the outputs be in phase. This is relatively easy to ac-
complish electrically, and much more difficult acoustical-
ly where it really counts. Therein ties the reason for the
phase correction capabilities of the crossovers. They are
able to alter their phase response to compensate for
phase problems in drivers and their cabinetry.
CROSSOVER FREQUENCY
should be set primarily
based on the driver manufacturer’s recommendations.
Some fine tuning may be necessary depending on the
specifics of the system. Caution should be used when
straying too far away from factory guidelines. Crossing
over a horn or other high frequency component too low
may result in permanent damage. Low frequency drivers
generally can be driven with hi frequencies with no ill
results other than poor sound. It is better to err on the
high side than the low.
INPUT AND OUTPUT LEVELS
should generally be set
at or near the unity gain marks. There should be no
reason to take gain in a crossover other than to make up
for efficiency differences between the high and low
drivers. Taking too much gain or loss in a crossover usual-
ly indicates inappropriate gain structure elsewhere in the
system. For best noise performance, system gain should
be accomplished at the mixer or source Taking gain in
components throughout the system usually yields poor
noise performance. We recommend that a realtime
analyzer or other measurement system be used to set the
relative levels between the low and high outputs. Most
speaker systems can be made relatively flat using only the
level and phase controls on the crossover before equaliza-
tion is applied.
look at the diagram below for a typical application and
consult the Flex User’s Guide.
IMPORTANT NOTE
CHASSIS GROUNDING
Rane Flex Series modules are supplied with a rear-
mounted ground-lift switch. The unit is shipped with
this switch in the “grounded” position, tying circuit
ground to chassis ground. If after hooking up your sys-
tem it exhibits excessive hum or buzzing, there is an
incompatibility in the grounding configuration be-
tween units somewhere. Your mission, should you ac-
cept it, is to discover how your particular system
wants to be grounded. Here are some things to try:
1. Try combinations of lifting grounds on units that
are supplied with ground Lift switches or links.
2. If your equipment is in a rack, verify that all chas-
sis are tied to a good earth ground either through the
the cord grounding pin or the rack screw to another
grounded chassis.
3. Units with outboard power supplies do not
ground the chassis through the line cord. Make sure
that these units are grounded either to another chas-
sis which is earth grounded, or directly to the ground-
ing screw on an AC outlet cover by means of a wire
connected to a screw on the chassis with a star
washer to guarantee proper contact.
Please refer to Rane Note 110 (supplied with your
product and available on request at no charge if you
lost your first one) for further information on system
grounding
PHASE CONTROLS
as well as the polarity switches on
the outputs of the crossover may be adjusted using the
Application Diagram (3, 4-way system)
aforementioned test equipment. Starting with the invert
switches in their “POS” position and the Phase control full
CCW, look at the crossover frequency area with your test
equipment. If you are using pink noise as a source, be
sure to observe only the crossover region. Room acoustics
and imperfect driver response can throw off everything
else to the point of total frustration. Mute the high end
and set the high level control for a 0 dB indication on the
test equipment at the crossover frequency. Now mute the
low and unmute the high. Set the high out for 0 dB at
crossover. Release the mute on the low and you should
see a + MB indication at crossover. If you do not, first try
to achieve it by setting the Phase in-out stitch to the in
position and slowly rotate the phase control clockwise. If
unable to a3 dB at the crossover frequency,
return the phase control to its full CCW position and
change only one of the invert switches to its “IN” position.
again rotate the phase control slowly clockwise. With one
of these combinations you should be able to optimize the
combining of the two drivers.
3-WAY AND BEYOND.
The FAC 24/28 modules may
be combined to produce 3, 4, and 5- way systems. Have a
Copyright 1989, Rane Corporation 10802 47th Ave. W. Mukilteo, WA 98204 (425) 355-6000
520-110 789
