JBL Professional
®
Intellivox ADC Installation Manual
15
201402/ADCIM
CORRECTION EQ AND HIGH-PASS FILTER
Many building PA systems will include some provision
for equalisation (EQ) adjustment at the signal processing
stage, or within the power amplifier (as with the JBL AXYS
PB-400 and PB-800 amplifiers). Adjusting EQ to achieve
maximum system intelligibility is a normal part of the
commissioning process, though it should be noted that
measured intelligibility will be greatly affected by several
other factors not immediately under the designer’s control,
such as reverberation time and ambient noise levels. If
external EQ adjustment is not available, it may be desirable
in some applications to modify the frequency response of the
loudspeaker itself.
The frequency response can be altered by means of two
switches labelled ‘EQ’ and ‘HPF’. These switches are located
behind the inspection plate as indicated in fig.9.2 (Model
V90) and fig.9.3 (Model H90).
The EQ switch has two positions. The EQ is disabled if the
switch is in the ‘Flat’ position. The mid-cut EQ correction
is indicated in fig.10.1 (Model V90) respectively fig.10.3
(Model H90). The factory default setting is with EQ enabled
(flattest SPL versus frequency response). If the EQ is
disabled the maximum achievable SPL is somewhat higher,
at the expense of a SPL response that is less flat.
The HPF (high-pass filter) switch also has two positions.
The high-pass filter is disabled if the switch is in the ‘Flat’
position. The frequency response of the high-pass filter
is indicated in fig.10.2 (Model V90) respectively fig.10.4
(Model H90). The filter response is slightly dependent on
the tap setting, the curves are valid for the 100 W tap. The
factory default setting is with the high-pass filter enabled,
this setting is most suitable for voice applications.
Note that the high-pass filter might have to be disabled in
case of 3rd-party line monitoring applications that make
use of a DC signal. DC will be blocked by a series capacitor
if the high-pass filter is enabled.
If the monitoring system uses an end-of-line unit, and DC
input to the loudspeaker should be blocked, the high-pass
filter should be enabled. If the monitoring system is to be
used in conjunction with the loudspeaker(s), without end-
of-line unit, the high-pass filter should be disabled.
Note that this does not apply to the integral
load monitoring of the JBL AXYS PB-400/PB-800
Industry Amplifiers; these amplifiers do not use a
DC signal for load monitoring purposes.
SECURING THE FRONT GRILL
Option 1.
After making the connections and setting the
power tapping, the front grill may be replaced. Do not
replace the protective foam! Align the four locating spigots
with the four larger holes in the back of the grill frame and
push the grill back on, ensuring that all four spigots locate
positively with the retaining clips within the holes.
Option 2.
The front grill may be secured more permanently
with the (supplied) M4 security screws. These need to be
fitted one at a time before replacing the grill.
fig.10.1 - V90 correction EQ
fig.10.3 - H90 correction EQ
fig.10.4 - H90 high-pass filter
fig.10.2 - V90 high-pass filter
