7.1-C
HANNEL
S
YSTEMS
In a 7.1-channel system, two speakers are added for rear fill, in addition to the sur-
round speakers in a 5.1-channel system. The two additional speakers are placed on
the rear wall or near the rear wall in the ceiling (see Figure 6).
S4Ai M
ODES OF
O
PERATION
The S4Ai multipole ambient surround speakers feature the unique capability of
being configured in any of three operational modes. Choose between Dipolar or
Bipolar operation for cinema reproduction, and Direct Radiating for music. Both Dipole
and Bipole modes are diffusive, meaning there is less energy on-axis than off-axis
relative to the front of the speaker baffle. As Figure 7 indicates, the S4Ai’s omni-
directional woofer faces toward the listening area, while dual sets of tweeter/
midrange (diffuse) arrays face toward the front and rear or from side to side in
the room. In Dipole mode the arrays play out of phase in relation to each other,
and in Bipole mode they play in phase with each other.
To activate the Direct Radiating mode for music playback, use the JBL Synthesis
electronics package, including the SDP-40 surround processor, to trigger the
autoswitching relay in the loudspeakers. The input to the trigger connection is
located at the bottom of the speaker, next to the speaker terminals (see Figure 8)
and accepts two-conductor, #24 to #16 AWG wire. The relay is activated by a con-
stant 12V DC signal.
S4Ai W
IRING
G
UIDE
Each S4Ai speaker can be wired in single- or dual-drive mode. The best performance can be obtained by installing
four S4Ai speakers in a 7-channel system and wiring them in single-drive mode; that is one amplifier channel per
S4Ai speaker. If only two S4Ai speakers can be used in a particular application, then they should be wired in dual-
drive mode so as to gain the advantages of a 7-channel system. Each S4Ai speaker receives amplification from two
channels – side and rear – which can only be accomplished in the Bipole mode.
7
R
C
L
SIDE
LEFT
SIDE
RIGHT
REAR LEFT
REAR RIGHT
Figure 6. 7.1-Channel system
SPEAKER INPUT #1
SPEAKER INPUT #2
Figure 8.
Single-drive – Dipole or Bipole
operation only – two-cond.
speaker wire
Dual-drive – Bipole operation
only – four-cond. speaker wire
Single-drive w/Direct – Dipole or Bipole
and Direct Radiating operation – two-cond.
speaker wire and two-cond. trigger wire
Dual-drive w/Direct – Bipole and Direct
Radiating operation – four-cond. speaker
wire and two-cond. trigger wire
Figure 7.
S
PEAKER
P
LACEMENT
