Rane FAC 28 User Manual
OPERATING / SERVICE MANUAL FAC 28
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 manufacturer. 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.
ACTIVE CROSSOVER
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 character 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 unbalanced 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 applications, mid and high are taken from
the LOW and HIGH OUTS of the
second module, respectively. If a
four way system is being constructed, 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 impervious to corrosion and stresses of time and environment.
FRONT PANEL DESCRIPTION
1. INPUT OVERLOAD INDICATOR. This red LED will illuminate any time the
input stage is driven to within 4dB of clipping. This level is a function of both
input signal level and the position of the input gain control.
2. INPUT LEVEL CONTROL This rotary control determines the input gain of
the crossover. Its range is from -20dB to +6dB. The majority of applications
should find this control set at 0dB for unity gain.
3. HIGH OUTPUT OVERLOAD INDICATOR. This red LED will illuminate
anytime the high frequency output of the crossover is driven to within 4dB of
clipping. This level is a function of both the INPUT level and the HIGH frequency output LEVEL control.
4. HIGH OUTPUT LEVEL CONTROL. This rotary control determines the
amount of gain to follow the high frequency output of the crossover’s frequency
dividing network. Its range covers OFF to +6dB.
5. HIGH FREQUENCY INVERT SWITCH. This two position slide switch
electrically inverts the high output in the INV position. This may be necessary
where drivers or amplifiers are wired incorrectly or when the crossover’s phase
control lacks sufficient range (more that 180 degrees becomes necessary).
6. HIGH FREQUENCY MUTE SWITCH. In its in position, all output signal
from the High Output of the crossover will be totally muted. This is to be used
when initially setting Levels of the Low Output and during the Phase alignment
process.
7. HORN EQ DEFEAT SWITCH. If a constant-directivity horn is to used on the
High Output, set this switch to the IN position.
8. HORN EQ FREQUENCY CONTROL. This rotary control allows a continu-
ously variable adjustment of the frequency at which boost begins to occur. This
should be set based on the horn manufacturer’s recommendation.
9. CROSSOVER FREQUENCY SELECTOR. This rotary control offers 24
precise frequencies at which the crossover makes the divide between the High
and Low Outputs. It is a binary encoding switch which sets up the digital control
of the filter’s frequency dividing circuits for very high precision.
10. PHASE CONTROL BYPASS SWITCH. In its OUT position, the phase
control has no effect on the low frequency output.
11. PHASE ANGLE CONTROL. This rotary control provides a constantly
variable 0 to 180 degree phase shift between the Low and High Outputs.
12. LOW FREQUENCY OVERLOAD INDICATOR This red LED illuminates
any time the Low Output comes within 4dB of clipping. This level is a function
of INPUT level as well as LOW frequency Output LEVEL.
13. LOW FREQUENCY LEVEL CONTROL. This rotary control varies the
output gain of the LOW frequency section from OFF to +6dB.
14. LOW FREQUENCY INVERT SWITCH. This switch electrically inverts the
polarity of the low output in the INV position. This may be necessary for many
of the same reasons cited in #5, above.
15. LOW FREQUENCY MUTE SWITCH. Identical to #6 above, with the
exception that it Mutes the Low Output.
16. POWER INDICATOR Illuminates whenever the correct AC power is applied
to the unit from a remote power supply.
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