Cytomic "The Drop" Resonant Filter

[andy-cytomic]

Ah, those are familiar! I used software for data approximation that used these approaches, although I'm guilty of not learning the inner-workings of algos too deep=) Would be quite exciting to see what you can do with it!
And I'm hopeful of many more high-quality plugins from you -- I think it is time to push the performance to a new level. I mean, I much happier use my i7 CPU to run 10 high-quality effects than 100 instances of plugins where compromises to cut down CPU usage were made.

As for Drop, I said that before in this thread -- I almost never use filtering of the type that Drop is, do you think this can be used to some tone-enhancement without using modulation?
I'm thinking of maybe using it in parallel, to get some "points" on certain frequencies by using resonances?

It sounds like you want a non-linear eq with variable drive, which is something I plan on doing in the future. The Drop is really for more in your face filtering, but it will have a wet/dry knob. All I can suggest is giving it a go when it comes out and see if it does anything you like.

[Caco]

andy_cytomic - As a dsp geek, I hope you are considering publishing your research and findings as I for one would find it a very interesting read

[mystran]

The math that Andy is discussing for the upcoming filters is different than the standard techniques of transforming analog filters into digital algorithms. It looks like he is attempting to address, not only the issues with stability at all cutoff frequencies (that are a big problem with, say, state variable filters), but the performance of the filter when time-varying. I am really looking forward to hearing the results.

I would like to claim that the issue with stability when it comes to the usual SVF is largely just a result of over-simplification in coefficient calculation; the structure itself is perfectly stable for any stable transfer function, but the way the coefficients are normally calculated doesn't lead to stable transfer functions for the full range of the design parameters. Like I've said before, you can pick any stable set of biquad coefficients and map them to a stable Chamberlin with the desired transfer function (though last time I suggested this, someone argued that the conversion is unacceptable since you need a square root). In fact I use a (very slightly modified) Chamberlin for all my biquads (most of which are designed with the usual cookbook formulas or something similar) now because of the nice numerical properties.

The question of time-varying behavior is kinda real though.

Unacceptable because of one sqrt? This is the kind of mentality that is keeping audio dsp in the dark ages. Are they trying to run this stuff on Commodore 64?

I did investigate a slightly modified Chamberlin algorithm, and with the help of Magnus Lidström came up with a normalising factor of 1 / sqrt (function of g and k) - I don't really count one division and a sqrt per sample much of an issue in terms of cpu since I'm interested in high quality filters. Although the filter is stable in linear form, and it does match the attenuation of an analog biqaud at cutoff, it turned out to be a big dead end, since as soon as you apply circuit non-linearities the normalisation breaks down and becomes unstable, and it didn't sound right when modulated either.

Actually personally I wasn't even interesting SVFs as such. I just wanted a filters structure that would behave nice in general. I think I was using ladder/lattice structure at that time, but wasn't completely happy with those. So I was just basically looking at generic 2-poles to see how to get nice gain staging and it turns out a modified coupled form (which is essentially more or less like a Chamberlin) is one such nice structure. Once I tweaked it a bit to get rid of singularities I had a filter even more like Chamberlin.

As far as non-linearities goes, yeah, trying to limit it as if it was a circuit model just fails miserably. It's certainly possible (and I did it for Sweep, which was a sort of proof of concept for that stuff) to put in saturation that keeps it unconditionally stable (or bounded for unstable coefficients), but it doesn't make much a circuit model because like you said, trying to transfer analog non-linearities over just makes things blow up.

[Nokenoku]

Seems like my question was missed, so again:

How exactly will the envelopes of "The Drop" be?
Will there be loopable multipoint-envelopes (preferably with multiple patterns, which can be accesses by MIDI-notes or just automation) or just a single MIDI--triggered envelope?

[penguinfromdeep]

i wish more developers were like Andy!

[andy-cytomic]

Seems like my question was missed, so again:

How exactly will the envelopes of "The Drop" be?
Will there be loopable multipoint-envelopes (preferably with multiple patterns, which can be accesses by MIDI-notes or just automation) or just a single MIDI--triggered envelope?

Woops, sorry about that! There will not be any loopable multipoint-envelopes with multiple patters in The Drop. The focus of The Drop is on tone and easy of use, and I want people to be able to tweak the knobs in musical ways so they can easily "play along" to whatever audio is coming through the filter, rather than getting bogged down in programming.

There will be a powerful LFO with exponential to inverse exponential shapes which is capable of audio frequency rates. You will be able to automate all aspects of this LFO, and you will be able to retrigger it in various ways, so you can build up complex and precise patterns from programming this automation in your host if that is what you prefer. There will also be an extra audio input just for modulation, so any plugin that can generate audio or modulation signals will be able to control The Drop.

[@midnight]

will it add latency? it sounds like you want people to be able to play with it real time so I'm assuming it will be zero latency.

[andy-cytomic]

The filter will work without oversampling, and so add no latency. If you want lots of drive and resonance then you may want to engage the oversampling, which will add latency, or run you whole project at a higher sample rate than 44.1 kHz or 48 kHz and every plugin will benefit from the increased frequency range.

[Nokenoku]

Woops, sorry about that! There will not be any loopable multipoint-envelopes with multiple patters in The Drop. The focus of The Drop is on tone and easy of use, and I want people to be able to tweak the knobs in musical ways so they can easily "play along" to whatever audio is coming through the filter, rather than getting bogged down in programming.

To me MPE are very easy to use, but I see your point with classic knobs for realtime tweaking and automation.

There will be a powerful LFO with exponential to inverse exponential shapes which is capable of audio frequency rates. You will be able to automate all aspects of this LFO, and you will be able to retrigger it in various ways, so you can build up complex and precise patterns from programming this automation in your host if that is what you prefer.

So you can use the LFO as some kind of envelope?

I'll just wait for the plugin I guess. After listening to the audio-demos I'm very excited to play around with it.

[meloco_go]

It sounds like you want a non-linear eq with variable drive, which is something I plan on doing in the future. The Drop is really for more in your face filtering, but it will have a wet/dry knob. All I can suggest is giving it a go when it comes out and see if it does anything you like.

Oh, non-linear eq with variable drive make me salivate=)

Andy, would I be able to set up Drop as sort of "noise-gate" for high-frequencies? Here's the idea -- on a tom-track there's also very long ring, so ordinary gate often cuts it either too-much or you have too-much cymbal bleed. Some people use LPF with variable corner frequency which is triggered by audio signal -- at the transient the frequency goes up to pass the attack, and on the ring-out it goes down to cut cymbal bleed.
Would I be able to set up Drop to do that?

[andy-cytomic]

Oh, non-linear eq with variable drive make me salivate=)

Well I plan on releasing such a beast, so hopefully you won't have to wait too long.

Andy, would I be able to set up Drop as sort of "noise-gate" for high-frequencies? Here's the idea -- on a tom-track there's also very long ring, so ordinary gate often cuts it either too-much or you have too-much cymbal bleed. Some people use LPF with variable corner frequency which is triggered by audio signal -- at the transient the frequency goes up to pass the attack, and on the ring-out it goes down to cut cymbal bleed.
Would I be able to set up Drop to do that?

The Drop will hand that with consummate ease

[@midnight]

Andy!

http://www.kvraudio.com/news/camel-audi ... 1-25-17401


Are these new Alchemy filters the same/similar to The Drop?

[valhallasound]

Andy!

http://www.kvraudio.com/news/camel-audi ... 1-25-17401


Are these new Alchemy filters the same/similar to The Drop?

Andy wrote this in an earlier post in this thread:

apparently, there's some Cytomic filters included in the new Alchemy update.

"Alchemy 1.25 is now available to download from your support account. This update features enhanced analog modelled filters by modelling experts Cytomic, an additional skin by biolabs and support for remote control with Alchemy Mobile."

I helped Camel fix the filters in Alchemy, but the design and analog modelling was done by Antti Huovilainen and not Cytomic. There were some implementation problems which meant Camel had to clip the inputs to the filters to keep them stable. My brief was to fix the filters so they could remove the input clip, but preserve the original sound as much as possible to maintain patch compatibility, and also be as efficient on cpu as possible. If I was involved in the design process from the beginning the outcome would be different to what is there now. But, the tone has been improved, and the cpu use reduced, and they are stable, so it's a big win for all Alchemy users, which includes me. Part of the reason I wanted to help out was because I wanted the filters improved for my own use

If you are interested in the best analog modeled filters I have designed thus far that are currently for sale in a product they are in Synth Squad, which I did for FXpansion. The filters in The Drop are a completely new algorithm that offers much better results, but at the cost of more cpu. These new algorithms are much closer to analog filters since they have instantaneous feedback, and handle fast modulation very smoothly.

[@midnight]

The filter will work without oversampling, and so add no latency.

I see. What about for example your Synth Squad filters, Synth Squad can be run with oversampling, but the latency is still zero, right?

[andy-cytomic]

The filter will work without oversampling, and so add no latency.

I see. What about for example your Synth Squad filters, Synth Squad can be run with oversampling, but the latency is still zero, right?

When a plugin is oversampled with anti-aliasing filters it will always introduce latency. The filters in Synth Squad only go up to 44100 / 4 = 11025 Hz without oversampling, with x2 oversampling they go up to 44100 / 2 = 22050 Hz, but at the cost of extra cpu and a small amount of latency. The oversampling filters in Synth Squad are minimum phase half band filters, so the latency introduced depends on frequency. The oversampling filters in The Glue are linear phase, but I am looking into adding a minimum phase option as well for The Drop since sometimes it is more important to have lower latency even if it does cause non-linear phase changes.