Manual-18
Monoing the Low Frequency
Outputs
It is now possible to mono the Low Frequency Outputs of
the AC 23 by an internal jumper modification. This requires
that the Delay 1 and Delay 3 circuits be removed from the
signal path, and that R33 be removed. The following proce-
dure will assist you through the modification. Soldering is
required. This modification should only be attempted by an
experienced technician.
DELAY ONE REMOVAL:
1. Refer to the board layout on the back page.
2. Behind the Channel 1 LF DELAY pot find the jumper
labeled W6. Behind the Channel 1 LF LEVEL pot find the
jumper labeled W3.
3. To remove the Delay 1 circuit from the Low Frequency
output, remove both the W6 and W3 jumpers.
4. To get the Low Frequency output to work again, install a
long jumper from W6 Pin 1 to W3 Pin 2.
The Delay 1 circuit is now removed from all circuits.
DELAY THREE REMOVAL:
1. Refer to the board layout on the back page.
2. Behind the Channel 2 LF DELAY pot find the jumper
labeled W28. Behind the Channel 1 LF LEVEL pot find
the jumper labeled W22.
3. To remove the Delay 3 circuit from the Low Frequency
output, remove both the W28 and W22 jumpers.
4. To get the Low Frequency output to work again, install a
long jumper from W28 Pin 1 to W22 Pin 2.
The Delay 3 circuit is now removed from all circuits.
REMOVING R33 AND SUMMING THE LOW FRE-
QUENCY OUTPUTS:
1. Refer to the board layout on the back page.
2. Behind the Channel 2 LF LEVEL pot find the resistor R33,
and remove it, in any way your heart desires, though
violence will void your warranty.
3. Behind the Channel 1 HF LEVEL pot find the jumper
W15.
4. Install a short jumper wire from W15, Pin 1 to W15, Pin 2.
Solder in place.
The Low Frequency Outputs are now summed.
Constant Directivity Horn
Equalization Modification
Constant Directivity (or CD) horns need additional
equalization to help cover the same area a long throw horn
can cover. Additional circuitry has been added to the AC 23
for the additional equalization of the High Frequency outputs
for the CD Horns. This modification should only be attempted
by an experienced technician.
It is important to know the 3 dB down point of the CD
driver's frequency response. The manufacturer of your driver
should be able to supply you with a chart showing a fre-
quency response curve. Find the point where the high end
starts to roll off, and look for the point on the chart that is 3
dB down from that point (toward the right, as the higher
frequencies roll off). Find the frequency at the bottom of the
chart of this point—an approximate is fine, you don't have to
be exact. Find the closest frequency in the table below to
determine the correct value capacitor to install in the AC 23
to correct for this high frequency roll off.
STEP BY STEP PROCEDURE
This procedure is for CD horn EQ on the High output in
Stereo 3-Way mode. For a Mono 4- or 5-Way system with a
CD horn on the high output, only place C16 in Channel 2.
1. Remove the top and bottom covers of the AC 23.
2. Locate the positions for C15 and C16 on page S1 and on
the circuit board. C15 (for Channel 1) is located behind the
CH 1 MF MUTE switch. C16 (for Channel 2) is located
behind the CH 2 MF MUTE switch.
3. Clean the solder pad on the underside of the board so that
the appropriate capacitor can be inserted. Install the
capacitor, and solder the leads from the underside using
fresh solder. Clip the excess leads.
4. Replace the top and bottom covers.
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com
3 dB Down
Frequency
Capacitor
2.2 kHz
.0027 µf
2.5 kHz
.0024 µf
2.7 kHz
.0022 µf
3.3 kHz
.0018 µf
4.0 kHz
.0015 µf
5.0 kHz
.0012 µf
6.0 kHz
.001 µf
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