North Coast Synthesis MSK008 Dual VC Octave Switch

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north coast synthesis msk008 dual vc octave switch

The MSK 008 Voltage-Controlled Octave Switch is a multifunction voltage processor. The module has two channels, each containing a whole-volt quantizer that maps its input to the nearest integer number of volts from -2 to +2; a three-position toggle switch that shifts the quantizer boundaries up or down by a volt; and a precision adder (with optional subtraction function).

If you simply route a pitch CV through one of the unquantized CV1 inputs, it can be a performance control, allowing easy transposition up or down an octave at the flip of a switch. That might be useful for VCOs without their own built-in octave switches. With no input signal, it generates a selectable offset of -1, 0, or +1 volts; feed that into an attenuated exponential FM input somewhere and you get the same tactile control over any other interval transposition you choose.

But the possibilities really open up when you start using more inputs. An LFO into the quantized input gives the effect of flipping the octave switch under CV control, keeping your hands free to wiggle elsewhere. Using the unquantized inputs, which are normalled across the two channels, you can transpose one sequence by another. The CV2 input can add or subtract, selectable during build by a solder jumper on the circuit board; in a default build, CV2 adds on the left channel and subtracts on the right, but do-it-yourselfers can change this selection, or design their own expanders to make it switchable on the fly.

Combining the two channels, with or without other utility modules, allows more complex melody-shifting effects. And it doesn't have to be just for oscillator pitch control. Switching fixed-voltage offsets on filter cutoffs also makes for great drops and timbral shifts. (And try putting the result through a slew limiter!) The default sum and difference configuration allows the module to act as a "mid-side" encoder or decoder. With other patching it can be a flip-flop or a wavefolder.

The MSK 008 is fast enough to work on audio. The quantizer is built from hardware comparators, without a microcontroller, and it can do simple bit-crushing effects across the whole audio spectrum. Each channel can also be a unity mixer for audio, with two regular inputs plus the output of the bit-crusher.

The MSK 008 is available as a pre-built 8HP Eurorack module or a do-it-yourself kit. Prices can be as low as zero (if you download the plans and source all the parts yourself). It has blinky red and green lights on it.

Two channels and multiple CV functions in a small space
Flash-style comparator quantization - no microcontroller
Through-hole design for easy hand construction and maintenance
Connectors between boards, and panel controls mounted on a board - no flying wires
No compromises on component quality: real aluminum panel, not PCB material, with colour printing; nickel and gold plating on the circuit boards; close-tolerance metal film fixed resistors; multiturn trimmers.
Fully open design - no lock-in

Specifications

8HP Eurorack synthesizer module, 43mm deep including mated power cable.
Maximum current requirements in normal use 45mA at +12V, 50mA at -12V. Reverse-connection protected.
Build difficulty: easy. All through-hole. Accurate voltmeter (or a tracking VCO and some way of measuring its frequency) needed for adjustment.