JBL P-20t, Руководство пользователя

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03
System Design
The P-20t, with its built-in in-line
crossover, is designed to provide added
high-frequency performance to any
mobile audio system.
The P-20t may be used as the primary
tweeter in a system or as an add-on
tweeter or super tweeter used to improve
the high-frequency response of an
existing system.
The in-line crossover acts as a high-pass
filter as well as a protection device that
keeps the tweeter from being overexerted
by low frequencies that it was not
designed to reproduce.
Under normal circumstances this
crossover should not be bypassed or
removed for any reason. Bypass the
installed capacitor only when using an
outboard active crossover or a custom-
built passive crossover set above 5kHz.
Component Placement
Because of the P-20t’s small size and
extremely versatile mounting options,
there is an almost infinite number of
placement options to achieve excellent
sound quality in any vehicle. Please
consider the following statements to
help you get the most from your system.
1. The most spacious stereo image is
achieved when the P-20ts are placed
as far apart as possible.
2. The best center image will be achieved
when the distances from the left
speaker and the right speaker are as
equal as possible from your listening
position. This is most easily achieved
by placing the P-20ts as far forward as
possible.
3. Treble is directional in nature. This
means that high frequencies are
reduced as you move off the tweeter’s
axis. The angle mounts will allow the
P-20ts to be pointed across the car to
the listener on the opposite side (as
shown in Fig. 3). This will make each
listener slightly off-axis to the tweeter
that is closer to that listener, which
helps to compensate for the fact that
the listener is always closer to one
tweeter than to the other.
4. The best system integration is
achieved when the tweeter is mounted
close to the midrange speaker. This
helps smooth the transition from the
midrange and tweeter crossover point.
Choosing mounting locations that satisfy
all the above criteria will provide the most
satisfying performance.
Figure 3
Tweeter Output Level
The P-20t is a very efficient tweeter. If
there is a need to lower the tweeter out-
put, a 4-ohm / 5-watt resistor can be
connected in series (before capacitor)
with the P-20t, as shown in Fig. 4.
IN-LINE CROSSOVER
(mylar capacitor)
cut wire here
before capacitor
4 ohms /
5 watt (min)
resistor.
Figure 4
To avoid short circuits, make
sure that heat-shrink tubing or
electrical tape is used to cover all
exposed wiring.
Installation
Warnings and Tips
Be careful not to cut or drill into fuel
tanks, fuel lines, brake or hydraulic lines,
vacuum lines or electrical wiring when
working on your vehicle. Inspect behind
panels before you cut or drill.
Do not use the P-20ts unmounted. Failure
to secure this product could result in
damage or injury, particularly in the event
of an accident.
Always disconnect the ground wire from
the battery before doing any work on the
vehicle.
P-20t owner's Manual 9/16/98 4:16 PM Page 3