Check out FM of Filter-Cut-Off with VCO3 at audio rates

[SoundRider]

Audio rate FM of the filter cut-off frequency can create very expressive formant like sounds, which is not possible on every synth, but on the MatrixBrute 

Frequency modulation of filter-cut-off is not a new trick, it's quite old-school. But only a few non-modular analogue synths of the past support audio-range FM with keyboard tracking VCOs (AFAIK Moog Voyager, or ARP Odyssey, maybe some more), and now we have the MatrixBrute.

The basics are quite easy.

• Use a tone in the low frequency range and
• FM the filter at least with a frequency, which lies 2 or better 3 octaves above this tone.
• Now increase the filter resonance, the filter-FM-intensity, and sweep the cut-off around. This should already generate some rough idea, where sweet spots could be. They sound like changing formants, particularly, if the cut-off is sweeped back and forth.

IMO the effect is most expressive, if the filters are in 12 dB mode.

The generated sound is defined particularly by:

• the basic timbre of the sound generating VCO or VCOs
• the filter "type" and "sub-type" (try out SP and Ladder and all the modes)
• the position of the cut-off frequency
• the position of the filter resonance
• the position of the Brute-Factor !!!
• the frequency relation between the sound generating VCO (here VCO-1 and/or VCO-2) and the FM driving VCO (here VCO-3)
• the FM-intensity
• the waveshape of the modulating VCO

Since the generated sound is sensitive to all of of those parameters, there is much sonic territory to explore ... and I even haven't mentioned, what we can do with the mod-matrix ... formant-frenzy ahead ... 

[robst247]

Thanks for the suggestions, SoundRider. I've just spent a couple of hours experimenting with all kinds of variations on your basic idea. In some cases, the results were enhanced by also modulating the filter with a little noise (using the VCO1<Noise>VCF1 knob turned between one and two small divisions to the right).

Do you know of any other creative uses of noise modulation of filter cut-off frequency? If so, please share them here.

I'm finding that the MatrixBrute has quite a long learning curve, which is great, because that means a lot of ear-buzzing experimentation lies ahead. 

[SoundRider]

Yes, adding noise as a filter modulation can always make a difference.

I use noise for filter modulation, if I want a kind of instability at the beginning of a sound. This can give us a sound like the breath before a flute-like sound develops to full volume, or this bubbling noise, which is at the beginning of brass instrument sounds, it can also become a kind of pluck-noise, which is in the transient of string sounds. The MB is great providing four different noise sources and we can select the best suited for the sound in our minds. As you may have guessed, I often use those modulations only short-time and the MB supports this particularly well by providing the FM-modulation to be modulated too. For this I use the third envelope or a single shot LFO, which is triggered by the gate.

Filter modulation is also excelent, if we want a certain roughness in the audio. If done right, it's not a noise or a hiss anymore, but some kind of fluctuation giving a particular kind of life to the sound. The effect depends on what noise we use and how much we apply.

But there is more ... particularly with the options provided by the MB filters ... and the modulation matrix. A burst of noise, or a increasing/decreasing noise, or even a more or less "stable" noise level can do interesting things with the filter, if we use the drive and the BruteFactor too. There are so many possibilities

[ijt33]

How would I modulate the filter at those rates - are you using the LFO or routed an oscillator to the filter cut off with the CV sockets on the back of the machine ?

[ijt33]

Ah... found it .. Audio Mod Knob 3 !   Silly me.  Love it !