Manual-8
6. RA 30 setup:
a. Place the RA 30 CAL MIC on axis, 1 meter away from
the Low driver as shown in Figure 5, Position 1.
b. Set the RA 30 SOURCE to CAL MIC.
c. Set the RA 30 to SPL mode.
d. Set the RA 30 SPL Filter to C-WEIGHT.
e. Turn on the RA 30 PINK NOISE.
7. Make sure the Pink Noise Level coming into the crossover is
able to light the red OL indicator.
8. Set SPL
MAX
for each driver (one Output at a time):
a. Depending on the maximum safe SPL rating of your
system, you may want to use ear protection.
b. Place the CAL MIC on axis at 1 meter (see Figure 5).
c.
Un
MUTE the AC 24 Output associated with the driver
you are setting the Limiter for.
d. Slowly increase the LIMIT Threshold until the RA 30
SPL meter reads the SPL
MAX
calculated in step 4 for the
driver you are setting the Limiter for.
e. MUTE the associated AC 24 Output.
f. Repeat for each driver.
Method Two: Voltage at the driver.
Method Two uses the voltage at the driver instead of the SPL.
Using voltage is not as desirable as SPL because impedance often
varies with frequencies. Manufacturers provide the maximum
recommended continuous power (P) and Nominal Impedance
(R) ratings for each Driver. The maximum voltage is calculated
as follows:
• V
MAX
= √(P*R)
P = Maximum Power
R = Nominal Impedance
• Calculate V
MAX
for each driver.
• Follow the steps outlined above for setting Limiters using
SPL. Simply substitute volt meter readings for RA 30 SPL
readings.
System calibration is complete!
We highly recommend installing the included security
cover As Soon As Possible!
Fix-lt-With-The-Crossover School
Consider the following (now that you have worked so hard to
accurately set up the crossover). Some maintain that a good ac-
tive crossover can work alone like a parametric equalizer in the
hands of an expert. This does require experience, skill, and the
right equipment to back it up (not to mention a licensed set of
ears). Regardless of which school you profess, the absolute impor-
tance and effectiveness of some kind of realtime analyzer in your
system cannot be overstressed! Analyzers in general have come
a long way. An analyzer saves tremendous amounts of time and
provide the absolute consistency, accuracy, and plain old good
sound that few ears on this earth can deliver. You’ll wonder how
you managed without one.
39.4"
POSITION 4
POSITION 1
POSITION 2
POSITION 3
(1 meter)
mic
mic
mic
mic
Figure 5. Setting Output Levels with a calibrated mic.
STEP FIVE: Setting Limiters
Each AC 24 Crossover Output has a Limiter. Each Limiter has
an independent Threshold control with a range of 0 dB FS to
–64 dB FS. To maintain spectral accuracy, Mid, Hi-Mid and
High Limiters are linked. Linking is accomplished with wired-or
control. These outputs all receive the same gain reduction regard-
less of which one initiates limiting. Independent Threshold indi-
cators show which band is the source of the limit condition. The
Low Output Limiter may operate independently. This is often
desirable to prevent “pumping” or modulating higher frequen-
cies. If desired, there is a Low Limit Link switch.
Method One: Driver SPL.
1. Do
not
change any of the previously calibrated AC 24 Output
Level controls.
2. Do
not
change any amplifier gain controls.
3. MUTE all AC 24 Outputs.
4. Set all LIMIT controls to –64.
5. Determine the maximum SPL for each driver.
a. Find the manufacturers sensitivity rating
(dB SPL @ 1 watt, @ 1 meter ) = dB SPL
REF
b. Find the manufacturers maximum continuous power
rating (P
MAX
)
c. SPL
MAX
= dB SPL
REF
+ [10*Log(P
MAX
)]
106220
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 USA TEL 425-355-6000 FAX 425-347-7757 WEB www.rane.com
