Two questions about the DSM-01's integrated VCA:
(1) Is it a linear or exponential VCA?
(2) Let's say I try to use it as my eurorack synth's only VCA. What limitations would I encounter?
Hi Chysn!
Prefacing my comments with the fact that I have no experience with the module in question- so I'm addressing everything in a general sense.
(1) I don't know the answer, but do know that if you're feeding envelopes into it (which is often the case), those envelopes can also be linear or exponential, etc. So while the 'snappiness' of a sound often relies heavily on an exponential VCA, whether the envelope you are using is linear or not will also affect that.
(2) By a technicality, you can also use an LPF as a VCA. LPG's are also often used as such. Not sure about this, but the slope of the filter might also affect how 'exponential' it sounds as a VCA.
I could have sworn Tuesday Night Machines had a YouTube video on that, but I'm having trouble finding it.
Assuming you understand the limitations of having just one VCA (which are immense), there are still limitations to this particular VCA judging by what's available on the front panel relative to what is available on other VCA modules out there. I'm going to avoid trying to explain the difference with some of the more esoteric VCA's like those that Make Noise offers.
If you look at what Pittsburgh Modular, Intellijel, or Doepfer have to offer, you'll notice that they all have two knobs per channel. One controls the amount of CV-- in other words, it allows you to decide how high the volume will go at the peak/trough of an envelope or LFO. This is something that could be solved with an attenuator though.
The next common feature is a knob that sets how much of the signal is passed through even if the CV is at 0. This is good for tremolo type effects, where you don't typically don't want the signal to ever reach '0'. Of course you can also do that with by splitting the signal and sending the non VCA'd signal and the VCA'd signal to separate channels of a mixer. There are other uses in more complex patches as well.
Another, although less common, feature is the ability to choose whether the VCA is linear or exponential. This is one of the many areas where Intellijel's design shines since it uses a continuous knob for this choice.
Don't get me wrong though, I think the inclusion of a simple VCA on the DSM01 is a genius move and makes it very appealing. Sometimes I wish more modules included simple VCA's on them as it 1. saves space and 2. saves using a VCA on a pedestrian (although vital) function.
Hope you don't mind the long answer and I hope that my ramblings will help you out in some way.