V/Oct Patches for Witch

OWL Witch
#1

Hi - I would like to use my Witch as sort of a macro standalone extra oscillator for my Eurorack system. It seems to me that the “stock” oscillator patches for the Witch - i.e., SubTract, Vosim and Wavebank - track v/oct very well (I have tested this using a Korg SQ-64 sequencer connected with pitch and CV/gate to the Witch). However, any other oscillator I have tried loading onto the Witch from the OWL library does not seem to precisely track v/oct, even if it says it will in the patch description.

Can someone please let me know if, in your experience, any of the other oscillators in the patch library would track v/oct well on the Witch? I know that most, if not all, of these oscillators were originally designed for the Lich, and I am wondering if that makes a difference here. For example, I would love to use MorphingOscillator, PolyBlep or Synth Voice, but just can’t seem to get these to track accurately at all.

Thanks in advance for your help!

#2

Witch was intended to be used as a synthesizer or audio processor, so its audio inputs are AC coupled. This means that any DC signal (like what you get in case of controlling with V/Oct signal) is high pass filtered in hardware. Normally OWL patches take V/Oct control from the audio inputs. IIRC, stock Witch patches use one of its parameters for V/Oct control instead.

There are a few workarounds if you absolutely need it. First, a few capacitors can be unsoldered to make its audio inputs DC coupled, it might be also necessary to build a modified firmware that won’t enabled digital filtering from audio codec that is also used on Witch. So that’s a rather complicated solution.

Alternatively you could modify your patches to send V/Oct signal as a parameter rather than as audio signal. In the later case you would have to apply correct offset/scaling and results would be less precise, but the same approach is used in Oneiroi, for instance.

#3

Thank you very much for your response! This is very useful (I was thinking I was going crazy for a time). I am certainly not going to muck around with the audio inputs, so my next question is how difficult would it be, in theory, to modify the Lich oscillator patches on the website to operate as the stock Witch oscillators - in other words, to send V/Oct as a parameter instead of as an audio signal? Are the stock Witch patches available for download? I only see them in the main Witch editor, and cannot see the code (unlike the patches shown in the OWL patch library). How difficult would it be to copy the V/Oct input code from the stock Witch patches and put it in a Lich oscillator patch instead?

Thanks again for your help!

#4

Witch patches are here

There’s an example for computing “pitch” parameter. AFAICT it simply scales parameter to map frequency corresponding to -2.5V…+2.5V range. It looks like changing patches that have a “tune” parameter to use the same code for it might work, maybe base frequency would require adjustment for a note C in octave that suits you better.

#5

Thanks again!

That link to Witch patches doesn’t seem to include all of those listed here (which I know track V/Oct correctly on the Witch). Do you know of a way to download those (SubTract, for example)?

In addition, would you mind pointing me to the line in the code you linked that computes the “pitch” parameter (I don’t see it)? Where in this patch is it looking to the Witch CV input? I am completely inexperienced in programming, so would very much appreciate your additional help here. In addition, if I wanted to edit one of these patches, would I simply use Notepad or something similar and save it as a .hpp file?

Thank you!

#6

I think there was some renaming and SubTract is in “PolySubPatch.hpp”.

If you’re new to programming and want to use Witch and OWL to learn it a bit, you should start with the docs. It may be easier to understand how to use Puredata or FAUST compared to C++.

#7

Thanks, I will do that. In the meantime, would you be able to answer the above questions, if you have time? I would really appreciate it.