source file: m1400.txt
Date: Wed, 29 Apr 1998 16:57:05 -0400

Subject: RE: JI Tuning Resolution

From: "Paul H. Erlich" <PErlich@Acadian-Asset.com>

I wrote,

>Now if the onset times are controlled really accurately by MIDI, and
>let's say a 90-degree phase shift is chosen so that the energy at 1000Hz
>is twice that from one instrument, then you're doing okay, right?

>If both instruments are electronic, and their signals are mixed into one
>speaker, there will be no spatial nodes or antinodes.

Note, however, that if the two tones have the same relative phases of
their partials, then their 2000Hz harmonics will have a 180-degree phase
shift and potentially cancel each other out. This is another probably
undesirable musical effect. Add more tones to the chord and the
potential for cancellations increases. Thus I must conclude that under
no circumstances is exact JI desirable, unless all tones are played
through one loudspeaker and one exerts full control of the phases of all
partials of all tones so as to eliminate anomalous interference. (Tones
sound quite similar, but not exactly the same, when the relative phases
of the partials are messed with; the characteristic "brassiness" of
brass instruments is due in some part to the sharp spikes in the
waveform which Gary mentioned.)