Do you really need TWO VCAs?

[jukingeo]

Hello all,

I had this question that had been bugging me since I first found the MFOS website and was browsing through all the modules and other projects on the site.

One thing that caught my curiosity was the module that has two VCAs. I also noticed that this is repeated on the Synth Experimenters board.

Now, while I am far from an expert in creating sounds on a synth, I have been exposed to them in the past. I have also repaired some vintage synths. Generally I have seen synths with two or even more VCO's and LFO's. On the rare occasion I have seen synths with two VCF's. However, I never came across a vintage synth that had two VCA's. The ARP 2600 was one of the larger synths I worked on and it too only had one VCA.

I generally accepted the VCA as the last stage in which you could control the volume using a envelope generator, or LFO. So outside of doing some strange pseudo stereo panning effects, I can't see why one would need more than one VCA in a synth.

If indeed there is a great advantage to having two VCA's I would like to know what they would be.

Thank You,

Geo

[Skrog Productions]

Hi again

There are many uses for 2nd , 3rd 4 and more vcas when patching sounds, have a look at ray's delayed modulation project for one use of a second vca , patching a 2nd vca - controled by an envelope, like his circuit, gives an lfo modulation a slow or fast fade in effect.
Also a handy pre-amp for a thin highpass or bandpass filtered sound.
And lots of other permutations for crazy sounds.


Dave.

[PHOBoS]

ah there's dave, somehow I expected you to reply
yeah 2 VCA"s isn't that much, I've noticed that when patching I first leave out the VCA's and then look for places where adjusting the CV level
has a nice effect. I then wire these signals through a VCA. (So I often use them for CV's instead of audio signals)

[Cynosure]

This is for a modular system where any configuration is possible. you are only thinking of a standard pre configured synth.

Here are some examples of vca use within the circuit instead of just at the end:

-Vca with an envelope to modulate lfo signal so the amount of lfo modulation changes over time The is useful to make vibrato that slowly gains in intensity. Some synths actually have this built in but it isnt labelled as a vca so it isnt obvious.

-FM synthesis. Using a vca and evelope to create a modulator similar to above but starting open and fading out.

-Adding noise to percussive sounds. Things like kick drums often have more punch with a little burst of noise.

-KS synthesis using a vca to add a noise or sound burst.

These are just some common examples but with a modular the possibilites are endless.

[jukingeo]