TX81Z Patch Degrader with Interpolation

Posted on August 10, 2015 by John CS Keston

This quick demo illustrates how TX81Z Patch Degrader is interpolating between previous and newly generated parameter values. TX81Z Patch Degrader is a Max for Live MIDI effect that chips away at patches on the TX81Z by randomly changing (or degrading) parameters at a specified rate. What makes the process interesting is that it is possible to ramp up or down (interpolate) to the new value rather than changing it instantaneously.

To create the Max for Live MIDI instrument I started with TX81Z Editor 1.0 by Jeroen Liebregts who was kind enough to share his work on maxforlive.com. I added in the degradation process features and made some adjustments to the interface to make room for the controls. Once I get things shaped up I’ll be happy to share the patch if anyone is interested.

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The features I added are visible in the second panel of the TX81Z Patch Degrader Max MIDI effect. I’ll describe them from the top down:

Level bypass prevents the operator levels from being included in the degradation process so that the sound doesn’t completely die out.
When the interpolate switch is on new values (as long as they have an adequate range) are ramped up or down to the new value based on the rate.
Loop causes the degradation to continue indefinitely by reshuffling after all 73 parameters included have been degraded.
Free/sync toggles between changing the parameters at an arbitrary pace set by rate, or note divisions based on the project’s tempo (therefore sync will only degrade while playing)
Rate adjusts the rate of degradation when in free mode, and the time it takes to ramp up or down to new values when interpolate is on. Rate is milliseconds and ranges from 15ms to 2000ms.
Below rate are the note durations for sync mode ranging from a 1/128th note up to a dotted whole note.
Finally the degrade button starts the process while interrupt stops everything so when you hear something you like you can save the patch on the TX81Z.

The TX81Z has a fairly small buffer for MIDI values, so spraying values at it too quickly will generate the “MIDI Buffer Error”. However, even after getting the error it will continue listening to the incoming data, so even though it might be skipping a parameter here and there it lets me keep throwing things at it. The video below shows how the LCD display responds to the stream of values coming at the machine.

TX81Z Patch Degradation with Interpolation! #glitch #fmsynthesis

A video posted by John Keston (@jkeston) on Aug 8, 2015 at 1:31pm PDT

I’ve saved quite a few very interesting effects so far and have nearly run out of the 32 patch positions available on the unit. Perhaps the next step is to add a library feature especially since I’m not thrilled about the idea of saving patch banks to cassette!

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How Kindohm Makes Wicked Breaks in Tidal

Posted on August 4, 2015 by John CS Keston

It you’re familiar with live coding (performing music through the process of writing code) then you’ve probably heard of Mike Hodnick (aka Kindohm). Mike and I have had the pleasure of performing together on several occasions and I’m thoroughly impressed with his technique and aesthetic. In this video Mike goes in-depth on how he creates breakbeats using Tidal, one of several languages commonly used to do live coding.

Korg Volca Keys Delay Circuit Noise

Posted on October 12, 2013 by John CS Keston

KorgVolcaKeys

I have had the Korg Volca Keys for a little over a week and have gotten quite comfortable with the unit. The feature set can be learned in a matter of minutes, but the sonic range of the instrument is impressive and much more broad than I expected. The strength of the Volca Keys is in the modes: poly, unison, octave, fifth, unison ring, and poly ring. The sound I posted earlier, for example, demonstrates the poly ring modulation mode. Lately I’ve been enjoying syncing the Volca Keys with my DSI Tempest and Korg Monotribe, but more about that later.

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Of course a hardware analog synth that exhibits the diminutive size and cost that the Volca Keys does is bound to have some limitations. From my perspective the most obvious limitation is the quality of the onboard delay. According to Korg’s block diagram the delay is the final circuit in the signal flow. Therefore, high frequency noise coming from the delay can’t be rolled off with the filter. The noise is most obvious when playing a sound that is programmed with the cutoff frequency most of the way down, the delay time at the slowest setting, and the feedback at the highest setting.

To illustrate the noise introduced by the delay circuit I created a few versions of a simple test sequence. One without delay, one with the internal delay, one with Ableton’s Simple Delay, and finally one with my Electro-harmonix Memory Man Delay. The sequence sounds pretty clean on its own, but buzzy, high frequency aliasing becomes audible when the Volca’s delay is introduced. In comparison, Ableton’s Simple Delay doesn’t add any noticeable noise, while the Memory Man adds a little noise (and pleasant chorusing), but nowhere near as much as the Volca delay.

Korg Volca Keys Sequence with No Delay:

Korg Volca Keys Sequence with the Internal Delay:

Korg Volca Keys Sequence with Simple Delay:

Korg Volca Keys Sequence with Memory Man Delay:

Some might find the buzzy delay noise desirable at times. To me it sounds more-or-less like a cheap, digital delay circuit that uses some down sampling and/or bit reduction to handle the memory requirements for the repetitions. I have also noticed that the filtering on the delay trails is significant. Cranking up the cutoff and lowering the attack, decay, and sustain on the EG produces obviously muffled delay trails. All of these limitations are not that noticeable when you’re using the Volca alongside two or more other instruments, but I plan on using my Memory Man as an alternative to the on board delay when it’s convenient to do so.

Machine Machine Touchscreen Instrument

Posted on June 26, 2013 by John CS Keston

Machine Machine (2013) is a 32″ touchscreen installation that functions as an electronic instrument. Granular synthesis is used to loop “grains” of sound and video at variable lengths and frequencies. These parameters are based on the y-axis of the touch point on the monitor. The x-axis determines the position of the grain within the timeline. The piece was exhibited last month at the Northrup King Building in Minneapolis during Art-a-Whirl and for Visual Storage; the MCAD MFA thesis exhibition.
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Spectral Tablature (2013)

Posted on May 13, 2013 by John CS Keston

Spectral Tablature is a series of collaborative installations that explore sound generated through visual processes. Sound is recorded or synthesized using common techniques then converted into images called spectral analysis. These forms are re-interpreted as a visual artifact then converted back into sound. For each pair, or “duet,” the similarities and differences in tone and texture can be heard as well as seen in the work. This series, along with two more of my installations, is currently on display for my thesis exhibition at the Northrup King Building in Minneapolis. Please read on for images and descriptions of each pair of prints along with the audio.
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