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the other coil's magnetic gap. This will
cause magnetic braking, which will slow
the cone's motion and prevent damage
due to overexcursion. For a GTi Series
woofer, X
is determined by the amount
max
of voice-coil overhang between the first
and second top plates. See Figure 3.
Thermal power handling is far superior
to a conventional DVC woofer using
voice coils of a similar diameter and
length because Differential Drive provides
twice the heat-dissipating surface area
and two top plates to transfer heat to
the magnet-cover fins.
Figure 3. JBL dual-gap design
CONE
TOP COIL
IN GAP #1
SPIDER
DRIVES CONE
FORWARD
1st
GAP #1
TOP PLATE
POLEPIECE
2nd
GAP #2
TOP PLATE
BOTTOM COIL
IN GAP #2
DRIVES CONE
ALUMINUM
REARWARD
COVER
Connecting Your Subwoofer to
an Amplifier:
Configuring the voice coils:
Figure 4. Terminal locations
MAGNET
OVERHANG
DETERMINES
X
max
Note: Unlike conventional DVC
subwoofers, the two sets of terminals
are configured so that both positive (+)
terminals are on one side of the frame
and both negative (–) terminals are on
the other side. GTi Series subwoofers are
shipped with terminal jumpers installed
which configure the two 6-ohm voice
coils in parallel for a 3-ohm load.
Note: Both voice coils MUST be
connected to the amplifier in series
or parallel.
PRO POWER
Figure 5. Connecting the voice coils in
parallel (3 ohms)
Note: Connect the coils in parallel if you are
connecting a single woofer to an amplifier.
TERMINAL
TERMINAL
JUMPER
JUMPER
INTACT
INTACT
RED
BLACK
TERMINAL
TERMINAL
+
Figure 6. Connecting the voice coils in
series (12 ohms)
TERMINAL
TERMINAL
JUMPER
JUMPER
REMOVED
REMOVED
RED
BLACK
TERMINAL
TERMINAL
+
TM
05
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