Help bring Mutable Instruments Streams to VCV Rack, a 2-channel dynamics processor with an analog VCF/VCA and a digital brain. Watch DivKid’s video for a quick demo. Fundraiser starts today until Sept 27.
A vactrol is quite literally an LED or incandescent light bulb inside a closed space with a photoresistor.
When a signal (such as a gate) is passed through the light bulb, it begins to illuminate over a millisecond or so, causing the photoresistor to decrease its resistance to e.g. “open up” an envelope. When the signal (gate) stops, the light takes several milliseconds to “die down” to darkness, making the resistance gradually increase back to infinity. This results in an inexact, gradual envelope that can be combined with a VCA/LPG circuit to make musical, Buchla-y “plucks”.
Here’s an example of a DIY vactrol built from standard parts. (Source DIY Vactrol)
Here’s an 8-channel vactrol-based switched VCA/LPG that a friend made for me earlier this year:
Vactrols are essentially great for combining a VCA with a low pass, meaning you use less modules (eg. Makenoise Optomix). Alongside the Buchla “plucks”, I find they’re useful in percussion sounds (conga slaps, FM patches…) and with hardware YMMV with trigger or gate duration, this can impact on how it responds.
Less than $200 more to go on https://vcvrack.com/fundraiser! Funding this project supports the free/open-source Audible Instruments plugin which, if this fundraiser is successful, will bring it one step closer to a complete port of all Mutable Instruments modules. Grids, Edges, Peaks, and maybe Yarns will be all that’s left, and I don’t anticipate a fundraiser being needed for those.
The engine of Dual Dynamics Gate is finished. Before releasing, a bit of bug fixing, more A/B testing against hardware, and code review is needed. This is a very exciting module to have in VCV Rack.