > wouldn’t changing the fixed resistor for a slightly smaller one do the job?

    Yes, but this is not what dalhasumai has done. If you change R61 for a value which is too low, you have to increase R75 to compensate.

  • Ah ok yeah. I thought you were saying that ‘in general’ just changing R61 was wrong so I thought I had missed something. I stand by my advice to put a smaller resistor in series with the 82k then, to try and get somewhere between 91k and 100k for R61. It’s easier and less annoying than trying to remove a trimmer. :P

  • I get it. thanks a lot, will try it ;)

  • but i’m still worried about the fact that the V/oct trimmer isn’t changing the scale but doing the same thing as the offset trimmer…

  • If it’s not adjusting the scaling then that is a problem… however if it changing the offset and the scaling then I’m pretty sure this is normal. That’s why you get the scaling right first (ignoring whether you’re actually getting the right note and concentrating on the interval) and then adjust the offset to get it back in tune. You might then find the scaling needs tweaking again, you’ll have to go back and forth between them making smaller and smaller adjustments until you’re happy (or lose the will to continue).

    The parallels between VCO tuning and setting the intonation on a stringed instrument are strong actually… the bridge is the V/oct scaling and the tuning head is the offset. Moving the bridge affects the scaling and also the overall tuning of the string, but the tension of the string affects where the bridge needs to be so you have to go back and forth.

  • changed R75 for a 20K and it indeed worked :) thanks a lot !

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