[sdiy] piano spectrum analyzer

[Sean Costello]

Actually, I think it will work, at least to a degree. The strings can be
excited into harmonic motion, but their tendancy will be to resonate at only
the harmonic that is closest to the input signal. Nonlinearities within the
strings will cause a little bit of higher harmonics to be excited, but the
errors this would generate would be similar to the frequency aliasing you
see in an FFT.

The big problem would be the "windowing" of the sound. Frequency analysis
has to deal with the fact that time and frequency are interconnected; the
more frequencies you want to capture, the longer the window you need. The
piano won't have this exact problem, but the resulting sound will be
hideously smeared in time, making analysis difficult. It would be similar to
using an FFT with feedback (which seems pretty close to Miller Puckette's
phase vocoder patch used to emulate the piano reverb).

Maybe if you dampened all the strings you could get a result, but at that
point the soundboard / enclosure resonances might be stronger than the
strings.

Plus, the thing would be heavy to carry around.

Sean Costello


----- Original Message ----- 
From: "harrybissell" <harrybissell at prodigy.net>
To: "Tim Ressel" <madhun2001 at yahoo.com>
Cc: "synth-diy" <synth-diy at dropmix.xs4all.nl>
Sent: Monday, December 13, 2004 9:01 PM
Subject: Re: [sdiy] piano spectrum analyzer


> well of COURSE this crazy idea will not work... because the strings can
> all be
> excited into harmonic motion as well...
>
> you might want to use spherical resonators...which are VERY prone to
> exciting only
> a fundamental resonant more.
>
> MAybe you will write a book detailing your efforts... might I suggest
> "On the sensation of Tone" as a possible working title :^P
>
> H^) harry
>
> Tim Ressel wrote:
>
> > Yo,
> >
> > I have always wanted to try this: put guitar-style
> > pickups on a piano and turn it into a spectrum
> > analyzer. If a loud sound is impinged upon the strings
> > (say a nice big speaker) they will be excited by the
> > sound, and the pickups will turn that into a signal.
> > Just need about a zillion amp/detectors...
> >
> > --TimR
> >
> >
> >
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