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Scientifically perfect output has rarely been a primary desideratum of musical instrumentation and in fact is somewhat limiting in terms of the number of timbre

Scientifically perfect output has rarely been a primary desideratum of musical instrumentation and in fact is somewhat limiting in terms of the number of timbres you can create. Ergo why historic analog synths included multiple oscillators per-voice with independent tuning. The early Junos famously included a chorus to thicken up its single DCO per-voice. Later digital Roland synths introduced the "super saw" which is many superimposed detuned oscillators. Going back further, a full orchestra or choir ensemble is certainly not exactly in tune across every performer. And as someone who makes digital synths for a living even 100% accurate fully digital oscillators are difficult to fully realize in practice. Aliasing concerns abound at every stage of a softsynth- there are well-known formulas for calculating alias-free waveforms at a fixed frequency, but these start to get expensive when you also are considering PWM and frequency modulation which are essential tools for achieving a variety of different sounds. And aliasing sounds a lot worse than analog imperfections.

cageface 6y ago
A lot of the best commercial softsynths now support all kinds of audio-rate modulations everywhere in the signal chain. I guess they must just be throwing CPU power at it and oversampling the crap out of everything.
- TheOtherHobbes 6y ago
  Basically - yes. There's now enough CPU to do this. But there's more to that analog sound. The opamps and the rest of the circuitry, including supposedly passive elements like resistors and capacitors, all add tiny amounts of distortion and other parasitic interaction with the rest of the synth which varies with frequency content, level, and dynamics. Human ears are incredibly sensitive to these variations, and the circuits in 70s and 80s synths had a lot of components, all adding their own colour. Which is why if you A/B the hardware with the software, the software rarely wins. In DSP terms there are differences between functional/abstract models, component-level models, and component-level models that include these complications and imperfections. There hasn't been a lot of work done on the latter, and if they were modelled accurately they would likely need an order of magnitude more DSP cycles than current VSTs.
  - cageface 6y ago
    This is true although I find that the current emulations are good enough for a lot of sounds, especially when they’re buried in a mix and played back on a low bit rate stream on bad speakers.
mrob 6y ago
>aliasing sounds a lot worse than analog imperfections The Commodore Amiga has the crudest possible anti-aliasing filter: a single fixed-frequency low-pass filter shared by all 4 channels. It does not work very well, so aliasing is a defining characteristic of the Amiga sound. Aliasing adds high frequency content that compensates for the low sample rates required by memory limitations, and extra harmonic complexity that compensates for the low channel count. I think Amiga modules sound worse if played by something with good anti-aliasing filters.
- nyanpasu64 6y ago
  In my (pedantic) understanding, the Amiga doesn't suffer from aliasing, because it uses a period register used to divide a very high frequency (rather than a frequency register), and always spends an integer number of clocks (output samples) on each input sample. However, it suffers from imaging (a reconstruction artifact) due to using a stair-step (zero-order hold) as a reconstruction filter. And IMO reconstruction artifacts sound worse (not harmonically spaced) when the sampling rate isn't an integer multiple of the note's frequency (the note pitch's period isn't an integer number of samples). Aliasing (a sampling artifact) is an issue in synthesizers which run at low/fixed sampling rates and sample waveforms to produce output (often using frequency registers). This includes modern software synthesis, and also hardware like DS (ZOH, samples, almost like Amiga), N163 (ZOH, short wavetables), Yamaha (FM on sine waves, IDK the details), and to a lesser extent SNES (Gaussian reconstruction, samples). Reconstruction artifacts (extra frequencies at x * fundamental, may exceed sampling rate) are different from sampling/aliasing artifacts (frequencies are taken modulo the sampling rate). But they can combine (like on DS hardware).
- ssalazar 6y ago
  Brian Eno’s quote comes to mind: > Whatever you now find weird, ugly, uncomfortable and nasty about a new medium will surely become its signature. CD distortion, the jitteriness of digital video, the crap sound of 8-bit - all of these will be cherished and emulated as soon as they can be avoided.

cageface 6y ago

A lot of the best commercial softsynths now support all kinds of audio-rate modulations everywhere in the signal chain. I guess they must just be throwing CPU power at it and oversampling the crap out of everything.

TheOtherHobbes 6y ago
Basically - yes. There's now enough CPU to do this. But there's more to that analog sound. The opamps and the rest of the circuitry, including supposedly passive elements like resistors and capacitors, all add tiny amounts of distortion and other parasitic interaction with the rest of the synth which varies with frequency content, level, and dynamics. Human ears are incredibly sensitive to these variations, and the circuits in 70s and 80s synths had a lot of components, all adding their own colour. Which is why if you A/B the hardware with the software, the software rarely wins. In DSP terms there are differences between functional/abstract models, component-level models, and component-level models that include these complications and imperfections. There hasn't been a lot of work done on the latter, and if they were modelled accurately they would likely need an order of magnitude more DSP cycles than current VSTs.
- cageface 6y ago
  This is true although I find that the current emulations are good enough for a lot of sounds, especially when they’re buried in a mix and played back on a low bit rate stream on bad speakers.

mrob 6y ago

>aliasing sounds a lot worse than analog imperfections The Commodore Amiga has the crudest possible anti-aliasing filter: a single fixed-frequency low-pass filter shared by all 4 channels. It does not work very well, so aliasing is a defining characteristic of the Amiga sound. Aliasing adds high frequency content that compensates for the low sample rates required by memory limitations, and extra harmonic complexity that compensates for the low channel count. I think Amiga modules sound worse if played by something with good anti-aliasing filters.

nyanpasu64 6y ago
In my (pedantic) understanding, the Amiga doesn't suffer from aliasing, because it uses a period register used to divide a very high frequency (rather than a frequency register), and always spends an integer number of clocks (output samples) on each input sample. However, it suffers from imaging (a reconstruction artifact) due to using a stair-step (zero-order hold) as a reconstruction filter. And IMO reconstruction artifacts sound worse (not harmonically spaced) when the sampling rate isn't an integer multiple of the note's frequency (the note pitch's period isn't an integer number of samples). Aliasing (a sampling artifact) is an issue in synthesizers which run at low/fixed sampling rates and sample waveforms to produce output (often using frequency registers). This includes modern software synthesis, and also hardware like DS (ZOH, samples, almost like Amiga), N163 (ZOH, short wavetables), Yamaha (FM on sine waves, IDK the details), and to a lesser extent SNES (Gaussian reconstruction, samples). Reconstruction artifacts (extra frequencies at x * fundamental, may exceed sampling rate) are different from sampling/aliasing artifacts (frequencies are taken modulo the sampling rate). But they can combine (like on DS hardware).
ssalazar 6y ago
Brian Eno’s quote comes to mind: > Whatever you now find weird, ugly, uncomfortable and nasty about a new medium will surely become its signature. CD distortion, the jitteriness of digital video, the crap sound of 8-bit - all of these will be cherished and emulated as soon as they can be avoided.