JBL L Series Manual page 3

recommend suitable interconnects and speaker wire to best
complement your system.
The length of the speaker wire will depend on the location of the
loudspeakers and the amplifier. Since the final positioning of the
loudspeaker will be determined by careful listening, you may want
to arrange a temporary wiring layout that will allow the moving of the
loudspeaker to experiment with placement. When the best loud-
speaker position is determined, permanent connections may be
made using the shortest cable runs possible. Both left and right
speaker wires should be the same length. In some systems, the
amplifier may be located near the loudspeaker system and may be
connected using a short length of speaker wire. Although a relatively
long cable between the preamplifier and main amplifier is required
by such a hook-up, the benefit of a short amplifier-to-loudspeaker
connection will often outweigh the drawbacks.
Connections to the loudspeaker system are made at the terminals
located on the back of the enclosure. These terminals permit a
variety of connection methods.
The most straightforward connection is made by directly connecting
clean bare wire. This way the connection is made by stripping 8-10
mm of insulation off the loudspeaker wire and passing the bare wire
through the hole in the binding post. If the wire is too thick to pass
through the hole in the terminal in one single bundle, separate the
copper wire into three equal bundles, then pass the center bundle
through the hole in the terminal. Wrap the remaining bundles
around the binding post and twist together with the center strands.
The knob can now be tightened securely, and any excess wire that
is not in contact with the binding post surfaces should be trimmed
to avoid short circuits.
A very convenient way of connection is the use of 4 mm banana-
type connectors, which are then, in turn, connected to the binding
posts. Bear in mind, however, that the number of contact points
should be kept to a minimum, and at the same time each contact
should be as tight as possible.
For the same reason, we recommend the use of the highest quality
spade connectors, expertly connected to the selected cables.
Spade lugs will make the best possible connection between the
speaker wire and the loudspeaker system, minimizing any contact
resistance that might degrade the sound ever so slightly.
Any connection in an audio system should not be considered "good
forever". All connections should be inspected and cleaned or
remade periodically. Frequency of maintenance depends on the
materials involved in the connection, atmospheric conditions and
other factors. Consult your dealer for specific recommendations.
It is essential that both loudspeakers in a stereo system have the
same polarity with respect to the input signal (are in "phase").
J B L L-Series are designed to produce a positive pulse when a
positive signal is applied to the red input terminal.
If the driver cones of the two loudspeakers do not move in the same
direction for a given voltage at the input terminals, there will be a
lack of stereo definition and a loss of deep bass.
We recommend experimenting with the polarity of the speakers,
since recordings, program sources or power amplifiers can invert
the polarity of the signal. The "correct" connection is the one that
yields the best audible results. Be sure to reverse both left and right
connections to keep the systems in polarity.
BIWIRING
J B L L-Series loudspeakers may also be connected to the amplifier
using two lengths of wire. The biwire connection method offers
several options and advantages.
The system's internal dividing networks are electrically separated at
the low frequency to mid range/tweeter transition. External strapping
bars connect the two parts of the network when a single wire
connection is used. The system is shipped from the factory with the
strapping bars in place. By removing the bars, connections may be
made to the individual network sections using two wires (four con-
ductors) as shown in Figure 1. The wires used may be of the same
type for both low frequency and high frequency sections. The
advantages are that wire effects (resistance, inductance, etc.) are
reduced and intermodulation of low and high frequencies in the
cable are avoided. Specialized wires for low frequency and high
frequency sections may yield excellent results in some systems. In
either case, low frequency cable should be as short as possible,
and the left and right cable for each section must be the same
length. If the cable to one speaker system is longer than the one to
the other speaker due to the distance from the amplifier, make sure
not to wind the excess cable up in the form of a coil. Instead, try to
arrange it in figures of eight, as this will minimize the inductance of,,
the cable run and thus minimize cable losses at high frequencies.
CAUTION: Never connect two amplifiers to the same loudspeaker
without first removing the strapping bars. Operating two amplifier
channels with the bars in place may seriously damage the
amplifiers and void the warranty.
Fig. 1: L input
Low Frequency
Amplifier
Fig. 2: L input
Low Frequency
Low Frequency Amp
High Frequency
High Frequency
High Frequency Amp