MOTM

You may be overthinking the issue. When a synthesizer uses 'footages' to
mark off an octave switch, it's basically just saying that "16' is an octave
below 8'" and "2' is two octaves above 8'." You can tune your VCOs to ANY
frequncy, and changing the "footages" just switches octaves in that way,
relative to a "base footage" similar to the way all of the notes of an organ
keyboard relate to a base footage marking.

As mentioned by others, there are real, physical reasons why a pipe organ
uses footages --- pulling stops for footages switches in/out ranks of pipes
of different lengths, and therefore different "harmonics," in the science of
the time at least. Synthesizers simply adopted the rough thinking of the
pipe organ in this respect. 

It was just a way of applying an accepted musical instrument concept to the
new machine that makes sounds electronically. There is no absolute
correlation on a synthesizer between a footage and a frequency. It's a very
simple thing going on here. Some here have tried to explain how the length
of a pipe affects resonance _on a pipe organ_, but if you're wondering why
frequencies on a Korg MS-10 don't match what they've written, it's because
you're dealing with a synthesizer, not a pipe organ.

Just treat the powers-of-two as octave switching and don't overthink the
issue.



-----Original Message-----
From: Tentochi
To: motm@yahoogroups.com
Sent: 2/21/2003 8:22 PM
Subject: Re: [motm] Pipe Length Frequency Equivalents

The responses have been VERY interesting and
insightful.  But they really didn't answer my
question.

What is the relationship (if any) between the pipe
lengths marked on a synthesizer and the frequency
output.  The frequencies mentioned in the replies seem
too low for what I hear on my synths.

That did me think of the psychoacoustics of pipe
organs.  I don't think a lot of churches can
accomodate or afford the largest pipes.  So I have
seen 3 things done to accomodate this:

1.  Lay the pipe sideways on the floor.

2.  Use a synthesized tone with a large subwoofer.

3.  Use an implied tone.  Off the top of my head, I
can't remember exactly how this is achieved.  But this
is the most interesting IMO.

This also brings up the topic of resonant frequencies
of different spaces.  Of of my favorite techniques
when perform is to tune my kick (TR-909) to the
resonant frequency of the performance.  You want to
talk about a hell of a kick.  People can't figure out
how I am doing it.  I have seen a couple of other
performers also use this technique.  Most of my
current work does not have any kicks in it
unfortunately.  I have NOT tried pre-tuning my synths
to the resosant frequency yet.  Has anyone else tried
this?  I think the cool thing is that it comes in
resonating as opposed to tuning it manually during the
performance.  Shake the rafters!  I guess there is the
potential of literally bringing the roof down with a
sufficiently strong sound system and a sufficiently
weak roof.

Mind Your Bass Bins Mate!
Shemp

> On many traditional analog synthesizers, the octave
> was denoted by "equivalent" organ pipe lengths.  I
> think the extant of the range is something like 64",
> 32", 16", 8", 4", 2", 1".  Typically the range is
> some like 16" to 2".
> 
> What is the corresponding frequency range for each
> of
> these pipe lengths?  What notes are the pipes
> themselves tuned to?  Is this the first note for
> that octave?

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