Rane FAC 28 - Manual

OPERATING / SERVICE MANUAL FAC 28
ACTIVE CROSSOVER
QUICK START
No one likes to read manuals. Everyone likes to plug in and turn on. That’s usually OK,
and with only a very few exceptions, damage is unlikely to result from such procedures when
initiating the use of a FAC 28.
It is a good idea to begin with all LEVEL controls set to their full counterclockwise
position. Unless you are certain that there is an electrical inversion in one of your amplifiers or
drivers, set both POS INV switches to their POS positions. Both MUTE switches should be
out. If you are using a constant-directivity horn, set the HORN EQ IN/OUT switch to the IN
position and adjust the frequency control per the recommendations of the horn’s manufac-
turer. Set the PHASE IN/OUT switch to the OUT position. Set the crossover FREQ selector
to the frequency recommended by the speaker manufacturer. Power up the system and set the
input and output levels for appropriate performance.
NEVER CONNECT ANYTHING EXCEPT AN APPROVED RANE POWER
SUPPLY TO THE THING THAT LOOKS LIKE A TELEPHONE JACK ON THE
REAR OF THE FAC 28. This is an AC input and requires special attention if you do not
have an operational power supply EXACTLY like the one that was originally packed with
your unit. See the full explanation of the power supply requirements elsewhere in this manual.
SYSTEM CONNECTION
When connecting the FAC 28 to other components in your
system for the first time, leave the power supply for last. This
will give you a chance to make mistakes and correct them
before any damage is done to your fragile speakers, ears and
nerves.
INPUTS on the FAC 28 are balanced. The 3-pin (XLR)
uses pin 2 as “hot” or “+” signal polarity, pin 3 is “return” or
“–” and pin 1 is signal ground. If unbalanced operation is
required, drive pin 2 as hot and pin 1 as ground. The ¼" Input
is a tip-ring-sleeve connector. Tip is “+”, ring is “–”, and
sleeve is ground. Unbalanced ¼" inputs should drive tip as
hot and sleeve as ground and may be either a “mono” ¼" or
TRS ¼" with the ring left open or tied to sleeve, your choice.
See Rane Note 110 for further information on this subject.
OUTPUTS. The FAC 28’s Outputs are balanced as well.
As with the 3-pin Input, pin 2 is hot and pin 3 is not. Pin 1 is
signal ground. True balanced operation requires only the use
of pins 2 and 3 for signal and either case ground (chassis) or
pin 1 signal ground for shielding. If unbalanced output is your
preference, use pin 2 as signal and pin 1 as return. Use case
ground for shield. The ¼" Output is a tip-ring-sleeve charac-
ter whose polarities match the Input connector. Again, have a
look at Rane Note 110 for more detail.
THE LOW SUM INPUT is used to combine the Low
frequency Outputs of two crossover modules (mono sub bass
in stereo applications). To take advantage of this feature, the
LOW OUT of one crossover module connects to this unbal-
anced Input. The sum of both modules low frequency
selections then appears at the LOW OUT of the module
whose LOW SUM INPUT is being driven.
3-WAY, 4-WAY etc . Two or
more FAC crossovers may be used
together to produce 3, 4 and 5-way
systems. To accomplish this, the
first unit is driven with full range
audio. The sub bass output is taken
from the LOW OUT of the first
module, the HIGH OUT of the first
module then drives the main INPUT
of the second. For 3-way applica-
tions, mid and high are taken from
the LOW and HIGH OUTS of the
second module, respectively. If a
four way system is being con-
structed, the HIGH OUT of the second module drives the
third, the LOW OUT of the second module becomes the
low-mid, the LOW OUT of the third module is the 3rd
frequency range, the HIGH OUT of the third module becomes
the 4th. See the diagram on the back page of this document as
well as the Flex User’s Guide for more details.
CHOICES need to be made regarding which Input and
Output connectors to use. Generally, the ¼" ins and outs work
well enough and are definitely cheaper to use in terms of
labor and material required to terminate cables with ¼" plugs.
The 3-pins do, however, provide a locking mechanism for
situations where physical abuse can be a problem. The 3-pin
also provides a tighter connection and can be more impervi-
ous to corrosion and stresses of time and environment.