Synkritis
Synkritis is firmware for the Alchemy Lab Eurorack module by Hermetic Modular.
Written by Jimmy Cuadra, A.K.A. Altered Perception Audio.
Current version: 1.0.0
Download: https://www.patreon.com/perceptes/posts/announcing-my-171573216
Video manual: https://www.youtube.com/watch?v=gMr-ZGbUQZE
If you use Synkritis, please consider supporting my work on Patreon.
Overview
Synkritis (pronounced 'see-gree-TEECE') is a dual comparator with logic operations.
Two inputs feed into two comparators. The knobs in the left column are for channel 1 and the knobs in the right column are identical controls for channel 2. Each comparator can operate in either single or window mode, determined by the bottom row of knobs.
Each knob provides visual feedback of its value via the LED ring. The off-arc LEDs below each knob indicate the status of the comparators.
WARNING: Currently, Synkritis does not work well on audio-rate input signals, due to limitations of the Alchemy Lab hardware + SDK. Synkritis will be updated to improve support for audio-rate signals if and when it is possible. If you want to read the technical details of the limitations, check out Alchemy Lab CV Outputs: Rates and Limits.
Single mode
In single mode (bottom knob turned counter-clockwise), a comparator's input is compared against a minimum voltage threshold set by the top knob. The top knob covers a range from -5V to 5V, with 0V at noon. If the input is greater than the threshold, 5V will be produced at the corresponding output. The knob in the middle row is ignored in this mode.
Window mode
In window mode (bottom knob turned clockwise), the knob in the middle row controls the amount of voltage added to the minimum threshold to create a maximum threshold. If the voltage at the input is above the minimum and below the maximum thresholds, 5V will be produced at the corresponding output. The knob covers a range from 0V-10V, indicated by a red light (orange/yellow in the CVD palette). A yellow light (light blue in the CVD palette) indicates the calculated value of the maximum threshold over a range from -5V to 5V. The maximum threshold cannot exceed 5V, regardless of the middle knob's position.
Logic
Four additional outputs produce signals derived from logical comparisons of the state of the two comparators.
The AND jack outputs 5V when both comparators are active. The OR jack outputs 5V when either comparator is active. The XOR jack outputs 5V when one comparator is active but not both. The FF (flip-flop) jack alternates its output between 5V and 0V on every rising edge of the XOR output.
State LEDs
The off-arc LEDs below the knobs show the state of the comparators. The LEDs under the knobs in the left column indicate the status of channel 1, while the LEDs under the knobs in the right column are for channel 2. All three of a channel's LEDs show the same value. If the comparator is active (i.e. outputting a high voltage), the LEDs will be white. If the input signal is below the minimum threshold, the LEDs will be blue. If the comparator is in window mode, and the input signal is above the maximum threshold, the LEDs will be red. The colors of the LEDs are slightly different when using the CVD color palette. More on this below.
Sample & Hold
Press 'Ch 1. S&H' (B1) and 'Ch 2. S&H' (B2) to toggle sample & hold functionality on and off for comparator 1 and comparator 2, respectively. When on, the comparator's input will only update when a trigger is received on the corresponding 'Trig' input. Between triggers, the comparator will hold the last sampled voltage as its input.
Motion recording
Hold the 'Rec' button (B3) and turn any knob to record parameter change on that knob. When you release the 'Rec' button, the motion you input will replay in a loop, beginning at the position the knob was when recording began. Turning the knob while the recording is playing offsets the starting position of the playback. Hold 'Rec' and move a knob with a recording to clear it and return to manual control.
Recordings can be up to 16 seconds long. Recording motion for longer than this will capture only the last 16 seconds.
Settings
Various settings can be configured via the web programmer or from the module itself. To enter settings from the module, hold the 'B2' and 'B3' buttons for two seconds. While in the settings, the 'B1' button cycles through settings pages, and 'B2' or 'B3' exits settings and returns to the main performance page.
Global settings
The first settings page is for global settings. The top left knob controls the brightness of the LEDs. This defaults to 30%, and it is recommended to leave it at this setting for optimal power consumption and heat generation.
To make Synkritis easier to use for people with color vision deficiency (CVD), there is an alternate color palette for the LEDs. To change palettes, use the top right knob. Counter-clockwise is the standard palette and clockwise is the CVD palette. This choice is retained in presets. When using the CVD palette, red is an orange/yellow, and blues are a lighter shade. Additionally, the maximum threshold indicator on the middle knobs will be the light blue instead of yellow.
Presets can be loaded and saved directly from the module. Use the middle left knob to select a preset slot. To save to the selected slot, turn the middle right knob counter-clockwise from noon. To load from the selected slot, turn the middle right knob clockwise from noon.
Jack settings
The second settings page is used to control what jacks J3-J6 do. The top four knobs select the behavior of these jacks, with the knobs corresponding to the jacks of the same relative position (top left = J3, middle left = J4, top right = J5, middle right = J6).
The options, sequentially from fully counter-clockwise to clockwise are: AND Out, OR Out, XOR Out, FF Out, Min 1 In, Span 1 In, Min 2 In, and Span 2 In. The first four are the defaults, as discussed above in the section on logic outputs. The last four are CV inputs, allowing external control of both comparators' thresholds with external voltages. You can mix and match any of these four outputs and four inputs and assign each of them to any of the four configurable jacks as needed for your purposes. This configuration is retained in presets. After reconfiguring jacks and exiting settings, the labels and help text for the jacks will be updated live in the web programmer.
When configured as a CV input, a jack will accept signals from -10V to 10V. To determine the final value of the parameter, the CV input will be summed with the position of the knob and then clamped to the knob's range.
Web programmer and additional documentation
To flash Synkritis onto your Alchemy Lab, use the web programmer on the Hermetic Modular website in a Chrome-based web browser.
After flashing, keep the module connected to your computer over a USB-C cable, and the web programmer will show a live readout of all the module's controls, as well as documentation for each knob, button, and jack.
Patch ideas
For patch ideas, take a look at the Compare 2 Practical User Guide by BRiES, available for download on the Compare 2 page on Joranalogue's website. Keep in mind that, because Synkritis doesn't currently operate on audio rate signals, only the patches from the guide that work with control rate signals will work.