The Ableton filter is great. I love the ms2 mode with 12db slope. If you pull the drive up it sounds really really nice.
A really interesting filter design to check out would be the xaoc belgrad. It has tons of ways to adapt the poles in different configurations
Also analog filters are really useful in feedback patches, where you mult out from the filter output and feed it back into the input with some attenuation. This allows you to control the resonance in some other way even on modules that don’t have a cv input for resonance. I’m curious to know how the Ableton filter would react in a feedback patch
be warned: DX7 / Operator-style FM is linear (adds to the frequency instead of multiplies) and through-zero (setting the frequency negative inverts the waveform). I think the FM input on Three Sisters is linear, but it’s unlikely that it would be through-zero.
also, 3Sis (and other filters capable of 1v/oct) is not temperature-compensated. so, one will work well and track musically, but they just aren’t as stable as a dedicated sine wave osc. so unless you want to keep stuff more-or-less monophonic (3Sis’s Span can help you fudge this), keeping a bank of oscillating filters in tune with each other is going to get frustrating quick.
this does make me wonder if there’s a comparable module, though, whose sine mimics but is temperature-controlled. i just have never been able to get the same timbral modulations from triangle core sines (really, DPO and STO) as i do 3Sis’s.
interesting interesting. this is the whole analog vs. digital thinking thing. as a player of instruments I am kind of used to multiple pitches going out of tune, but not every few minutes/hours. in what kind of timescale does 3sis lose the tune? I suppose it also helps to have a fine-tune knob.
and yea, the original iteration of the idea was max-only, as this is the-way-i-usually-do-things, but I’ve been starting to feel the direct-vs-indirect music interface thing, and the analog is imperfect thing. I love doing looping and delays in an indirect-interface way (where the link between interface and sound is more arbitrary/set by me), but my curiosity of modular direct-interfaces is growing.
I guess i just have to evaluate the validity of an analog thing which is as flexible as I want/need it to be.
sorry, I edited my previous comment to clarify – once warmed up, it doesn’t drift much at all. the overall tracking is a potential trouble spot when playing with others, since it isn’t really designed to do that as well as a dedicated osc.
I have a sequence running right now that spans two and a half octaves on both a DPO and 3Sis set to the same base frequency and there’s a noticeable detune (sharp) on 3Sis’s side once more than an octave up. using the Low output, as that is trimmed for 1v/8. again, super musical and expressive on its own – against other voices, though, it might not track as well as you’d like.
hmm, ok that does make more sense. things being in tune with other things is generally something I’m interested in so that is good to know before potentially diving into something.
I guess one alternative is using a hardware digital filter (4ms smr is what @jwm was using), though that complicates my oh-so-holy original intent for attempting hardware, and makes software yet again seem more desirable (which I’m pretty down with).
another solution that comes to mind I guess is using a control source (computer) that’s more flexible can be ‘tuned’ to what the filters feel like doing at the moment.
yeah things being in tune is generally something i am interested in as well, and, at the time, the smr was handy in that way. the comments made re: keeping banks of oscillating analog filters in tune is pretty on point and really, a dedicated sine oscillator with v/oct tracking and fine tune is where you wanna be (and yeah, theres a lot to be said about the purity of a filter’s sine wave vs and tri core osc’s sine, but…) but even then, especially with analog oscillators yeah, you’re gonna have drift…then you have the issue of the calibration of your v/oct source, power supplies, etc etc.
i know there is a lot of love around here for sisters and mannequins in general, but theres definitely some other (digital and otherwise) options out there that will get you into this territory, its just a matter of how you use/interface with them (ie my mentioned abuse of formant filters.) i’m sure a lot of people would look at my patches and go, yo dude, you know there is like, 2000 better ways to do this right? but it works for me the way i built it and the way i like to put my hands on things and patch i guess, and i just never enjoying mousing around in ableton that way (though i applaud those who can/do for sure)
also, i have no idea if i added anything to the small part of this conversation i’m connected to! i don’t forum very well, ha
in closing, here is a pretty great vid of a really expensive sequencer pinging a really expensive filter(s)
couldn’t ask for better conversation! the core of ‘less concepts’ (the album) was tackling these very questions and investigations. I haven’t arrived at any definite + unwavering answers, but I’ve learned a lot through the process and am really excited by what you’re exploring.
re: uvcf, 3Sis is designed to track 4 octaves as well – I haven’t futzed with re-calibrating, so will likely do that tomorrow to try and nail this down. if I can dial in both of mine to track along that range, I’ll report back.
you for sure did. sidenote: Barque Of Phosphor is gorgeous. so, if for nothing else, I’m really glad you stopped by
If the attenuator is a VCA, you can hook up an envelope detector to the filter output, invert the output and use it to control the VCA gain. A simple control loop that (with some tuning) holds the filter constantly at the brink of self-oscillation, with some interesting transient action, kind of like a hybrid filter/compressor. I used to do this with Serge before I sold my preamp/detector panels. This approach works in general for exploring other types of feedback, with delay lines, resonant EQ, and so on. it’s basically a way of extending the range of musically useful results while avoiding too much distorted chaos…
alright, fun things learned about re-calibrating 3sis for v/8:
temperature-compensated really means what it sounds like. touching the pcb threw pitch off pretty hard, since my hands were cooler than the module. wild. took about 10 minutes to re-stabilize after that first touch.
the fluctuations made it pretty hard to calibrate. the first time I nailed the 80 -> 320 check, 10 minutes later I was getting 80 -> 313.
eventually, after each adjustment, I let the module sit out of the case for a few minutes to re-stabilize and just kept trying.
after what felt like a million tiny adjustments, things evened out to 80 -> 320(ish)!
thinking over the helpful info Ezra provided about self-oscillating filters, I wonder if the Doepfer A-110–4 might fit this particular bill. it’s a VCO with a sine/cosine core, which seems like it’d be the best match for the sinewave generated from 3sis. of course, we lose the whole ‘filters as oscillators’ thing, but I think the FM pair between this and 3sis might get close to the same fun with more stability.
(this all feels insane, but also oddly necessary! thank you all for being on this journey.)
The octave trick that @Galapagoose mentioned for calibrating Mangrove might also help? It worked wonders for me. You sequence octaves rapidly while you’re calibrating and you can hear (or see w tuner) the pitch accuracy over the span. I attempted 3sis calibration once long ago and it was indeed tricky.
re: temperature calibration - this is a naive question for someone like @Galapagoose or others with better understanding of analog circuits than myself, but is there a reasonable way to retrofit temperature compensation?
my (incomplete) understanding is that it typically involves a special “tempco” resistor, right? I suppose I am curious if there is a possibility that some minimal rerouting/part replacing might be able to achieve temperature compensation.
the Doepfer suggestion is meant to explore options besides getting three, for the particular use case of creating complex voices through filter modulation (which 3Sis excels at) with/of clean sines rather than traditional frequency modulation.
super glad to learn that there is a legitimate (+ functional) difference between triangle-core sines and the sines of oscillating filters! that is honestly a huge relief.