inboard side of Iheir respective bass units. If Ihe loudspeaker system is to
have low. midrange and high frequency components, placing them in a
vertical line (low, mid and high) will generally provide widest and most
uniform sound distribution within the listening room. For best acoustics,
components should be as close together as practical, but al least 50 mm
(2 in) apart to maintain the structural integrity of the baffle panel
Positioning the high frequency driver near, or directing its output toward,
listener ear level will usually result in the most realistic performance.
Caution:
To prevent serious damage, never connect a midrange or high
frequency transducer directly lo any source capable of generating low
frequency signals. Connection should be made only to the respective mid
or high frequency terminals of the recommended JBL frequency dividing
network. If separate amplifiers are used for the various components of the
system (bi-amplification or tri-amplification). a properly designed high-pass
filter must be used-in addition to an electronic frequency dividing network
- t o protect the transducer from turn-on transients and other accidental
low frequency signals.
LE5H Midrange Transducer
The LE5H must be housed in an isolated
sub-chamber to prevent interaction with the low frequency loudspeaker.
For smoothest frequency response the sub-chamber should have a
minimum volume of 1.3 litres (80 in
3
), and should be filled lo moderate
density with fiberglass acoustic damping material. A sub-chamber can be
fabricated of a tube having an internal diameter of 114 mm (4 ft in) and a
length of 130 mm (5 in) flush mounted on the baffle panel and closed at
its interior end. Insert the inpul leads through a small hole punched in the
side of the tube (use caulking compound to maintain an airtight seal), and
install the damping material. Press the tubular vinyl gaskel into the groove
on the back of the mounting flange, connect the input leads, place the LE5H
into the tube and secure it to the baffle panel with the four self-tapping
screws provided.
LE21H High Frequency Direct Radiator
The LE21H mounts directly to
the front of the baffle panel using T-nuts and machine screws The cutout
should be 105 mm
[AM
in) in diameter, with additional clearance provided
for the terminals (see the diagram on the next page). The flat gasket on the
rear of the mounting flange will form an airtight seal. Place the LE21H in
the mounting cutout and lighten the screws a little at a time, maintaining
even pressure on the gasket. Do not overtighten,
075 And
077
The 075 and 077 mount from the rear of the baffle panel in
an 81 mm (3?i« in) diameter cutout: the driver is held in place by four
machine screws extending through the baffle panel. Place the tubular vinyl
gasket around the horn and seat it against the mounting bracket prior to
inserting the unit into the baffle cutout. NOTE: The 077 should be mounted
with the slot vortical, as shown, to provide maximum horizontal dispersion.
The 075 produces a conical sound distribution pattern and needs no par-
ticular mounting orientation
