[sdiy] dx, chorus and Spock

[Scott Gravenhorst]

Don Tillman <don at till.com> wrote:
>   > From: Gene Stopp <gene at ixiacom.com>
>   > Date: Thu, 15 Aug 2002 16:23:52 -0700
>   > 
>   > Do precise waveforms sound better than "sloppy" ones? 
>
>I have a theory about our sense of hearing: I claim that we can't hear
>waveforms or harmonics very accurately at all, but we are remarkably
>sensitive to the subtleties of the *process* that's making the
>waveform.

Using a square wave, without any filtering to isolate them, I hear
quite well and quite distinctly the fundamental AND the 3rd harmonic. 
Higher than that, I can't pick them out, but square waves sound, to me,
very much like a fundamental plus a perfect fifth in the next octave. 
I'm not sure if that's what you mean, but I can hear this.

>Why?  Millions of years of evolution and survival of the species.  If
>there's a bear hunting you down in the forest, the ability to
>accurately discern what's causing a funny noise is vital.  Identify
>the footsteps, the size of the animal, which direction, how far away,
>how fast, on what surface...  In such a situation, the level of the
>seventh harmonic is just not important.
>
>So I'd say that precise oscillator processes sound better than sloppy
>ones. 

If things like *perfect* sawtooth waves sound "better" (highly
subjective statement I think), then why in God's name would we EVER
want to filter?  Using a filter changes the harmonic structure such
that in most cases, the resulting wave is not a perfect anything.  But
we do use filters.  Why?  Because doing so gives us a sound that is
correct for our purpose at the moment.

Waves are waves.  Geometric ones aren't any "better" than ones that
don't look perfect on a scope, they just have names that describe their
shape on a scope screen.  Some waves with warts sound good, others may
not.  I think that what a wave looks like on a screen has nothing to do
with whether it sounds "better" or not.  Harmonic content is what makes
a sound, and only harmonic content.  How many of us sit there and tweak
up a patch while watching a scope?  Special purposes notwithstanding,
I'd say most of us just use our ears and noodle 'til we smile.  I've
looked at waveforms after doing that and honestly, they can look pretty
nasty.  

Perfect waveforms do have their purpose, such as sweep generators, or
slope generation for accurate measuring circuits.  But this is more in
the field of instrumentation, not instruments.

I'd say Gene had a damn nice filter that was doing a great job of
isolating the harmonics.  Other repeating waveforms whether a "perfect"
something or not would still be made up of those same harmonics, just
different levels and phase relationships.  I'd bet that Gene's filter
could have isolated those harmonics in a lumpy weird looking wave too,
as long as it was frequency and phase stable and noise free.

>(And yeah, Spock's Beard is great.  Especially live; they put on a
>wonderful show.)
>
>  -- Don
>
>-- 
>Don Tillman
>Palo Alto, California, USA
>don at till.com
>http://www.till.com
>

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