I've been asked a few times now why you need a VCA along with an ADSR or other envelope generator and it made me realize that people might not know how those two pieces work together, so I thought I'd tackle that in a patching video.
"Audio valve"? This immediately reminded me of remote cut-off pentodes, where transconductance (and gain) varies a lot with control grid bias voltage. These tubes were used in RF circuits for automatic gain control to increase the signal from weak radio stations while not letting the strong ones overdrive the demodulator and audio frequency amplifier. Basically, a dynamics compressor, but for radio frequencies.
Thanks for this. I appreciate your comment that some of these things are just "assumed knowledge". It's these really fundamental things that are often missed. So many videos talk about what a module can do without showing a clear and basic patch. Super helpful!
Days. Multiple days I have searched for an explanation of the ADSR/VCA relationship that made sense to me. Great stuff. Thank you. Now, as the other guy said, off to buy more stuff.
Very clear explanation. I have some questions. 1. What parametes does the keyboard of a synthesizer change? The frequency of the oscilator? The voltage rhat controls the VCO? 2. If there is only one oscilator to generate que frequency, how does the system works to generate chords? 3. How many "channels" are there on the sequencer and what parameter does the sequencer change? The voltage control to be aplied on the modules? Thank you!
Hey, thanks, I'm glad it was helpful. To answer your questions: 1) It's both. Playing a note is going to send a different control voltage to the oscillator, and that will determine the frequency of the output. In eurorack, adding 1 volt to the CV increases the pitch by an octave (which is a doubling in frequency) 2) In short: you don't. Many eurorack systems are monophonic - they just have the once voice. There are a number of modules that will output chords, but if you want to do proper polyphony then you will end up needing one full oscillator-filter-adsr-vca set for each note in the chord. I have a video that demonstrates that setup: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5DMUukOaqKE.html 3) Sequencers can be quite different, but this one has 8 steps and it outputs 3 CVs (they're based on the same knob settings, just scaled, but that can still be pretty cool). In this case it is doing the job of the keyboard, sending the CV to the VCO to tell it what pitch to play, but of course it can control anything. One thing I like to do with this one is to use one output for the pitch, and another one scaled down to change the filter cutoff. That way you get a subtle difference to how the notes sound at different pitches.
Very useful, thanks - now if you could just make a video that demystifies the Three Sisters in a similarly concise and informative way next, that would be awesome...!
Hey, thanks. Well, I even have a Three Sisters here! More than anything, I'm not sure how to make all the diagrams I'd want. :) I'm doing Clouds and the Triple Sloths next, maybe I'll have a plan after that.
Thanks! Glad it was helpful. I've never used a Maths as a VCA, but apparently it can be used that way 'in a pinch' (so it probably isn't super clean and reliable) and it requires all 4 channels, but, from the website: Patch audio signal to CH. 1, with RISE and FALL at full CCW, or cycle CH. 1 at audio rate. Take output from SUM out. Set initial level with CH. 1 panel control. Set CH. 2 panel control full CW to generate a 10v offset. Audio will start to clip and may become silent. If it's still audible, apply an additional positive offset with CH. 3 panel control until it is just silent. Set CH. 4 panel control to full CCW and apply envelope to Signal IN, or generate envelope with CH. 4. This patch creates a VCA with assymetrical clipping in the waveform. It will work with CV also, but be sure to adjust CV input settings to deal with the large base offset. The INV output may be more useful in some situations. Honestly I think you'd have a way better time investing in something like a 2hp dual VCA.
thanks. I was using the adsr and oscilator alone but I kept wondering "why won't this stop playing?" VCA's are your friend. P.S. Your audio is really quiet.
