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!