4/9/26 Metasonix RK7 RK2 RK8 + Beers Melakarta & DAC + ALM Pamela’s New Workout + Alesis MIDIVERB II

video upload by Cfpp0

This is the first post to feature the Beers Melakarta.

"Feeding the Beers DAC and Beers Melakarta several triggers from ALM Pamela’s New Workout, and then modulating the pitches of the two Metasonix RK7 VCOs and the CV on the Metasonix RK8 Filterwall. Gated reverb from the Alesis MIDIVERB II."

"The idea for this module came from my friend Rodrigo Kendrick. He was a bit burned out on western tonal structures, and had recently missed out on an electronic lehra machine in a facebook marketplace deal which fell through. These machines are a kind of practice tool for carnatic musicians that plays a wide variety of different raga. Think that 'casio auto-chord' function on old casio keyboards, but for carnatic music.

Unwilling to wait for another one to come up on the used market, he did some cursory research, and sent me an early-morning design document, expanding the functionality of DAC with a scheme of two rotary switches and one toggle switch to select the pitch sets for all 72 Melakarta ragas and specified a clock input that would run up and down the selected raga in ascending then descending order, with the ability to turn around or reset on command. In theory this would allow the complex rhythmic and sequence rules of the raga to be implemented with external logic and sequencers, but still give the module enough sequencing functionality to explore the pitch sets of these raga on it's own.

I got excited and went a bit silly 'helping' until we had shoehorned in a pile of other features like binary addressability of the selected swara (interval), gate outputs for each swara, an 'inhibit' input that mutes the transposition voltage while the clock continues in the background, CV controlled halving of the clock frequency, extra +1oct input, and the logic-inverting toggle switches from the DAC on several inputs.

This design is all analogue using discrete MOSFETs and 0.1% tolerance resistors in a weighted DAC driven by a 4000-series CMOS based sequencer.

Yes, it might have been simpler to use a microcontroller."