Fundraiser: Mutable Instruments Streams for VCV Rack

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.



Streams can function as a signal enveloper, vactrol, envelope follower, compressor, and more. Details at


can someone give me an ex[explanation about what a Vactrol is and it application?

edited I m not sure what is happening using paypal


any clue?

same error here, can’t use paypal :frowning:

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

Here’s an 8-channel vactrol-based switched VCA/LPG that a friend made for me earlier this year:

Mutable Instruments Streams can emulate a vactrol in one of its modes (see its manual).

Email with a full screenshot of the page where you see that error message.

6 Likes has a good list of the generally available vactrol parts and their performance characteristics:

I’m rather partial to 1, 4, and 9 myself.

1 Like

paypal worked now, thanks, whatever it was. :slight_smile:

is a cleaver implementation for a bulb, thanks for your clear explanation also , the page is working now!

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! 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.


This project has met its funding goal! Thanks to everyone who donated, especially to whoever finished the goal with a $100+ donation.

I will ship my Streams to Alright Devices tomorrow, who will get started on modeling the analog VCFA circuit and porting the microcontroller firmware.


Thanks so much everyone for the support! I’m excited to get started on this one.


any news about the developement?

or maybe an ETA?

1 Like

Last week he said he said he’ll send me something soon. Then I’ll need to review, test, and release which may take a few days.


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.