---------------------------- Original Message ---------------------------- Subject: Re: [music-dsp] Antialiased OSC From: "Phil Burk" <philb...@mobileer.com> Date: Tue, August 7, 2018 12:59 am To: "robert bristow-johnson" <r...@audioimagination.com> "A discussion list for music-related DSP" <music-dsp@music.columbia.edu> -------------------------------------------------------------------------- > On Sun, Aug 5, 2018 at 4:27 PM, robert bristow-johnson < > r...@audioimagination.com> wrote: > > i, personally, would rather see a consistent method used throughout the >> MIDI keyboard range; high notes or low. it's hard to gracefully transition >> from one method to a totally different method while the note sweeps. like >> what if portamento is turned on? the only way to clicklessly jump from >> wavetable to a "naive" sawtooth would be to crossfade. but crossfading to >> a wavetable richer in harmonics is already built in. > > > Yes. I crossfade between two adjacent wavetables. It is just at the bottom > that I switch to the "naive sawtooth". I want to be able to sweep the > frequency through zero to negative frequency. okay, i get it.� if DC wasn't the bottom, but some octave on the keyboard, it would be a saw with sample values very close to the "naive sawtooth" ramp but could still have some limit to harmonics. > So I need a signal near zero. > But as I get closer to zero I need an infinite number of octaves. yup. > So the�region near zero has to be handled differently anyway. > > >> and what if the "classic" waveform wasn't a saw but something else? more >> general? > > I only use the MultiTable for the Sawtooth. Then I generate Square and > Pulse from two Sawteeth. yup. that works.� detune them slightly and it sounds like a monster analog synth. > <https://lists.columbia.edu/mailman/listinfo/music-dsp> > Also note that for the octave between Nyquist and Nyquist/2 that I use a > table with a pure sine wave. If I added a harmonic in that range then it > would be above the Nyquist. that i would expect.� pretty high octave. the octave below that would have a sine and it's octave up.� the octave below that would have the sine (at the fundamental) and three harmonics above it... � -- r b-j� � � � � � � � � � � � �r...@audioimagination.com "Imagination is more important than knowledge." � � � �
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