1). With a patch from scratch, two important design decisions are the starting waveform and filter choices. In theory, the Cutoff frequency is where the filter chops off the waveform. The reality is that it slopes off at a given rate. A
Low
Pass
4-pole (24dB/octave) slope is one very common filter type (Moog). So is a LP-2 filter (12 dB/Octave - Oberheim). I initially thought that the muted example sound would work best with a more gradual slope. It turns out that the Cut 1 LFO modulation and Mod Matrix reacted better with a steeper filter slope.
2). I tend to do my synth programming in a standalone or micro-host. Free from context, outside influences, and potential problems. The presets always get tested, tweaked, & utilized in a DAW, but don't start out that way. Tempo / BPM will give the same results no matter what. But a preset like this is based heavily on sync-to-tempo.
In Rapture, there's an Options button (2nd icon of 4 to the left of the RAPTURE logo). In there, you can defeat the lock to outside MIDI Clock tempo, and use an internal generated tempo. In most cases, you wouldn't want to use this. But in a standalone situation, it comes in handy.
If it sounds right to you, then you're where you want to be. When I used StepGen Retriggers, the AMP envelope triggers were set up on every other step. The steps following each retrigger tended to sound like 'rests'. So I doubled the tempo for programming (description) simplicity. In hindsight, I should've just stuck with 80 BPM, the same AMP Step Generator description, change SYNC setting and number of steps, etc. Whatever it took, as opposed to 'the easiest way'.
3). The first method for the AMG EG was the correct one. That was a bad analogy on my part. You want to go top-left (near-instant attack) to bottom-right (silence). The Sync parameter uses the entire default AMP EG display as its Sync 'increment' (1/2 of a quarter note 'beat' = 1/8 note).
As for the "two (additional) nodes)" ... When you first open up Rapture, you'll see a default node in the bottom-left of every EG display. It can be moved in level (up & down), but not time (left-to-right). It comes in handy when you don't (or you do) want an instant high-level start to your envelope. Your MIDI Note instantly triggers the envelope. In many cases, an instant level change like that can lead to a "pop" (psychoacoustic, or otherwise). All it takes is about a fractional millisecond delay to avoid that.
"Two (additional) nodes" meant to
not count that default node as one of them. It's easier to just right-click in two spots, create your envelope, and have that default node there for later on. If you find yourself with a pesky little popping sound (often the culprit is an AMP EG or CUT1 / CUT2 filter EG), all you have to do is nudge your first right-clicked node slightly to the right.
4). Sync vs. Freq. If you dial any Sync parameter beyond 1/8T or 128, the Sync control goes to OFF, and the Freq control becomes active. [The fastest way is to left-click + right-click on the Sync parameter.] You're no longer synchronized to tempo. The speed/rate is now frequency in Hertz. (cycles per second). When you hit a MIDI Note, the cycle starts. If you look at a default LFO display, you're seeing two LFO cycles displayed (somewhat counterintuitively).
The only point that I was making there is there is an equivalent rate in Frequency / Hz. to whatever BPM / Sync rate you're using. [Google BPM to Frequency Calculator or charts.]. Sometimes, you want the MIDI Clock tempo to keep your synchronization timing for you. Other times, you'll want to have your chords trigger the start of a sequence, envelope or LFO cycle, and have the speed of the events determined by a predictable rate.
5). The Cut1 LFO modulates the Cutoff frequency of Filter 1. (The same scenario and layout goes for Filter 2.) In this example, you set an initial frequency point for the LP4 filter to drop off using the left-most CUTOFF knob. I had you center the control at about a 12 0'clock position. Mine happened to be set to 500.8 Hz., but it just had to be close to that.
The Cut1
Low
Frequency
Oscillator starts at this initial frequency [500.8 Hz.], and brings it
above and
below it. The Sync or Freq determines the speed that it modulates. The Depth determines how far up & down it deviates from that initial frequency. Look at the Sine shape in the graph. It starts at the midpoint [initial Cutoff knob position], goes above it, down through midpoint again, below it, then back to the initial Cutoff knob position. [Twice over, because 2 complete cycles are represented in the graph.]
I had you set the Depth control there to 1200 cents (one octave). But the LFO is a bipolar modulator (above and below the initial Cutoff position). I steered you wrong with 600 cents up and 600 cents down. Apparently, I was calculatiing that the Depth was halved for each of the directions. But that just sounds like a brain-fart that slipped through from the "speed programming" exercise.
I just tested a similar scenario using Pitch and Pan LFOs, Full Depth Up, and Full Depth down. So the effective Depth total excusion [up + down] is doubled, not halved. You can test it yourself:
Pitch LFODisplay: Pulse/Square 3
Status: On
Depth: 100
The rest at defaults.
Play any MIDI Note. It sounds like a WWII Euro ambulance (without the Doppler effect). One semitone [100 cents] up, and one semitone [100 cents] down. Now, turn the Status to Off. You have the original played note smack in the middle.