How to use Mutable Instruments’ Kinks

AKA Ava’s guide to rectifiers (and other such nonsense available on MI Kinks), this article will go through how a simple utility module can be extremely powerful to a modular synthesist. It can also be DIY’d very cheaply, and exists for free in VCV Rack.

The top section has a bipolar inverter, half wave rectifier, and full wave rectifier. The inverter, as you can well imagine, inverts stuff. Feed it a bipolar signal, you get a bipolar output. Feed it a positive-only unipolar signal, you get a negative-only unipolar signal output. The rectifiers are really cool though: both can limit signals to positive-only, but in different ways.

The half-wave rectifier (left one) will simply cut out any signal that’s negative. This is useful if you’re using the gate->highpass trick to get triggers/decay envelopes to ensure the triggers/envelopes are positive only, and depending on the filter can ensure you only get the rising edge to be the trigger/envelope. You can also use this as an asymmetric clipper by biasing the input signal. It’ll clip the bottom half of the wave if any part of it is below 0v, which means you can mix an oscillator with an LFO to get a modulated asymmetric clipper. It’ll also prevent cv, say from the S&H, from going below 0v – probably useful in sequencing, definitely useful in precision modulation of things with stepped voltages.

The full-wave rectifier (right one) will take whatever the negative signal is and invert it, sort of like a wavefolder. A bipolar sine wave will turn into a bouncing waveform, a bipolar square will turn into a narrow pulse wave, a bipolar saw will turn into a buzzy triangle, and a bipolar triangle will… just be a triangle, really. Can’t all be cool. Again, you can bias this to make a neat asymmetric folder. It’s also neat for processing random sequences (such as from the S&H) that may go negative to ensure all notes are positive cv, which quantisers tend to prefer (unless you have stages with alt firmware as a 6-channel bipolar quantiser, then it doesn’t matter #getstages).

With either rectifier, it’s important to note the key function is negative cv = bad. Use it to run any cv into unipolar-only cv inputs like on Noise Engineering stuff, control things to be unipolar only (and since it’s an active circuit, it’s limited to a little over +10v due to the rail voltage and voltage droop in the supply circuit and chip overhead), you can even use it as part of a logic system (using kinks’ onboard logic, mayhaps) to ensure binary signals are present. As with anything with 2 outputs, you can sum/difference/multiply/divide/etc. the two outputs to get even more fuckery.

Oh and, not super interesting, but the Sample and Hold has a white noise generator normalled to the input so you only need a trigger input to get random output. The trigger input is designed to take literally any signal and turn it into a 10ms pulse, and it can hold a voltage for an extremely long time before drooping. You can use anything as the input as well. My preferred thing is a periodic wave (like a saw or triangle) mixed with noise. This gives you a semi-random output, with randomness being controlled by the amount of noise mixed with the periodic signal. The periodic signal can also be a division of the trigger input to create arpeggios and other fun sequences, which again when mixed with noise can give you excellent semi-random sequences.

Another MI module on the books. Excellent. lol