There’s a lot going on when programming an analog synth. I will quickly go over how to make an ambient synthetic sound which sounds a little like a string sound, because it sounds nice, and because its pretty simple for beginners to set up.
Here’s the sound: https://soundcloud.com/caulixtla/jp-08-slow-sawtooth
Here’s a closeup of how the synth panel looked when making this sound: https://i1.sndcdn.com/artworks-000133052376-qe32ji-t500x500.jpg
First, we have the two VCOs . The VCO determines the general characteristic of a sound. There are a number of waveforms a VCO can have; here both VCOs have a sawtooth wave. You can see that; on the knobs on the right hand below “VCO1” and “VCO2”, both are pointing at the /|/|/|/| looking sawtooth wave.
The sawtooth wave is the waveform to use if you want something that sounds somewhat like a string or horn sound. Whether the sounds is string like or horn like depends on how we change the volume of the note over time — the envelope generator.
OK, so the knobs one to the left of the sawtooth waveform knob determine the tuning of the waveform. On this particular synth, we can only change the octave VCO1 is at (64, 32, 16, 8, 4, 2); when we move the octave selector for VCO1 left or right, it halves or doubles in pitch. 2 is the highest pitch; 64 is the lowest pitch.
With VCO2, we can choose which note the sound is at and fine tune the note. In this sound, VCO2 has the same octave and note number as VCO1, but its fine tuning makes it a little sharp compared to VCO1. Having the two VCOs slightly out of tune of each other results in a “chorusing” effect, where the sound has movement and sounds a lot richer than a single VCO.
After this, the mix knob gives the two VCOs the same volume in order to maximize the intensity of the chorusing effect.
After going through the two VCOs, the sound goes through a high pass filter (HPF), which is sometimes useful for making a sound less muddy. We don’t care about that here, so the HPF is on bypass, letting all frequencies through.
Next, we have the VCF, which is a low-pass filter here. Some synths allow the VCF to be a high-pass or band-pass filter, but this particular synth only allows the VCF to be a low-pass filter, which is the most commonly used filter.
A low pass filter is used here to make the sawtooth waves be less buzzy sounding. We have a fairly low cutoff, and we have the filter set to reduce the volume by 24 db every octave above the cutoff; this is the most common setting used when sculpting an analog sound.
We have both Env mod and key follow set for the low pass filter. Env mod means that an envelope generator will change the low pass filter’s cutoff after we press down a note. Key follow means the note we press will affect the cutoff; otherwise, higher notes will be more muffled than lower notes.
There are two envelope generators in this synth. One envelope generator affects the VCF (low pass filter) cutoff; the other affects how loud the note is over time after we press down a key.
A classic attack-decay-sustain-release envelope generator acts as follows:
- We take attack amount of time to reach the highest possible volume (or filter cutoff).
- We then take decay amount of time to reach the sustain level. Since sustain is at 100% in both envelopes in this example, decay doesn’t do anything.
- We keep the volume and filter cutoff at the sustain level for as long as a key is held down.
- After the note is released, we fade out the sound (and, in this case, lower the filter cutoff) at the speed specified for the “release” part of the envelope. The higher the release value, the longer the note lingers after we are no longer holding down the note.
With this sound, the envelope generator on the left determines how the filter cutoff changes over time after we press the note. We have a really slow attack; it takes a bit of time for the sound to “open up”. We also have a slow decay, but this doesn’t affect the sound, because sustain is at 100%. After we let go of the note, the release is fairly long, resulting in the sound slowly losing higher pitched harmonics.
The VCA (voltage controlled amplifier — how loud the note is) envelope is similar, but with a somewhat faster attack. The reason the VCF attack is slower than the VCA attack here is because this allows one to hear the filter opening up, which gives the sound more movement. The rest of the two envelops are roughly the same.
There is some other features the synth has: Something called a LFO, a number of non-Sawtoothe waveforms, something called “filter resonance” — all of which affect the sound in various ways, but not used in this particular patch (sound). I may go over those in another post on another day.