---------------------------- 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.
> 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 

> <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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