Comments in line.
Tentochi wrote:
> 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.
There is no "real" relationship. The markings indicate that switching
from 16' to 8' will increase the oscillator's pitch by one octave. The
pitch is only relative. In a 1v/oct synth ths switch would merely add or
subtract 1v per "step" of this switch.
Previous posts have indicated that the pipe length is relative to the
key pressed on the organ keyboard. In most circumstances, the lowest key
on the organ manuals is two octaves below middle C. This does not mean
that the pipe played is exactly 16' if a 16' stop is drawn, but is
approximately that size. 16' feet is its "speaking" length. There are
factors of the pipe's "scale" (relative width and depth to the height)
that will have an impact on the pipe's actual length. This is more
important in an organ in that the pipe is "Hard wired" so to speak, to
the key being pressed. This is not so with an oscillator which can be
tuned to any pitch.
>
> 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.
>
Pipes can also be bent (Mitered) to fold back upon themselves.
> 2. Use a synthesized tone with a large subwoofer.
>
Yawn.
> 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.
>
Perhaps what you are refering to is the "resultant bass". This is an
organ stop using the harmonic series to fool the ear into hearing a
lower tone. Given a 32' resultant bass, pressing a pedal key (where this
is most commonly used) will play two pipes simultaneously, one at 16'
(one octave above) and one at 10 2/3' (one octave and a fifth above).
This will give the impression that one is hearing the 1st and 2nd
overtones (2nd and 3rd harmonics) of an even lower note which does not
exist. This technique has varying levels of success.
Regards, Scott