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Since early 1999, an improvement in surround technology known as Surround EX uses a variation on
matrix methods to produce a rear surround channel. When this option is called for, the surrounds will have to be
reallocated electrically from the booth, as shown in Figure 32. Dolby Laboratories has provided the necessary
booth equipment to enable this change to be made easily.
VI. ELECTRICAL INTERFACE
A. JBL Polarity Conventions:
For reasons having to do with long-term product continuity and performance consistency in the eld,
many of JBL’s older transducer and systems groups have what is called “negative polarity convention,” that is, a
positive-going voltage on the (+) or red terminal will result in an inward motion of the cone or driver diaphragm.
Positive polarity (so-called EIA polarity) species that a positive-going voltage on the (+) or red terminal will result
in an outward motion of the cone or driver diaphragm. (When applied to systems, the polarity convention refers to
the observed motion of the LF driver only.)
Figure 31: Surround loudspeaker
placement. 12 surrounds in L
and R, plan view (A)
Surround loudspeakers
shown in section view (B).
Figure 32: Surround loudspeaker placement. 12 surrounds in L, C and R, plan view.
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