Manual-12
8. Repeat this process for each frequency section of the
crossover, ending with the highest frequency. NOTE: It is
possible that you may turn one of the frequency section
output LEVEL controls all the way up and still not have
enough volume for a 0dB 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 0dB on this frequency section (you may have to
“down range” the meter and re-adjust the crossover
LEVEL control). Now go back and re-adjust the previous
crossover LEVEL controls, turning these down to get a 0dB
reading on the meter.
9. Once the HIGH LEVEL control is set for 0dB on the meter,
disengage all of the MUTE switches on the crossover, and
check that noise is emitting from all the speaker compo-
nents. The crossover should now be aligned. Make any
overall level adjustments with the input MASTER LEVEL
controls and leave the output level controls unchanged.
Setting Levels Using an SPL
Meter & Pink Noise Generator
The MUTE switches on the AC 22 make using an SPL
meter an easy and relatively accurate means of tuning a
system. First, obtain a good SPL meter from a local electron-
ics store. Second, and perhaps a little trickier, get a hold of a
pink noise generator—again try electronics stores. You may
also use a sweep or tone generator in place of a pink noise
source. If so, be sure to look at several different tones within
each crossover section to get a good average driver response.
1. Run pink noise into the crossover inputs (through the mixer
or directly, as is convenient).
2. Make sure all crossover output LEVELs 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(s) half 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
remains 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, Slow” if
those switches are present.
4. Slowly turn the LOW LEVEL of the crossover up until
there is a healthy rumble coming from the bass speakers
(For this example the 3-way configuration is used—the
same procedure applies to all configurations, starting with
the lowest frequency and ending with the highest). Adjust
the SPL meter and/or crossover output until you get a 0dB
reading on the meter. After this point do not change the
controls on the SPL meter.
5. While leaving the LOW LEVELcontrol at the 0dB adjust-
ment just obtained, press the LOW MUTE switch on the
crossover 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 mid frequency speakers. Without
changing any settings on the SPL meter, adjust the cross-
over MID LEVEL control until you obtain a 0dB reading
on the SPL meter. Now the low and mid speakers are set at
the same level.
7. Now press the MID MUTE switch on the crossover so that
the pink noise again disappears.
Fig. 5 Configuration with Constant Directivity Horn
Fig. 4 Normal Configuration with Long Throw Horn
