I talked with Andrew about if we should match the hardware frequency mapping, or stick with a more traditional 1V/octave, and we both decided that in terms of the cutoff knob mapping we would keep it linear. In the code I have a #define to switch the behaviour so the cutoff slows down and stops at the 12khz of the hardware, and this is the summed CV signal so also includes all modulation as well. If you keep the knob to 12khz max then you will match the hardware. The extra range is useful if you want to use the filter as straight out drive instead of having low pass occur as well like you do with the hardware, or when using the band pass or high pass modes to remove more of the signal.
(edit: if you watch the youtube video I show the difference this makes and point out this difference to the hardware)
Yeah keeping it 1v/Oct was a good call. Definitely a case where usability trumps accuracy. And yes, rewatching the video I saw this too. I thought I had watched the video to its completion before, but it seems I hadnāt.
The Lindenberg filters are good - check out Alma which some say is their favourite Moog ladder filter emulation in Rack (although Iām not sure to what extent it has been hardware modelled if any).
Itās currently in beta for rack 2 so check out the Lindenberg thread for a link.
Squinky Labs Stairway is another good Ladder and Valley Feline is a 101 filter emulation.
Nano Font is a digital version of a real hardware module as is Instruo I-o47 but again not sure if they have been modelled.
Also the Audible Liquid filter (which I think is modelled)
Some/most/all of these may be linear - apologies if so - but thought I would mention them in case you had missed one that might be useful.
Loving your A-124 Wasp model btw - I have the hardware and itās an extremely close match
My favorite Filters are Squinkys F2, Lindenbergs Valerie, Slime Child LP4 and Instruo Traigh. Will check out your new creation, when I find time again to do some patching.
This topic is super interesting! so many great info and great talk! thanks @andy-cytomic for hanging around! Super happy to work with you on this!
@steve has some good points, Alma is really great and very musical: itās quite Faithfull to moog but the magic is really into the ācalibrationā if there is such thing: when you push the drive just on the edge of saturation there is some magic happening where the sound goes from clean to drive in a random wobbly way. I thing there is also a short slew lim in the CV control of the freq, at least it sounds like it.
Audible liquid and eq filter are advanced modeling I believe, done by Alright devices dev. Liquid is one of the only filter in VCV that works as an multiphase lfo if you go down in freq, just like the hardware. Eq filter is crazy as well, if you really mistreat it, it can become a self oscillating voice. but both are hard on cpu
Oxilab and Slime child audio are great as well, and needless to say vult filters
The Slime Child LP4 seems to be very similar to the Liquid filter, except it uses ~50% less CPU with one monophonic channel, and less than 1/6 the CPU with all 16 polyphonic channels. However, it does not allow the self resonance to go into LFO territories By multiphase LFO, I assume you mean using Liquid LP4 and LP2 outputs to get the same frequency, but out of phase sines (and different magnitudes)
Running at 48 kHz sample rate, the Liquid filter seems to have an extra constant LPF with an extremely steep cutoff at ~20 KHz. I wonder if that is applied at the input. The LP4 filter does not have that high frequency cutoff. But other than that, the frequency spectrums of the output are strikingly similar.
itās expected, the moog ladder filter architecture stops self oscillate when itās low (at least on my eurorack ladder filter) but the the Liquid filter is more like a Serge filter, it can be used as LFO. The multiphase LFO is a serge trick unsing LP and BP outputs
Lindenberg Researchās Woldemar apparently has an analog warm-up built into it. Whether or not Alma or other modules in his line exhibit similar behavior is an interesting question. Iām not sure how much relevance it has to the questions in this thread, but it sounds like a cool detail to build into digital modules.
Given that it is marketed as part of the VCV collection, with a prominent position as the top most premium module listed on the main VCV site, no, I think the author is correct.
Cytomic is certainly given credit for the analog modeling on the web site. And this is speculation on my part, but Iām guessing others worked on the graphics and probably some of the nuts and bolts.
Itās a collaboration between VCV, Cytomic, and Doepfer. Iāll tackle all the more involved analog modelling, but pretty much everything else VCV is doing - including having organised the collaboration in the first place!
Once the final resonance mod code is approved it will be released, and Iāll upload the video showing it. Till then if anyone is interested here is the mod done to the v4 circuit board:
And here is an image with the mod applied to my hardware, I added a dual ganged switch to swap in both resistors at once, the resistors are up near the switch protected by heat shrink:
By multiphase LFO, I assume you mean using Liquid LP4 and LP2 outputs to get the same frequency, but out of phase sines (and different magnitudes)
