Rane AC 22, Operating And Service Manual

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lower frequency driver to electronically move backward until the S PL meter reads +3 dB; then
the two drivers are electronically aligned and the on-axis cancellation is eliminated. This
procedure is then repeated for the next lower crossover point(s).
STEP BY STEP PROCEDURE:*
1. Set the tone generator to the highest crossover frequency and plug it into the input of the
crossover. Turn all crossover level controls fully down.
2. Position the SPL meter (microphone) about 15 feet in front of the speakers and at a height
about midway between the Hi and Mid drivers. It is very important that the meter remain in
exactly the same position throughout the test so affix it to a mic stand, small tree or other
stable object
3. Slowly turn up both the crossover input control and the Mid frequency level control until
the tone is heard through the Mid driver. Adjust the SPL meter control and/or the crossover
level controls until you obtain a OdB reading on the meter. Verify that no sound is coming from
any other speakers except the Mid driver.
4. Now press in the Mid frequency Mute switch on the crossover so that the tone is removed
from the Mid driver. Without re-adjusting either the meter or the crossover input or Mid
frequency level controls, turn up the Hi level control until the tone coming from only the Hi
driver reads OdB on the SPL meter.
*A three-way mode consisting of Hi, Mid and Low drivers is used as an example in this
procedure. For other configurations, use the same procedure starting with the highest
crossover point and repeating steps 2 through 5 for each lower crossover point.
5. Now release the Mid Mute switch so that the tone is emitted from BOTH the Hi and Mid
drivers. Check the reading on the SPL meter:
A If the meter reads +3 dB, then
· the drivers are properly phase aligned and no delay is
necessary; leave the Mid delay control at full minimum.
8. If the meter reads LESS THAN +J dB, slowly turn up the Mid frequency delay control
until the meter just read:. +-3 dB. Now the drivers are electronically phase aligned and the delay
control should be left in this position at all times, unless the speaker system is physically
altered.
C. If you have turned the Mid Delay control all the way up and still do not obtain a +3dB
reading, you will have to physically move the Hi driver farther forward until the S PL meter reads
+JdB. The amount of displacement corrections available from the delay depends on the
actual crossover frequency: the higher the frequency the less amount of correction capability.
Refer to Diagram 111-3. If the drivers are built into a single cabinet and/or it is impossible to
change relative positions, then you will have to obtain additional delay to achieve proper
phase alignment. Rane' s Model CD 48 Delay Console or other delay source should be used -­
consult your local dealer.
0. If turning the Mid delay control up makes the SPL reading DECREASE instead of
increase, this means that the Hi driver is actually IN FRONT of the Mid driver; adding delay to
the Mid driver then only worsens the situation. There are a couple of ways to deal with this:
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