Mountain Coast because an Appalachian (myself) designed the patch with some West Coast/Buchla ideas. Mountain coast features pseudo-lowpass gates with logarithmic envelopes, FM oscillators, per voice control over oscillator duty cycle, FM ratio, and LFO rates (on the MIDI version), accompanied by an analog-style delay to create all sorts of plucky, unexpected rhythms and timbres.
I designed the patch around plucked, LPG sounds, but I gave it more breadth than this, with attacks capable of short swells, limited resonance control over the filter, and an optional sustain stage on the MIDI version.
It functions as a four voice synth, but you could think of the voices as being capable of some (minor) independence, as well — each voice can have its own timbre, due to individually assignable oscillator duty cycles and FM ratios (or you can push a button and control all the voices at once); the MIDI version of the patch also includes individual LFO rates for the LFO controlling the FM amount on each voice. The effect is sort of like using multiple synths to create polyphony, as is sometimes achieved via round robin-ing over MIDI or CV. The outcome can be quite melodious, or it can be jarring and discordant (largely dependent on the FM ratios employed). This approach really comes alive when you apply a sequencer or arpeggiator to the patch, especially if it repeats in intervals different from four (e.g. a three-note arpeggio or a seven note sequence).
There are two versions in the zipped folder: MIDI and CV, reflecting different control mechanisms.
In the MIDI version, the MIDI channel is defaulted to channel 1. You can change the channel by finding the MIDI note in module on the page labeled “MIDI.”
In the CV version, three of the CV inputs are used, labeled: Pitch, Trigger In, and Velocity. Pitch and Trigger In work as you likely expect (the patch also accepts gates but it converts them to triggers internally; there is no sustain available on the envelopes in the CV version). Velocity accepts any 0 to 5V source (or other sources, if you want to change the input module). If your sequencer or controller doesn’t produce velocity, the patch can also generate a value for this input if you press the “Generate Velo” button in the bottom left corner. It does need some sort of velocity input to function appropriately, as the intensity of the LPGs are tied to velocity.
Controls:
In the top left corner are the controls for the envelope. “Attack” ranges from non-existent to longer logarithmic swells. “Decay” can go _quite_ long, but covers everything from quick plinks to longer plucks and even longer slowly fading sounds. On the MIDI version, a “Sustain” stage can be introduced (the envelope is then, more accurately, an ASR envelope, rather than an AD envelope).
Below this are controls for the FM amount. “FM amount” sets a base level for feeding the carrier to the modulator. “FM amt env depth” and “FM amt LFO depth” can then be used (positively or negatively) to add or subtract from this amount.
On the next row are controls for the LPGs. “Intensity” determines the overall amount the LPGs can open. If you want a softer sound, set the intensity lower; for a brighter sound, keep it at 1.000. “Resonance” sets the resonance of the filters used to create the lowpass gates; it is restricted from going too high, but adds some nice variety to the sound in the range it is limited to.
The “High pass filter frequency” serves two purposes: One, it shapes the tone of the low-end, allowing you to lift some of the “mud” away and tighten the transients. Two, it determines how much the LPGs “bleed.” (I intentionally used this feature, heard on some LPGs, a byproduct of the filters not entirely returning to ground. In such cases, a small amount of sound would always be heard from the oscillators. I tried it and liked it, although I can understand how it would annoy others. If you want to utilize a similar design, I’ll explain how to eliminate bleed when I get an entry up on this LPG design on Tips and Tricks in the next day or so.)
The delay is designed to emulate (in part) an analog delay, with increasingly darker repeats. This sound I think really complements the patch, because the sharper transients are mellowed out with each repeat. The “Delay level” determines how much signal is sent to the delay signal path. The delay is on a send, so it adds to the overall volume (just something to be aware of). “Delay time” ranges from .02 ms to 2 seconds, and that range allows the delay to be used for echoes and pseudo-reverbs but also modulation effects like chorusing and flanging. “Feedback” determines the amount of regeneration. “Mod depth” and “rate” are used to dial in the sine wave modulation of the delay line.
On the right side are where things get really interesting:
In the MIDI version there are three controls that can be assigned on a per-voice basis; in the CV version there are two. In all cases, the controls work like this: if the button at the top of the row is off, each voice is controlled individually, by the value modules in the column. If the button is on, only the top value module in that column controls all the voices. So, you can either tailor each individual voice, or control them en masse. The inspiration for this patch was some of my generative patches, and in those, I like to have similar voices with subtle differences, so the outcome is more unexpected and surprising; I tried to think of a way to apply that to a polyphonic, controllable patch without it becoming, you know, impossible to dial in, and this was the compromise I came up with.
“LFO rate” controls the rate of the LFO modulating the FM amount.
“Duty cycle” controls the duty cycle of the sine wave carrier oscillators. Changing this is a bit like wavefolding — higher duty cycles have more harmonic content from the distortion of the sine wave.
“FM ratio” determines the relationship between the modulator’s frequency and the carrier’s frequency. Values like “E1” (+a fifth) or “A2” (+2 octaves) will have generally harmonious outcomes, while other ratios (e.g. .0783) that fall out of a harmonic sequence, will have more dissonant outcomes. This is where you can really shape the per-voice timbre the most.
