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Phase Shifting and Space Trajectories (Part 2).

As we have seen in an earlier article, phase shifting and panning modules play an important part in the synthesis process, for they allow sounds to be easily positionned in a space/time continuum.

In general, panning should always be coherent with the inherent behaviors of the musical score : it should only be used to enhance the spatial subtleties of the sound material in time.

One of my musical mentor, Morton Subotnick, used a tilted architect table to compose his e-music scores, and to draw all panning trajectories in Quad space.

Figure 1a, shows a typical linear panning distribution between a left and a right channel, using control voltages. Regretfully, some commercial panning modules designs often exhibit a "drop" in the L/R signal at the half-power point.
Figure 1b, shows a Serge Equal Power panning distribution between a left and right channel, using control voltages. This superb Serge design allows a much smoother panning operation between the two channels.

Evidently, not all sound materials should be panned systematically : there are some restrictions in panning some specific musical works. Indeed, it is hard to imagine the music of a Jazz combo or Beethoven's 9th Symphony, wildly panned in a stereo or QUAD field!

Why ? Because of acoustical, cultural and esthetical reasons! It is important to remember, that if you plan to synthesize acoustical instruments, you have to adhere to these set conventions. Also, let's not forget, that all instruments in an Orchestra are positionned, once and for all, to their assigned space on the stage (see Figure 2.).

In this case, it is best not to use a voltage controlled panning module. Instead, use the passive pan function of your audio mixer to place each instrument into the assigned stereo field.

As a reminder, always calibrate your audio mixer for symmetric stereo use under normal circumstances (see Figure 3a).
Notice, the gain (+3dB)  between two channels set at 12o'clock (see 3b). Also, check the dramatic gain/loss between two channels set
in an assymetric setting (see 3c and 3d)!

Finally, bear in mind that the range of LFO/Audio signals are highly non-linear (see Fig4) !

Andre Stordeur
July 2003