Started 4 years ago (2015-01-31T14:00:00Z).
Ended 3 years ago (2015-03-01T14:00:00Z).
This is a subgoal of my audio-toy project Ampliscape. I want to make a lot of preset synthesizer content and the easiest way to ensure it gets done is to make it an everyday task for the month of February. You are welcome to join in if you have sound design goals of your own.
A simple waveshaped triangle patch inspired by, although not quite resembling, the interstitial music of the early episodes of "The Computer Chronicles." In the 80's, arpeggiation of these kinds of basic synth sounds was a typical "scientific" or "high tech" music bed.
This is the last patch I'm doing for this streak! It turned out to be very productive.
It's a detuned sawtooth patch, but it's also a pulse width modulation patch. At first I thought I would have to add an inverted sawtooth oscillator or negative gain to pull off this classic trick, but then I realized that I could do the inversion with the waveshaper. I felt very clever when I did that, and then I added some modulation to the waveshape at attack time so that you get a blast of sawtooth followed by the PWM timbre.
I improved the patch editor so that I could hold the shift key for fine tune adjustments. This helped me set the pitch LFO on this patch to 12.001 semitones(it still wasn't quite fine enough I guess). It's a sine wave but I waveshape the attack so that it's more squarish-beeper like and then filters out to make a cleaner echo.
I was feeling low about this synth yesterday, but today I come back with this sound which invokes a bit of that "Atari 8-bit" feel by using the tonal noise oscillator where it really shines - gritty bass sounds. I layer it with a sawtooth to distinguish the high end and fill it out.
I aimed for something like a DX7 sound by waveshaping one part against a sine and filtering it to get the "tine," and then leaving the other part a simple sine. It's playable, however it sounds nothing like the famous "DX7 Rhodes", it's harsher and it aliases more readily.
This is an original patch which actually uses the highpass filter(unlike almost every other sound I've done which uses LP or BP). The goal was to make something that gets the smooth character of gradually enveloped sines, but with a definite high end buzz, which is provided by a sawtooth as usual. Playable, but not quite what I had hoped for.
It's the "Jump!" sound, and it's accurate enough to start phasing against the original recording. I didn't play the actual riff, the keyboard doesn't have the range to do the correct voicing to begin with, but I do play some notes around the appropriate octaves and chords. For examples of the sound: http://www.synthtopia.com/content/2009/06/30/van-halen-jump-demo-oberheim-obx-a/
Sawtooth, downpitched, resonant low-pass envelope. Waveshaped for added punch. Demo is the Good Times riff roughly as interpolated in Rapper's Delight. I took some time and used a click track to actually get the rhythm almost acceptable but not really(ha, foiled by latency again).
Over the past few days I've been improving oscillator and filter quality. Yesterday I improved the pulse waves by doing the correct form of additive synthesis on the rectangular function(instead of taking a square wave and awkwardly rescaling it). After I did that I looked into improving the tonal noise, which has always had inherent aliasing, being an oscillator based on a small single-cycle noise pattern. I decided, based on my success with oversampling elsewhere, to oversample the tiny initial waveform 4x, making aliasing much less present until you hit C-6 or so. In the process I discovered that I had made the wrong constants for the Blackman-Harris window that I'm using to oversample things, so the filter is a little cleaner now too. I also shrank the tonoise waveform to 32 samples instead of 64. The downside of doing this is that it's more "tone" and less "noise," the upside is that it performs better and it's more straightforward to modulate.
Today I made just about the simplest patch you can make with the tonoise oscillator: envelope the noise in and out. This gives you an approximation of Karplus-Strong style pluck sounds, only more metallic sounding.
This is haaard to synthesize well. I "finished" it, started typing up this post, and then went back and spent another 20 minutes on it. The final thing is two layers of noise, filtered in different ways, both of them using the "fast sawtooth LFO" trick that makes it sound more like multiple impulses. A third layer might make it sound richer, but I stopped there. For a really good example of this style of synth clap see "Being Boiled" on Human League's Travelogue.
I upgraded the synth to use 2x oversampling on the state-variable filter this evening. This means that before the filter runs, the incoming samples from the oscillator are upsampled(for every 1 incoming sample, two are generated). We generate the new samples by convolving the Blackman-Harris window over the old ones. The SVF is run over this double-rate buffer, and the output is subsequently decimated back down to the original rate. The resulting filter is more accurate and smoother-sounding.
The patch I made after doing this modulates cutoff, resonance, and amplitude over a sawtooth - it's perhaps not the most challenging example, but the timbre is very reliant on filter quality, and it hits my soft spot for long, evolving pad sounds.
This is actually a pretty complicated one. I wanted to make something vocal sounding, and it's modulating pitch, cutoff, and resonance on a band-passed sawtooth. Resonance on this filter tends to come out sounding harsh and grainy so I took some time finding ways to keep the settings in a musical range, eventually settling on a "synth meow" timbre.