[PD] Pd sounds better than Max?

Andy Farnell padawan12 at obiwannabe.co.uk
Sat Mar 8 03:59:10 CET 2008




There is test I use to evaluate one important aspect of
all synthesis systems. It tests oscillator accuracy.

The patch is by Jean Claude Risset and is an additive concept
he called frequency domain grating, and is analogous to diffraction
grating used in spectroscopy.

Here is Hartmanns paper about it
http://www.pa.msu.edu/acoustics/fdg.pdf

You take as many sines as the system will handle, typically
a thousand or so, and sum them. All must start on exactly the
same phase. Now, if we had a series of _all_ frequencies it would
give us an impulse, but instead set the difference between each
oscillator to be 1 cycle + delta, where delta is very small, maybe
1Hz or less.

What you will hear in Csound on a 64 bit system is a ** beautiful **
effect as a "rainbow" of all frequencies apparently plays in sequence.


Now, if the oscillators are very good the spacing will be equal and
the effect will sound crystal clear with individual frequencies popping
in and out in a regular stream.

If the oscillators are innacurate (because of distortion, bit depth,
asymmetry etc) then you will hear a muddled effect. Any deviation from
a perfect sine must introduce other hamonics and these come out in
the sequence, so it's an empirical/practical way of testing the quality
of a digital system without any special test equipment or measuring
other than your ears.

Hardly very scientific, but roughly from the few chances I've had
to try it on different systems...

Csound - the King, all bow before Csound 
Nyquist/CLM - a close second on some machines
Puredata - Not bad, but not good, you can tell something is broken
Max - pretty damn awful
Reaktor - forget it

So I believe there is a difference between Max and Pd and Max is the loser.
But of course all software is in development. And it must be said;

1) this only test oscillator accuracy but may also test fp accuracy (I haven't
thought it through in detail)

2) It depends how you do it. For example, using table oscillators that precompute
is different than taking the cosine (maybe Taylor or poly approximated) of
a phasor.


If I had all systems running and time I'd try it again, but I don't. If we could
define the exact parameters for a patch to eliminate variables I think Rissets 
diffraction is a very good test that reveals the quality of digital synthesis
software.







On Thu, 06 Mar 2008 21:02:00 -0500
marius schebella <marius.schebella at gmail.com> wrote:

> what I experience sometimes when I do very basic stuff like using 
> phasors, is that I hear weird comb filtering of my environment after I 
> put down my headphones. similar as if you look into bright light and 
> then close the eyes, and you still see a review-image.
> regarding the difference between pd and max: are you talking about the 
> music that people produce or are you talking about the digital signal 
> process?
> m.
> 
> Damian Stewart wrote:
> > hey,
> > 
> > i was talking to a Portuguese musician tonight (Miguel Cardoso is his name) 
> > and he was saying that he thought that Pd sounded much better than Max - a 
> > fuller sound with the oscillators, he said.
> > 
> > i hadn't really thought about this before, but i do know that to my ears my 
> > Pd patches sound a lot richer than most Max/MSP stuff that I've heard - not 
> > sure whether that's my source material or patches or whether it's at a 
> > deeper architectural level than that.
> > 
> > anyone have any evidence, anecdotal or otherwise, to confirm this? reasons 
> > why this might be the case?
> > 
> 
> 
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