Feedback patches

Music & Patches
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I propose that in this thread we share and discuss our patches that use feedback, cybernetics, no-input and other related sound shenanigans. Anybody interested ?

Here is a first offering to start the idea :

The sound generation is based on a feedback path with a 4 channels matrix mixer, two VCFs (CF100 and the new “Serge” one), a drive, and a reverb (the new Klanghelm spring one, in Host). Then I use Transit a lot, to change a few parameters on some points in the feedback path, there also is a lot of mixers to mix different versions of the signals, and I added pings with slow LFOs on the two filters. Then I have two granular processors that receive the whole patch when its frequency content is high above 3kHz (High pass then envelope follower), and I modulate a few parameters (with slews) to avoid the static feedback sound invading the whole patch (the biggest culprit was the reverb).

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Feedback Satu, CF100, Serge VCF, TENS, LFOs, SEQ3, Matrix, Transit.vcv (13.9 KB)

How do you feedback ?

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I went through a phase of making feedback patches for a few weeks earlier this year. The method I used was to plug the monitor outputs from my interface into an old 4-track, then the 4-track outs back into the interface. The VCV patches just processed the feedback using filters and effects, but it made some interesting textures. Obviously you don’t need external signals to generate feedback, but the 4-track gave it a pleasing analogue quality reminiscent of really early electronic music from the 1950’s.

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I like the evolving texture you’ve got with that. And the feedback seems well controlled, which can be hard to do in these patches.

Here’s a more simple setup I did awhile back where the audio path is just a VCO & VCF. The VCO going through the VCF and also modulating cutoff and some panning. In return the VCF is used modulate quite a few params on the VCO. A couple LFOs in there to keep things moving. In the YouTube description I called it “an exorcism of buzzing robotic bees”. That description fits pretty good.

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4 Track ! Yes, a good while before diving into VCV and Eurorack, I use to play live with a 4 track recorder, tape loops (or longer ones with prepared material sometimes), two mixers for no-input mixed with other materials, guitar pedals and a synth. (for instance this is a live recording of this setup : Source - Live (Brouaa 2018) | Tana )

Any recording of the feedback patches that started outside VCV you could share ?

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Ok wow, thanks for sharing, I LOVE those sounds. I was trying to understand the feedback patch on the screen but no-can’t-do, right ? It is happening in your hardware and does not reflect on the control modules ?

Anyway I felt like the sounds were interesting, good sounding, and I would have liked a whole composition out of it !

Thank you !

Well yes indeed the challenge is imho to find an interesting balance between alive tones and some control. Then find ways to make it evolve in an organic way, without disrupting too much of the balance. It feels like half making music half observing a small closed biological system, one that you have the right to influence to see what happens. I love it !

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during this summer I had an out of body experience with this stuff :smiley: I still have to complete the little live setup before showing you everything :stuck_out_tongue:

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Well, wellity, I have using a Walkman to feed into a guitar effect pedals-Analogue delay, Reverb and A Multifx one [Sonicake]. Just been listening to them now, I’ll upload them to Soundcloud and put the link on here. Oh how I do enjoy feedback!

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More generally, using stuff beyond it’s intended and obvious use is interesting and fun. Exploiting more generalized characteristics. Often getting a deeper understanding of how stuff works and how to exploit options while exploring/experimenting.

And, yeah, feedback is fun.

Feedback is also the basis of several ‘physical modeling’ techniques. Think Karplus-Strong and/or feedback (comb) filtering FX (phaser/flanger) and/or to achieve resonance and implement resonators.

I did some crude feedback / karplus-strong / physical modeling experiments/videos some time ago when discussing Tabla/Sitar emulations.

Here’s a Karplus Strong like approach to Tabla using a mixer and tuned Delay in a near 100% feedback loop.

Here’s a short example of a feedback cycle through an EQ (effectively creating a resonator). You can can play with the ferquencies/bands and the bandwidth. Effectively a series of bandwidth filters where the feedback can go towards band level/bandwidth dependent resonance, approaching modal synthesis. Might inspire as a concept?

Here’s another approach using comb filters to create a resonator using feedback.

You could use 1 or more resonant resonant filters (e.g. bandpass) to create your own custom (resonant) filter bank. Using either or both the filter internal feedback and/or an overall external feedback loop. Various filters have various filter and resonance characteristics. You can insert all sorts of signal mangling anywhere in the audio signal path.

Generally, richer signals (including noise spectra) yield more interesting results in feedback loops.

That’s just some of my limited noodlings and thoughts…

But here’s some more advanced/inspiring examples of feedback and/or ‘no-input’ synthesis by modular/synth wizard Jakub Ciupinski

Here’s a mind boggling VCF Filter only patch

Here 's a n-times limited feedback loop through a filter (effectively serializing filters) with the option to insert stuff into the feedback paths (using polyphony modules for the looping). You could do the same in an unlimited full feedback loop.

Here he’s actually creating filters using mixer feedback, Exploiting the comb filter effect of the cable induced 1 sample delay (effectively phase shift).

Another tip is to check out HAINBACH (YouTube + albums + live performances). Hainbach uses all sorts of archaic and unusual gear (e.g. analog test equipment and obscure unusual musical instruments/gear) in creative ways. Often harkening back to days gone by (e.g. the experimental electronic music era of the forties/fifties/sixties, Pierre Schaeffer, Karl Heinz Stockhausen and such)

HAINBACH YouTube Channel:

HAINBACH Early Electronic Music Techniques Explained

HAINBACH Visiting Willem Twee Studios - a modern early electronic music studio

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Yes, feedback please … the more and the weirder the better :wink:

I use feedback loops in 99% of my patches wether it’s in Eurorack or in VCV!

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hmm, wanted to add some audio examples but realised that I can’t upload any mp3’s here :frowning: But as this is a cross post from a long lines thread, I might just add the link to listen there.

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Glad you liked it! Here’s a patch with somewhat-similar setup using only Fundamental components. I didn’t spend much time on it other than getting the patching setup but it’s in the ballpark if you’re looking for a starting point. A lot different character here than the clip I posted, as one would expect.

feedback_vcvnative.vcv (1.3 KB)

Note you will get very different results depending on the sample rate you set for Rack. I think this one actually works pretty good at a 24 kHz sampling rate, but obviously it’s missing a lot of the feedback events that are occuring at higher frequencies.

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@TanaBarbier I just got round to listening to that feedback patch, it sounds great! Some nice low frequencies with my sub switched on, and I liked the reverb on the higher sounds, very organic sounding. I also listened to 4-track performance, excellent stuff.

@brer_rabbit I liked your patch too, more of a ‘no input mixing’ sound.

I can upload some recordings if you’re interested, but feedback experiments aren’t always great to listen to so I’ve only used a small sections and sampled it. You can hear some on this piece:

I also made a YouTube short showing the process:

I was planning to revisit the feedback/4-track idea at some point so thanks for reminding me! The effects are the key point, any modulation usually works well, and I tried various filters patched polyphonically (effectively using 16 instances of the same filter). VCV Spectra made some cool sounds feeding back, and I also discovered with Bogaudio PEQ-14 I could set the bands to precise frequencies in a scale so it made pad sounds. There’s a lot to explore…

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Thanks for coming up with this topic, I’m really excited to hear people’s techniques! My attempts at it usually revolve around some sort of neuron or rungler patch – and lots of pinging! Here are some resources I came across which I find useful (some were recently posted to another thread):

La Synthèse Humaine’s YouTube series on cybernetics:

Simon Hutchinson’s video on artificial neurons and nonlinear mixing:

The manual for the ARC Artificial Neural Network eurorack module has some cool patch ideas, you can download it here:

Cheers!

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One more here just for fun. Building on the single VCO ↔ VCF feedback patch I posted earlier. Add in a few more Zoxnoxious modules so the entire audio is from that monstrosity. 3x VCO cards, 2 x VCF, and 1x dual VCO/VCF.

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Really nice !