Rane SAC 23 - Manual (Page 7)

Manual-5
Setting Levels With a Realtime Analyzer
1. Set the INPUT LEVEL as described previously on page
Manual-2, and the LOW, MID, and HIGH LEVEL controls
to minimum; leave the FREQUENCY controls as set previ-
ously.
2. Place the analyzer microphone at least 15 feet (5 meters) away
from the speaker stack, on axis (dead ahead) and about chest
level. Minimize any background noise (fans, air conditioners,
traffic, wild animals, etc.) that could affect readings.
3. Run pink noise through the system, either through a mixer
channel or directly into the crossover. Turn all amplifier con-
trols at least half way up.
4. Slowly turn up the LOW LEVEL control until you hear a
healthy level of noise through the low frequency drivers (it
should sound like rumble).
4. Adjust the display controls on the analyzer so that it shows the
greatest number of 0 dB LED’s (green on Rane equipment)
below the crossover frequency.
6. Now slowly turn up the MID LEVEL control until the dis-
play shows the same high frequency output level average as the
low frequency section.
7. Repeat this procedure for all crossover frequency sections, low-
est to highest, so the end result is as flat response as possible
on the analyzer display near each crossover point.
IMPORTANT: Compression driver or horn high frequency
roll-off, bass roll-off, and room acoustics usually cannot be cor-
rected by the crossover.
If, for example, you are adjusting the HIGH LEVEL control
and observe a decline in frequency response somewhat above the
Crossover point, then set the HIGH LEVEL control for equal
display level near the crossover point and leave it there. Use an
equalizer to correct the roll-off problem.
If you are tuning the system in a room, the acoustics will
greatly influence the system response, as shown by the analyzer.
Move the microphone and check the analyzer system re-
sponse at several other locations. Adjust the crossover to reach
a fixed compromise setting as necessary. If you plan to use the
analyzer only once to set the crossover, set up the speaker system
in a quiet place outside or in a very large concert theater, and
run pink noise at low levels with closer microphone placement
to keep the room acoustics out of the picture as much as possible.
Setting Levels With an SPL Meter & Pink Noise Generator
1. Run pink noise into the crossover Inputs (through the mixer
or directly, as is convenient).
2. Make sure all crossover LEVEL(s) are turned all the way down
and all amplifier level controls are at least half way up to start
with.
3. Turn the crossover INPUT LEVEL all the way up. Place the
SPL meter at least 15 feet from the speaker stack and about
chest high. Once positioned, make sure that the SPL meter re-
mains in the exact same location for the rest of the procedure.
Minimize all background noise (fans, air conditioners, traffic,
wild animals, etc.) to get accurate readings. Set the SPL meter
to “C-weighting” and “slow” if those switches are present.
4. Slowly turn the LOW LEVEL up until there is a healthy
rumble coming from the bass speakers. Adjust the SPL meter
and/or LOW LEVEL until you get a 0 dB reading on the me-
ter. After this point do not change the controls on the SPL meter.
5. Make a note of the LOW LEVEL control setting at the 0 dB
adjustment just obtained, then reduce the LOW LEVEL to
“0” so that the pink noise disappears from the bass speakers
(revel in the silence...).
6. Now slowly turn up the MID LEVEL control so that pink
noise is heard from the high frequency speakers. Without
changing any settings on the SPL meter, adjust the crossover
MID LEVEL control until you obtain a 0 dB reading on the
SPL meter.
7. Turn down the MID LEVEL and repeat this process for the
HIGH LEVEL. Return the LOW and MID LEVELS to the
previously recorded settings. Now all drivers are set at the
same level. Make any overall level adjustments with the IN-
PUT LEVEL controls and leave the output LOW, MID and
HIGH LEVEL controls unchanged.
It is possible to turn one of the frequency section output LEVEL
controls all the way up and still not have enough volume for a
0 dB reading (as determined by previous section levels). This
is probably due to different sensitivities of amps, speakers and
other level controls in the system. When this happens, re-set the
SPL meter so that it reads 0 dB on this frequency section (you
may have to “down range” the meter and re-adjust the crossover
INPUT LEVEL control). Now go back and re-adjust the previ-
ous crossover LEVEL controls, turning these down to get a 0 dB
reading on the meter.