REAR PANEL DESCRIPTION
1. l/4" INPUT CONNECTOR
A balanced/unbalanced input, the tip is positive, ring is negative
and sleeve is ground. For unbalanced operation, drive. the tip as hot and the sleeve as ground.
You may use a TRS or “mono” connector. If the former is used, the ring may be left open or
shorted to sleeve.
2. 3-PIN INPUT CONNECTOR
Pin 2 is positive, pin 3 is negative and pin 1 is signal ground.
For unbalanced operation, drive pin 2 as hot and 1 as ground.
3. 1/4" HIGH FREQUENCY OUTPUT CONNECTOR
This l/4" TRS connector parallels the
3-pin connector featured in item #4. Tip is positive, Ring is negative and Sleeve is signal ground
4. 3-PIN HIGH FREQUENCY OUTPUT CONNECTOR.
Pin 2 is positive, pin 3 is negative and
pin 1 is signal ground. For unbalanced operation, DO NOT SHORT ANY PINS TO ANY
OTHERS. Active balanced outputs operated in the unbalanced mode should only consist of pin
2 driving the line and pin 1 acting as the return. Pin 3 should be left disconnected.
5. 1/4" LOW FREQUENCY OUTPUT CONNECTOR
This l/4" TRS connector parallels the
pin connector featured in item #6. Tip is positive, Ring is negative and Sleeve is signal ground.
6. 3-PIN LOW FREQUENCY OUTPUT CONNECTOR.
Identical to item #4 above except this
one sings the low parts.
7. Low SUM INPUT CONNECTOR
This unbalanced input consists of only a tip and
sleeve contact. The tip is positive and the sleeve is ground. It is to be used to connect the low fre-
quency output of another crossover module so that the Low Out of the driven unit consists of a
mono sum of both low frequency sections. This is useful for mono sub woofer applications in a
two channel (dare we we the word stereo) system.
8. GROUND LIFT SWITCH.
This switch provides the ability to separate chassis ground and
signal ground. Normally, this switch should be in the LIFT position. In some circumstances it
maybe necessary to move it to the opposite position to elite stubborn hum and buzz
problems. We realize a scientific explanation of this switch would be helpful, unfortunately
science doesn’t seem to have much to do with it.
If you are tempted to try moving this switch with your power amplifiers turned on or turned up,
DON’T BE. ALWAYS TURN YOUR AMPLIFIER LEVELS DOWN BEFORE CHANG-
ING YOUR GROUNDS AROUND and then bring them up slowly.
9. REMOTE POWER SUPPLY INPUT.
The FAC 24/28's are supplied from the factory with a
Model RS 1 Remote Power Supply suitable for connection to this input jack. The power require-
meats of the FAC 24/28 call for a 18-24 volt AC center-tapped transformer only. THIS IS NOT
A DC INPUT. IT IS NOT A TELEPHONE JACK.
NEVER USE A POWER SUPPLY WITH YOUR CROSSOVER OTHER THAN THE
ONE SUPPLIED OR AN EXACT REPLACEMENT OBTAINED FROM RANE COR-
PORATION. Using any other type of supply may damage the unit and void the warranty. Two
years parts and labor is worth safeguarding, don’t you think?
10. EXTERNAL GROUND ATTACH POINT.
This threaded hole is to be used to attach an external earth ground to the
system. This may be necessary in situations where no other earth ground reaches the chassis of the processing components
due to the fact that the third pin earth ground of the line cord does not pass through the external power supply. If the rack
rails are not earth grounded by some other means, one of the FLEX components in your system may require that this con-
nection be made for safety purposes and noise performance.
OPERATING INSTRUCTIONS
Before attempting a complete run-down of operating
crossover. The fourth order version exhibits rolloffs of 24 dB
guidelines for the FAC crossovers, a few words about state-
per octate the FAC 28 a steeper 48 dB per octave. In both
variable Linkwitz-Riley filters are in order. Rane imple-
cases, at the crossover frequency the high and low outputs
meats this alignment using two cascaded two pole
are 6 dB down from unity and in phase. with each other. The
butterworth filters in the FAC 24 to produce the fourth
result is a combined output which is completely flat from
order characteristic. The FAC 28 simply multiplies the cir-
one end of the audio spectrum to the other. See Rane Note
cuitry of the FAC 24 times two and produces an 8th-order
119 for greater detail. The important element here is that
