JBL GTH400-20107 - Manual (Page 7)

3. System Design Using
the GTH400
3.1 Speaker Requirements
When used in the non-bridged mode a
group-channel of the GTH400 can
easily drive two 2-ohm speaker loads.
When only one speaker is connected to
the left and right outputs of a group,
virtually any conventional speaker may
be used. When two speakers are
connected in parallel to a single output
(left or right) of a given group, each
speaker must have a minimum
impedance of at least 4 ohms. This
ensures that the combined load will not
drop below 2 ohms. Although the
amplifier will not be damaged, load
impedances lower than 2 ohms will
eventually cause the amplifier to
overheat, activating the protection
circuits and causing the unit to shut off
until it cools down sufficiently.
When a group of the GTH400 is in
bridged mode, the combined
impedance of the speaker (or speakers)
connected to the bridged channels
should be at least 4 ohms. As in the
example above, sustained operation of
the GTH400 in bridged mode with less
than 4 ohms will likely cause
overheating.
The GTH400 must not be used with
speakers that have either one of their
input terminals wired to the frame of
the speaker or to the chassis of the
vehicle.
(+)
(–)
(+)
(–)
Parallel Wiring
Series Wiring
2 ohms
Nominal
Impedance
8 ohms
Nominal
Impedance
4 ohms
4 ohms
4 ohms 4 ohms
6
GTH400-20107 06/03/98 15:49 Side 6