The RYO Aperture is a vactrol lowpass filter and VCA module inspired by the much beloved 292 Lopass Gate from the Buchla 200 series modular system of the 1970s. However, rather than being a straight up clone, the Aperture is a newly developed and reworked design for eurorack modular synths.
Aperture can be used as a 12dB lowpass filter, a VCA or a combination of the two similar to the 292 but also adds a new switchable resonance circuit. This solution gives you no less than 6 different characteristics!
* Non resonant lowpass filter
* Resonant lowpass filter
* Both: Non resonant lowpass gate
* Both: Resonant lowpass gate
* 6dB variety of resonant lowpass gate in the VCA mode with resonance on.
The resonance goes from smooth and twangy to increasingly bubbly and acidic to wild and untamed howling towards the end of the pots range. The self-oscillation also lends itself well to creating kickdrums, toms and other percussive sounds.
The result is a very wide range of sound shaping possibilities, from the classic resonant filter sweeps of east coast to the plucky acoustic timbres of west coast synthesis and everything in between.
Also added is a unique "Klang" function. The Klang input generates a decay slope from a trigger, the shape is very steep in the beginning and quickly smooths out to a nice prolonged ring, resulting in a very natural acoustic sounding tone.The circuit was specifically tailored for this purpose and does not give the same result as just using a decay envelope with the regular CV input. Experimenting with different trigger voltage and length will affect the response of the decay and overall shape. It will also work with other control voltages but will add a falling slew to the signal. Trigger the CV as well as the Klang input at different intervals for simulating the impression of striking a drum or string instrument in different ways.
Finally, the input is AC coupled and has a dedicated attenuator with clipping overdrive towards the end of the pot range for adding a bit of extra bite to the incoming signal. The signal input is scaled for 10Vpp audio signals. The AC coupling comes after the overdrive circuit so you can add offsets to your audio with RYO Ampmix and many other modules to get an asymmetric clipping.
more here: ryo aperture