[sdiy] RE: Polyphonic synthesizer (controlling with vactrols)

[Paul Maddox]

Andre,

>For waveforms such as sawtooth, square and triangle, software
>oscillators are hard. If the frequency is not a whole
>submultiple of the sample rate, aliasing occurs. Unless you
>generate the wave form additively, and that can be quite costly
>in terms of CPU for low fundamental frequencies (at 50 Hz, there
>are 400 harmonics).

not so...
use Phase accumulator oscillators and a simple waveform lookup..
Listen to the Monowave (http://www.Modulus.wavesynth.com/monowave/)
It uses two phase accumulator oscillators and an eprom with waveforms in.
No aliasing there, unless you press the de-rez button :-)

in short, use variable sample rate playback for raw waveforms, its sound
much nicer..
Those that didnt include most of the EMU range, and even the DW6000/8000
used fixed sample rate.
They started off with 1024 byte waveform samples, massive!!!

Paul
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