[PD] Help - filters & band limited oscillators!

[Roman Haefeli]

hello again

i improved guenter's bandlimited square a bit. i noticed that it is
hardcoded to 48kHz and accidently i was running pd at 48kHz, that's why
it sounded quite good here. however, how far i can see it, the part,
that selects the appropriate table, is not working as it should. i
couldn't completely follow, how it works, but it seems to switch only
correct from tab1 to tab2. for other tabs it switches at too high
frequencies, which might introduce a bit aliasing. 
in my version the tables are generated on loadbang, which makes the file
much smaller and easier to adapt for other waveforms. the tabselector is
now dependent on the sampling rate, so it should sound well at different
rates now.  in order to provide the full spectrum even in low
frequencies, i added a raw square generator. below a certain frequency,
the oscillator switches to the raw square version, so that it should
sound good at arbitrary low frequencies. the number of tables generated
on loadbang can be changed. a bigger value lowers the frequency, at
which the oscillator switches to the raw version and vice versa.

i hope you'll have fun with it.

roman
  

On Wed, 2007-03-14 at 04:46 -0600, David Powers wrote:
> I found those, but are they really band-limited? I'm fairly sure I
> hear ugly digital artifacts in the saw. The square appears to be
> broken, unless I made a mistake cutting and pasting those 1500 lines
> of code into my text editor (kinda hard to tell).
> 
> It's 5 30 am here and I've not slept yet :-(
> 
> I can't believe there's STILL no readily available
> external/abstraction for such a common synthesis task, I just want a
> "nice sounding" example that will compare with the VST's which I will
> be hosting from within PD; right now "ASynth" sounds about 100x better
> than anything made in PD itself ...
> 
> Oh and I don't see any "J" example PD patches, my PD patches don't go
> that high.
> 
>  ~David
> 
> On 3/14/07, Roman Haefeli <reduzierer at yahoo.de> wrote:
> > hello david
> >
> > i found examples for a bandlimited saw and bandlimited square by g.
> > geiger in the archives. might this is what you are looking for.
> >
> > http://lists.puredata.info/pipermail/pd-list/2006-05/038681.html
> >
> > cheers
> > roman
> >
> > On Wed, 2007-03-14 at 03:05 -0600, David Powers wrote:
> > > Hello everyone,
> > >
> > > I tried google and it was no help, and the server for the list archive
> > > seems to be down temporarily.
> > >
> > > Anyway, I'm giving a free (as in free beer) workshop in Chicago in
> > > about 16 hours, on the basics of digital synthesis. I have decided to
> > > use Pure Data to give my presentation, and use mostly non-commercial
> > > software.
> > >
> > > However, I'm still missing the following for demonstrating "proper"
> > > subtractive synthesis:
> > > 1. Good, out of the box "analog-sounding" filters. I'm using [moog~]
> > > right now, but I'm not all that satisfied with the sound compared to
> > > the filters in my favorite VST's ...
> > > 2. Band-limited square and sawtooth waveforms.
> > >
> > > For teaching purposes PD is great, and ideal for my demonstrations.
> > > But as it is, I'm having to use VST's within PD in order to
> > > demonstrate a "nice sounding" synth. It would be nice to show that PD
> > > can do it without using stuff built in Steinberg's format. That would
> > > also let the Mac people replicate my work, if they are interested.
> > > Note, nobody in the workshop has ever tried Linux, except me, so Linux
> > > plugins are not helpful in this case.
> > >
> > > I will post my patches after I give the workshop, though they are
> > > nothing fancy ... just basic:
> > > sequencer - oscillator - vca - filter. Good for demoing though, I'm
> > > starting with additive first, then subtractive.
> > >
> > > ~David
> > >
> > > _______________________________________________
> > > PD-list at iem.at mailing list
> > > UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
> >
> >
> >
> >
> >
> >
> > ___________________________________________________________
> > Der frühe Vogel fängt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail: http://mail.yahoo.de
> >
> >
> 
> _______________________________________________
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