Envelope control voltage

Is there any way to output an envelope control voltage? If I connected the ‘Power’ module directly to the ‘Envelope’ and used an external trigger, for example ‘Button’, to gate the ‘Envelope’ would the internal VCA output an envelope shaped control voltage? I’m assuming that the centre pin of the ‘Power’ module outputs a fixed voltage, which could then be shaped by the triggered ‘Envelope’ and it’s internally linked VCA.

I suppose I should just have asked if the VCA in the ‘Envelope’ module is DC Coupled :wink:


@rcf1956 We gave this a test in house, and had some of our smartest people on the task and could not get it to work in the way you described. Perhaps this request would be the sort of thing to look to the bitLab to create? We always enjoy your feedback and suggestions!

Thanks for answering this. An envelope control voltage is a pretty basic modulation source in analogue synthesis terms; it would be good to have a dedicated fully fledged envelope shaper with cv output.

Edit: One of the very helpful guys, DJFonzi, on the Muff Wiggler forums ‘littleBits’ thread has demonstrated that this does in fact work. He gave me permission to link to his post on here:


He used a split from the power>envelope>filter freq; the only difference between his patch and my suggested version is that he used the sequencer to gate the envelope trigger, whereas I used a button. In his example, the filter frequency is definitely being modulated by a control voltage which can only be coming from the envelope output. This suggests that the internal VCA of the envelope can shape control voltages as well as audio signals?

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I’d really be interested in knowing what your folks were trying, Patrick.

I don’t think the system power (VCC) is actually going through the VCA per se. I think the EG is just spitting out the same voltage that drives its built-in VCA as its “signal.” I imagine if you measure the power input voltage on the bitsnap, and the output voltage on the other bitsnap, they’ll always be the same, regardless of how you set the EG. I haven’t looked at the schematics, but this is what would make sense, and really, it’s the only way it COULD be working, otherwise anything downstream of the EG (when working as a VCA) is not going to be getting its expected 5V. Like the speaker, for instance.

I think I see what you mean; are you suggesting that the Envelope possibly outputs it’s internal cv by default, when it isn’t receiving any audio (to the internal VCA) on it’s input bitsnap?

Yeah, that’s kind of my assumption, although when you put it that way, it sounds like it’s smarter than it probably is. Let me go look at the files on github and see if I can make sense of it.

Of course the ‘Button’ bitsnap output triggering or gating the ‘Envelope’ in my original example, would only work if the ‘Button’ was also receiving a signal on it’s input (male) bitsnap …otherwise it has no signal/voltage to switch.

Sorry for digging up this old topic, but it showed up when i was googling about for the answer to something i have noticed about the envelope bit: it outputs a click every time it is triggered externally while there is also an audio signal passing through it. Now, if i understand correctly after reading through this thread, the envelope outputs a signal regardless of anything being on arriving at its signal input when triggered via its trigger input, is this the source of the click? It’s a quite prominent and annoying sound to have sometimes.