[sdiy] Now tube type (6SN7) flip-flop circuit.. Follow up...

[Mike Bryant]

When you pull several stops out to create the particular complex sound you require, all the pipes receive the pumped air at the same time every time a note is played.  So you do get a particular phase relationship at the beginning, and at 21 deg C this phase relationship will be maintained as the pipes are exactly an octave apart.

I said "difference in frequency variation", not "difference in frequency", i.e. as the temperature changes different pipes vary in the number of cents their resonant frequency moves.  Hence at temperatures other than 21degC the pipes are not exactly an octave apart so you get a 'duller' sound when cold and a 'brighter' sound when too warm.

The middle C pipe(s) are indeed 4 feet long, or 2 feet long if stopped (end closed)

________________________________
From: Donald Tillman <don at till.com>
Sent: 02 February 2024 01:18
To: Mike Bryant <mbryant at futurehorizons.com>
Cc: Synth DIY <synth-diy at synth-diy.org>; Tony Allgood <oakleysound at gmail.com>
Subject: Re: [sdiy] Now tube type (6SN7) flip-flop circuit.. Follow up...

> On Feb 1, 2024, at 3:42 AM, Mike Bryant <mbryant at futurehorizons.com> wrote:
>
> Actually on a pipe organ, the phase rarely matters as all the octave spaced pipes are only in perfect phase sync at 21 degC.  As they are such different sizes at any other temperature there is a difference in frequency variation across each pipe, which is why some organs can sound quite crap in the morning, sort of ok for afternoon weddings and absolutely glorious in the late evening.

I'm not sure what you mean by this.  I don't see any mechanism that would phase-sync pipes that are tuned an octave apart.  What does a "difference in frequency across each pipe" mean?

Pipe organ dimensions are very large compared to the wavelength of middle C, which is like 4 feet.  It's not at all clear what phase even means in such a situation.

  -- Don
--
Donald Tillman, Palo Alto, California
https://www.till.com
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