An Annoyance of Grackles

Like the Noise Ring, An Annoyance of Grackles was the brainchild of a deep collaboration. But in the case of the Noise Ring I originated the fundamental core and Grant Richter saw a horizon beyond my concept and vastly expanded the design. In the case of the Annoyance of Grackles. Martin Freeman showed me a fundamental core and I saw potential way beyond his original conception. I was inspired that Grant saw so much in an idea I started, and it made me very proud and happy that I could ‘pay that forward’ with Martin’s very fertile idea.

… and that idea is a doozy!

First, here is a link to Martin’s version of the Grackler .

and below is a diagram of his fundamental concept:

[Please refer to the diagram above] There are 4 VERY wide-range VCOs (the 4 semicircles). Each VCO outputs a square-wave and a ramp wave. The square waves form the inputs of a 4-Bit DAC. The DAC outputs a constantly changing staircase-shaped control voltage. (represented by a gray line). The VCO ramp wave outputs are used to control (throttled by a knob) the next VCO in a daisy-chain. These control paths are represented by the red lines. All of the outputs above can be tapped for audio or control signals. The ‘red’ daisy-chain arrangement alone has the potential to create very complex turbulent patterns. But Martin went a step further and routed the DAC output through a ‘throttle’ knob to all the VCOs too. (represented by the blue lines)

This idea really sings.

… and then the expansions

On the right-half of the Control Surface the 4 ‘classic’ Grackler daisy-chain controls are arranged in a diamond-shape in upper right. Below them, are the 4 expanded feedback controls (knob#’s 5, 6, 8, & 11 in the block diagram) surrounding the ‘Big Knob’ (#7) which is an offset voltage that adds to all 3 of the feedback control paths.

Martin used the VCO on a Phase-Locked-Loop chip for his VCOs. My first expansion idea was to exploit the phase comparator capabilities of a Phase-Locked-Loop to generate additional controls within the core circuit daisy-chain. I also decided to used an 8-Bit DAC vs. Martin’s original 4-Bit DAC. All of this work is in the large box at the left of the diagram labelled ‘Grackler Circuit Core’.

This expanded core is bristling with control voltages and audio signals and at the expense of sober technical exegesis … I just went nuts with all that.

I added two resonators, one on the main audio path, and another on a octave-divided audio path.

And more importantly, I added 2 additional types of feedback to Martin’s original DAC-feedback scheme. (these are controlled by knobs 6 & 8 in the diagram above) raising the number of feedback paths to 3. Referring to the control surface photo above, on the right-half of the Control Surface the 4 ‘classic’ Grackler daisy-chain controls are arranged in a diamond-shape in upper right. Below them, are the 4 expanded feedback controls (knob#’s 5, 6, 8, & 11 in the block diagram) surrounding the ‘Big Knob’ (#7) which is an offset voltage that adds to all 3 of the feedback control paths.

Design-wise, I went a little nuts too. I had the old RCA 8BX6 radio cabinet with an irresistible roll-top panel just begging to be recalled to active duty. And in Martin’s design, there is that single knob in the scheme that feeds the DAC output back into all the VCOs and that knob influences every parameter of the core. So I used a big knob (#7 in the diagram) I’d been saving, and surrounded it with the added feedback knobs . My intention was to make it possible to do an entire performance by using the Big Knob 97% exclusively. I was also very resistant to the thought of putting patch-points and spaghetti on that elegant old cabinet. But the system DOES require a flexible scheme to configure the overall parameters of how it behaves and a patch-panel is by-far the best solution for that. So I implemented a patch panel and hid it behind that handsome & clever roll-top panel that the RCA designers provided. Problem Solved.

On the ‘front’ of the electronium (the part that usually faces the audience) I implemented 6 output jacks that can be used simultaneously. The are shown on the block diagram as the numbered circles. These jacks are the audio outputs, arranged from left to right, they tap the sound at 6 stages of the processing form the leftmost which is the sound of only the ‘grackler’ core to the rightmost which is the sound after it has been through every processor that I added. Above the six outputs is an input jack (Ext.In) and an attenuator knob which allows output #6 (rightmost) to be swapped by a flip-flop under the electronium’s control between the electronium output and any outside audio signal.

An explanatory Video courtesy of Hearding Cats Artists Collective.