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
max
is determined by the amount
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
Connecting Your Subwoofer to
an Amplifier:
Configuring the voice coils:
Figure 4. Terminal locations
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.
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.
Figure 6. Connecting the voice coils in
series (12 ohms)
TOP COIL
IN GAP #1
DRIVES CONE
FORWARD
ALUMINUM
COVER
2nd
TOP PLATE
1st
TOP PLATE
POLEPIECE
BOTTOM COIL
IN GAP #2
DRIVES CONE
REARWARD
CONE
SPIDER
GAP #1
GAP #2
MAGNET
OVERHANG
DETERMINES
X
max
TERMINAL
JUMPER
INTACT
TERMINAL
JUMPER
INTACT
+
RED
TERMINAL
BLACK
TERMINAL
TERMINAL
JUMPER
REMOVED
TERMINAL
JUMPER
REMOVED
+
RED
TERMINAL
BLACK
TERMINAL
05
PRO POWER
TM
