JBL LSR28P, Техническое и сервисное руководство

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PRODUCT OVERVIEW
The Linear Spatial Reference, LSR, series of professional active loudspeakers is
especially designed for professional applications. Its two-way architecture employing a 1-
inch damped titanium-composite tweeter and an 8-inch, Differential Drive with Dynamic
Braking Voice Coil woofer reproduces the audible spectrum effortlessly.
The woofer's patented, Differential Drive Mechanism provides a greater voice coil surface
area allowing the LSR28P to better dissipate excessive voice coil heat. Since voice coil
heat directly affects the compression of the cone, the sound from traditional speakers will
deteriorate when used during long sessions. JBL has effectively devised a method of
releasing this heat. More aptly, by spreading the heat over a larger surface area so that it
is absorbed by the surrounding magnetic structure, this reduction has caused two
noticeable advantages--longer useful transducer life and a flatter impedance curve
throughout the frequency spectrum. What this means to the user is that the LSR28P will
exhibit consistent performance at low, medium and high levels of volume during the
entire musical session.
The Dynamic Braking Coil prevents excessive speaker cone excursion during those high
levels. Although, the LSR28P does require a pre-amp to provide a nominal -10db level to
be used for proper operation, the LSR28P provides the final signal frequency processing
and power amplifier modules.
The composite signal is efficiently separated into the low and high frequency components
by utilizing BI-amplified topology for signal dispensation. Each frequency-specific
element is sent to the respective power amplifier. For the low frequency section, a
discrete, push-pull Darlington-configured amplifier is employed with a measured gain of
15 or an increase of 23dB. For the high frequency section, an integrated circuit capable of
being driven to 100 watts of continuous output with a gain of 14 is used.which is
comparable to a 21db gain. Both amplified signals are sent to the matched low and high
frequency proprietary transducers for audible reproduction. Employing this method of
frequency separation eliminates the total harmonic and phase distortion that commonly is
associated with passive networks.
The final result is a time-independent, smooth, and distortion-free sound at all levels of
output! And, since the entire LSR Series has been designed with the philosophy
incorporating the best components available to attain the highest performance possible
for a particular targeted area, they are able to faithfully reproduce their respective
frequency range. For the LSR28P, the entire audio range from a low of 50Hz extending
to 20KHz.and beyond with a crossover frequency of 1.7KHz is reproduced. (The
frequency response for the LSR28P amplifier is shown graphically on the following
page.) Needless to say, they have become the standard speaker monitors used in
professional studios and by audiophiles alike.
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