Feedback instruments / no-input mixer / zero-input mixer

[Acoustic Interloper]

Attached are some interesting articles / papers from 2002-2005 on feedback-driven musical processes from Knut Aufermann's writings page, including a copy of *Resonance* that is entirely on feedback.

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Knut Aufermann MA Sonic Arts.pdf
Description:	Feedback Processes. Aufermann's MA thesis	Download (listen)
Filename:	Knut Aufermann MA Sonic Arts.pdf
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resonance_9_2_feedback.pdf
Description:	2002 issue of Resonance on Feedback	Download (listen)
Filename:	resonance_9_2_feedback.pdf
Filesize:	11.12 MB
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feedback_and_music copy.pdf
Description:	short 2005 wrote-up by Aufermann on feedback	Download (listen)
Filename:	feedback_and_music copy.pdf
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[robsol]

Wow, thank you Dale! Leafing through these now, looks like essential reading for me.

[blue hell]

Marked this post as "unread", had quick view into the PDFs, seems interesting indeed :-)

[Acoustic Interloper]

[Acoustic Interloper]

PS: My wife ordered me one of these for more Zero Input Mixing, for my 61st birthday last Tuesday, should be here this week. Jeremy and I were searching for likely candidates with features specifically for ZIM. He tracked this one down.

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AXS10Front.jpg
Description:	AXS-10 front
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AXS10-Back.jpg
Description:	AXS-10 back
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[Acoustic Interloper]

I've gotten through the David Lee Myers (a.k.a. Arcane Device) article in that Resonance magazine, found it so good that I tracked down a more recent interview from March 2014.

[Acoustic Interloper]

Quantum mechanical tunneling audio distortion device -- a 2010 patent application, linked, also attached below.

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US20100232614.pdf
Description:	Quantum mechanical tunneling audio distortion device US 20100232614 A1	Download (listen)
Filename:	US20100232614.pdf
Filesize:	207.93 KB
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[Acoustic Interloper]

Co-tunneling current and shot noise in molecules and quantum dots -- a 2005 dissertation with some potential applicability to these matters (attached).

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dissertation_thielmann.pdf
Description:	Co-tunneling current and shot noise in molecules and quantum dots 2005	Download (listen)
Filename:	dissertation_thielmann.pdf
Filesize:	1.6 MB
Downloaded:	2041 Time(s)

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[Acoustic Interloper]

In reading parts of the thesis (the last post above), I am forced to backpedal somewhat in my fixation on quantum-only sources of noise bootstrapping the audio feedback process.

I cannot copy text out of this PDF (password protected), so I took screen shots of 3 relevant paragraphs after searching on the string "classic". The electrical noise (in transistors & probably in "passive" components) may contain both classical (i.e., non-quantum) and quantum noise-generating mechanisms. They all get amplified going around the loop. Classical noise probably predominates.

Therefore, the inability of a digital algorithm to model this analog phenomenon adequately may not be due strictly to quantum noise generation, but also to hidden variables in classical, statistical noise generation such as thermal noise. The variables are hidden because there are too many variables in play to know and model, as in any complex (but classical) mechanism. I certainly don't propose that my 5-string banjo sounds employ quantum mechanisms. Digital modelers don't model acoustic instruments adequately because there are too many non-general variables in an instrument's sounds. Likewise with classical mechanisms for statistical electrical noise. Nevertheless, electrical noise remains a stochastic mechanism that a digital algorithm can only approximate. There is no need to invoke the quantum to get that digital infidelity from electrical noise. Hidden variables do the job.

I think there are two parts to this business.

1) How do you generate your initial "bootstrap noise"?

2) What do you do with it, going around the feedback loop?

My shiny red mixer arrived yesterday. I was too tired to do more than a sanity check, but I did manage to get transient sounds like running a wet finger around the rim of a wine glass, that (if I could get them to persist) I'd like to use as a background pad.

I am thinking of extremely long duration delays, maybe by running the feedback loop through a ChucK or Supercollider or Kyma patch. The mixer has some delay FX of limited time span, but I start to see how, if I can get a minimal (very low amplitude) signal to stick around long enough going through a very long delay with sufficient wet-to-dry, I can get 2 forms of oscillation going, the short-term "second order bootstrap tone" (the "first order bootstrap" being the electrical noise that starts the whole thing in the first place), and a "third order sustaining tone" which is just the second order tone sustained around a very long feedback delay.

One other thought for now. You sometimes hear no-input mixing's feedback arrangement referred to (disparagingly?) as "just an oscillator," but as I recall, LC and RC oscillators do not oscillate fundamentally from noise in the circuit, but rather from out-of-phase charge-discharge timing of a capacitor in tuned combination with an inductor or resistor. So, I think ZIM-as-oscillator is somewhat different. While it can use RC or LC filters to tune the feedback path, the bootstrapped signal is due to statistical noise fluctuations being amplified and filtered, in CONTRAST to a capacitor being periodically charged and discharged in conjunction with an inductor or resistor. Anyone care to confirm or refute? That makes playing it much more unpredictable and sexy than a conventional oscillator.

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[Acoustic Interloper]

I just finished the readings above. My next ZIM tutorial workshop will be much improved. Next performance too, no doubt.

The AXS10 will make its debut in the New Year's Eve webcast. The sweep-able mid-range eq is very useful for ZIM, as expected. The digital FX unit is very sophisticated, and a great complement to the more basic FX in my Yamaha portable ZIM mixer. NYE won't be a strictly purist ZIM set, but a good chunk of it will.

[blue hell]

[Acoustic Interloper]

I thought it might be instructive to look at some waveforms. I worked with low frequency pulses near the temporal boundary between distinguishable pulses and pulses that merge into bass tones.

This post shows the new Galaxy AXS-10 (the red mixer) with L and R saturated and the compressor fully engaged for my default.

I'll show the other mixers in posts below, so as not to run out of attachment space.

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Screen Shot 2015-12-27 at 1.30.01 PM.png
Description:	AXS-10 pulse train approximates a clean reverse sawtooth
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Screen Shot 2015-12-27 at 1.47.01 PM.png
Description:	Overdrive to add high frequencies. Note the asymmetry: The positives slopes have noise, while the negative slopes (including the drop to the trough, i.e., the "negative peak") do not.
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Screen Shot 2015-12-27 at 1.47.30 PM.png
Description:	Compressors off on this. Now noise on both sides of 0, but note the lack of noise on the decay from the peak. There is also a second, semi-periodic beat in the right channel.
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Screen Shot 2015-12-27 at 1.47.43 PM.png
Description:	Another without compressors. The right side second order beat is now a stable one-in-four.
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[Acoustic Interloper]

The Yamaha MG124cx, in comparison, has a basic pulse that begins to approximate a square wave, especially in the third pic, after turning off the compressors.

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Description:	Yamaha MG124cx basic pulse full compression
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Screen Shot 2015-12-27 at 2.07.16 PM.png
Description:	Yamaha MG124cx basic pulse full compression + overdrive adds "bird squeaks", like the AXS-10 only on the attack above the 0 line, but not on the trough attacks.
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Screen Shot 2015-12-27 at 2.07.36 PM.png
Description:	Yamaha with compressors off approaches a square wave even more.
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[Acoustic Interloper]

The little Alto ZMX862 is in a class of its own. Rather limited range of behavior due to lack of compressors or a second bus, and no FX (none of these pics use the FX units of the other two mixers), but it sure has a unique basic pulse and sound, with fairly good pitch range. It is especially throaty and interesting in the bass range.

All 3 mixers show asymmetry above versus below 0. Any ideas why?

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Screen Shot 2015-12-27 at 2.15.52 PM.png
Description:	ZMX862 basic pulse train. The rising edge to the peak "above 0" actually has overtones that go + and -.
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Screen Shot 2015-12-27 at 2.16.14 PM.png
Description:	Driving harder adds some squeaks. The fundamental "rising edge attacks" now generate overtones that completely swamp the fundamental pulse in both + and - directions, while the fall to trough is still a clean pulse. All 3 mixers show asymmetry a
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Screen Shot 2015-12-27 at 2.16.48 PM.png
Description:	Cranked it up it the point where pulses have merged into a drone, essentially. Obviously different pitch on L versus R channel.
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[Acoustic Interloper]

My New Year's Eve 3-Zero-Input-Mixer set (with post-processing in Live & also some electric banjo+ebow injected into a mixer feedback path in the middle section) is posted over here http://electro-music.com/forum/post-415491.html#415491 , along with some notes on the piece. Happy New Year!

[Acoustic Interloper]

I played and recorded the attached The Final Five as a 6-minute extension to my 4:15 Electro-Music 2015 sampler piece Baby's Electro Castanets in early October, as a ZIM piece that Michael O'Bannon looked into visualizing for inclusion in the SEAMUS 2016 planetarium venue at Georgia Southern University in February. Unfortunately, their projector requirements were substantially out of the ordinary, so the video part of this piece did not come to pass.

This is a combination of standard ZIM and also computer ZIM. Computer ZIM feeds analog outputs of the audio interface box back to its analog inputs, and processes the signals in software (Live in this case, although I have worked with ChucK in this way, too), so the signal source is still analog transistor noise. I am adamant about not generating the primary signals using software, for information-theoretic reasons that I have posted above and elsewhere. I see this aesthetic decision to be the same as feeding purely acoustic instrument signals into the computer, rather than using inadequate models that approximate acoustic instruments. I have no aversion to primarily abstract software-synthesized instruments that don't pretend to be something else like banjos.

I remember editing various different ZIM recordings together into the first 4:15 for the EM2015 sampler. The added 6:00 was all live performance, I think. All 10+ minutes are in the attached file.

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TheFinalFive.png
Description:	Adobe Audition waveforms
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TheFinalFive.mp3
Description:	The Final Five, copyright 2015 by Dale E. Parson, Creative Commons 3.0, distribute freely with attribution	Download (listen)
Filename:	TheFinalFive.mp3
Filesize:	9.29 MB
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[blue hell]

Very nice track that last one!

[Acoustic Interloper]

[Acoustic Interloper]

Here is a 12:39 workout Electro ZIM Fire that is an exploration of fire-like timbres. I fed the mono Aux Send from the red ASX-10 mixer into Live, through a graphic EQ, a grain delay, and a compressor. I used a simple delay before the compressor in a few short places in the 2nd half of the session. The EQ was to allow me to try to avoid excessive pops, especially in the high frequencies. The grain delay and the mixer itself were my main controls, grain mostly for pitch & somewhat for timbre. The compressor was a safety net to trap the pops. The output of that goes back to an input of the mixer, and a side tap takes it to the output of Live. The mixer runs an input through the usual gain, compressor, EQs, level slider, Aux level knob, and from there out the Aux send, completing the feedback path. I didn't use the main out or 2nd stereo bus of the mixer, nor any mixer FX.

I ran another signal path from the Yamaha MG124cx mono Aux send through an identical, parallel track in Live.

At various places this has sounds like a propane stove gas jet, a wood fire in the fireplace (complete with the sounds of crackling and the draft up the chimney), a forest fire, thunder, and some pure electro sounds. Runaway feedback got away from me a few times, so I edited those down to safe levels before posting. Waveforms & the Live channel appear below.

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FractalZIMFire.png
Description:	Waveforms
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ZIMWind16.png
Description:	Live signal processing in the feedback path.
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FractalZimFire21Jan2016.mp3
Description:	Electro Zim Fire copyright 2016 Dale E. Parson, Creative Commons 3.0, copy freely with attribution.	Download (listen)
Filename:	FractalZimFire21Jan2016.mp3
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[Acoustic Interloper]

Here's a little 15:30 of ZIM on the day before Valentine.

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AumManiPadmeZIM.mp3
Description:	Aum Mani Padme ZIM. The Jewel is in the Mixer. Dale E. Parson, copyright 2016, Creative Commons 3.0, copy freely with attribution	Download (listen)
Filename:	AumManiPadmeZIM.mp3
Filesize:	14.28 MB
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[Acoustic Interloper]

A few more papers, plus an excerpt from another playing around session.

The Burns & Burtner paper's abstract starts out:

[blue hell]

Nice tracks :-)

Will have to read the PDFs later.

[Acoustic Interloper]

Here is the ZIM recording from our planetarium gig last evening, myself, Genevieve Smith & Emily Hoch.

[Acoustic Interloper]

Steve Mokris posted videos of the March 19 planetarium performances here https://vimeo.com/channels/cse2016 , including the above ZIM+JAWS+Processing visualization piece.

[Acoustic Interloper]

Only one of these posted excerpts has to do with ZIM, but a friend and I at school are discussing spoken word. I had tentatively decided to edit just the spoken word portion of 2007's Ordinary Machinery, which I performed live at Electro-Music 2008 in Kingsport. When I looked at this 2007 EM thread, I realized that OM had been posted on Virb, that account long since dead. I've had an mp3 of the full piece posted on my university site for some years.

The ZIM piece These Voices is an excerpt from a practice session in August 2012 for EM 2012 the following month, posted in full here on EM. Unlike OM, I could not bear to cut away all the pre-spoken part of TV, because it is all lovely processed ZIM.

Sierra Parson wrote and performed the spoken word parts for both 2007's Ordinary Machinery and 2012's These Voices. Jeremy Parson plays bass on the former & recorded it.

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OM20072016Parson.mp3
Description:	Ordinary Machinery, 2007, spoken word part + virtual machinery.	Download (listen)
Filename:	OM20072016Parson.mp3
Filesize:	8.98 MB
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TV20122016Parson.mp3
Description:	These Voices, ZIM + spoken word part + surpise voices + sampled virtual voices, 2012.	Download (listen)
Filename:	TV20122016Parson.mp3
Filesize:	7.01 MB
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