square PW

Aug 3, 2006 at 1:25pm

square PW

Hello,

i’m using a “complete” wavetable sound file in a 2d.wave~ as an
oscillator : having a beautiful squared wave shape selected, how do i
simulate the classic analog “pulse width” on this one ?? In better
words, how do i manipulate the signal as if i was changing the pulse
width in a generator ?

thanks in advance

f.e

f.e chanfrault | aka | personal computer music
> >>>>>> http://www.personal-computer-music.com
> >>>>>> |sublime music for a desperate people|

#27026
Aug 3, 2006 at 5:15pm

On 8/3/06, f.e

wrote:
>
>
> i’m using a “complete” wavetable sound file in a 2d.wave~ as an
> oscillator : having a beautiful squared wave shape selected, how do i
> simulate the classic analog “pulse width” on this one ?? In better
> words, how do i manipulate the signal as if i was changing the pulse
> width in a generator ?
>
> I’m not completely sure but I think this isn’t going to sound nice with
just one waveform. You can use multiple samples at different pulsewidth
settings and interpolate between them. This is probably the best solution
anyway if you want to make it sound like analog.

Using just one waveform you could play it back faster and silence the
remaining cycle time to narrow the pulsewidth.

-thijs

#81396
Aug 4, 2006 at 4:31am

you could skip samples too, although i dont know if that is ok for your particular use. the msp tutorials give a simple algorithm for making a pulsewave w/o samples: you use a phasor, and compare its output to the pulsewidth desired (in the range 0 to 1). if positive, send a 1, if negative, send a -1.

#81397
Aug 4, 2006 at 8:26am

This could be a good idea, but how do i feed a buffer~ with a square
wave containing all the different pulsewidth settings ?
Also found this :
http://www.soundonsound.com/sos/Mar03/articles/synthsecrets47.asp
Interesting but not really helpfull…

Nevertheless, does anyone succeed creating a nice sounding PWM with 2 tri~ ?

f.e

f.e chanfrault | aka | personal computer music
> >>>>>> http://www.personal-computer-music.com
> >>>>>> |sublime music for a desperate people|

Thijs Koerselman wrote:
>
> On 8/3/06, *f.e*

> > wrote:
>
>
> i’m using a “complete” wavetable sound file in a 2d.wave~ as an
> oscillator : having a beautiful squared wave shape selected, how do i
> simulate the classic analog “pulse width” on this one ?? In better
> words, how do i manipulate the signal as if i was changing the pulse
> width in a generator ?
>
> I’m not completely sure but I think this isn’t going to sound nice
> with just one waveform. You can use multiple samples at different
> pulsewidth settings and interpolate between them. This is probably the
> best solution anyway if you want to make it sound like analog.
>
> Using just one waveform you could play it back faster and silence the
> remaining cycle time to narrow the pulsewidth.
>
> -thijs

#81398
Aug 4, 2006 at 9:28am

I remember reading this and building something based
on it – I can’t remember what came out of it, and I’m
currently suffering that interminable wait for a dying
hard drive to clone (wish me luck…), so I can’t
check it right now.
Out of curiosity, isn’t the ‘buttery goodness’ of the
more recent square/pulse wave object (can’t even check
the damn thing’s name) ‘analogue’ enough for you ?
cheers
Roger

> Also found this :
>
http://www.soundonsound.com/sos/Mar03/articles/synthsecrets47.asp
> Interesting but not really helpfull…
>
> Nevertheless, does anyone succeed creating a nice
> sounding PWM with 2 tri~ ?
>
> f.e
>

#81399
Aug 4, 2006 at 4:00pm

I’ve never done it myself, but I think you can simply crossfade 2 different
wavetables at a time. If you have an array of buffers, you can mix them for
the in-between settings. Afaik the same technique is also used to spread
multiple waveforms across the keyboard. Interpolating between different
spectrums for low and high tones. In a sense interpolating the spectrum is
the same thing as changing the pulse width.

Of course using the anti-aliased oscillators in max will be a lot less
troublesome. Like Roger said, I don’t know how “analog” you want the thing
to sound.

-thijs

On 8/4/06, f.e

wrote:
>
> This could be a good idea, but how do i feed a buffer~ with a square
> wave containing all the different pulsewidth settings ?
> Also found this :
> http://www.soundonsound.com/sos/Mar03/articles/synthsecrets47.asp
> Interesting but not really helpfull…
>
> Nevertheless, does anyone succeed creating a nice sounding PWM with 2 tri~
> ?
>
> f.e
>
> f.e chanfrault | aka | personal computer music
> > >>>>>> http://www.personal-computer-music.com
> > >>>>>> |sublime music for a desperate people|
>
>
>

#81400
Aug 14, 2006 at 8:49am

f.e wrote:
> Nevertheless, does anyone succeed creating a nice sounding PWM with 2
> tri~ ?

I don’t understand the whole thread, doesn’t rect~ give all you need?
In the help file is an example for a normal and an antialiased PW
oscillator….

Stefan


Stefan Tiedje————x——-
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#81401

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