User Manual

ManualsBrandsRane ManualsAudioAC 23B (1998 version)

Manual-18

Monoing the Low Frequency

Outputs

It is possible to mono the Low Frequency Outputs of the

AC 23B 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 page Schematics-1 and on the

circuit board.

2. Behind the Channel 1 LF LEVEL pot find the jumper

labeled W4. Behind the Channel 1 LF DELAY pot find the

jumper labeled W8.

3. To remove the Delay 1 circuit from the Low Frequency

output, remove both the W4 and W8 jumpers.

4. To get the Low Frequency output to work again, install a

long jumper from W8 Pin 1 to W4 Pin 2.

The Delay 1 circuit is now removed from all circuits.

DELAY THREE REMOVAL

1. Refer to the board layout on page Schematics-1 and on the

circuit board.

2. Behind the Channel 2 LF DELAY pot find the jumper

labeled W44. Behind the Channel 1 LF LEVEL pot find

the jumper labeled W42.

3. To remove the Delay 3 circuit from the Low Frequency

output, remove both the W42 and W44 jumpers.

4. To get the Low Frequency output to work again, install a

long jumper from W44 Pin 1 to W42 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 page Schematics-1 and on the

circuit board.

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 W29.

4. Install a short jumper wire from W29 Pin 1 to W29 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 23B

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 23B

to correct for this high frequency roll off.

STEP BY STEP PROCEDURE

The following 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 23B.

2. Locate the positions for C15 and C16 on page Schematics-

1 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.

3 dB D own

Frequency

Capacitor

2.0 kHz .0015 µf

2.5 kHz .0012 µf

3.0 kHz .001 µf

3.7 kHz 820 pf

4.0 kHz 75 0 pf

5.0 kHz 620 pf

6.4 kHz 470 pf

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