User Manual

Manual-17
CHANNEL TWO:
1. Refer to the board layout on page Schematics-1.
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.
5. The Delay 3 circuit is now removed from all circuits.
6. To install the Delay 3 circuit into the Channel 2, High
Frequency Output, find the jumper W51 behind the
Channel 2 MF MUTE and remove it.
7. Install a long jumper from W42 Pin 1 to W51 Pin 2, and
install a long jumper from W44 Pin 2 to W51 Pin 1.
The Delay 3 circuit is now installed into Channel 2 High
Frequency Output.
STEP BY STEP PROCEUDURE
Transplanting the Mid Frequency Delay to the High
Frequency Output
CHANNEL ONE:
1. Refer to the board layout on page Schematics-1.
2. Behind the Channel 1 MF DELAY pot find the jumper
labeled W26. Behind the Channel 1 MF LEVEL pot find
the jumper labeled W18.
3. To remove the Delay 2 circuit from the Mid Frequency
output, remove both the W26 and W18 jumpers.
4. To get the Mid Frequency output to work again, install a
long jumper from W26 Pin 1 to W18 Pin 2.
5. The Delay 2 circuit is now removed from all circuits.
6. To install the Delay 2 circuit into the Channel 1, High
Frequency output, find the jumper W19 behind the Channel
1 MF MUTE switch and remove it.
7. Install a long jumper from W26 Pin 2 to W19 Pin 1, and
install a long jumper from W18 Pin 1 to W19 Pin 2.
The Delay 2 circuit is now installed into Channel 1 High
Frequency Output.
CHANNEL TWO:
1. Refer to the board layout on page Schematics-1.
2. Behind the Channel 2 MF DELAY pot find the jumper
labeled W55. Behind the Channel 2 MF LEVEL locate the
jumper labeled W50.
3. To remove the Delay 4 circuit from the Mid Frequency
output, remove both the W50 and W55 jumpers.
4. To get the Mid Frequency output to work again, install a
long jumper from W55 Pin 1 to W50 Pin 2.
5. The Delay 4 circuit is now removed from all circuits.
6. To install the Delay 4 circuit into the Channel 2 High
Frequency output, find the jumper W51 behind the Channel
2 MF MUTE switch and remove it.
7. Install a long jumper from W55 Pin 2 to W51 Pin 1, and
install a long jumper from W50 Pin 1 to W51 Pin 2.
The Delay 4 circuit is now installed into Channel 2 High
Frequency Output.
Time Delay Transplant
Modification
There are modification jumpers inside the AC 23B. These
jumpers permit the transplanting of the Delay circuits from
one output to another. As the units are shipped, the Delay
circuit is not installed on the High Frequency outputs. When
the AC 23 was first designed, long throw horns were more
common than Constant Directivity horns (CD horns). The
long throw horn's diaphragm was the farthest sound emitter
from the front of the speaker enclosure, (see Fig. 4) so no
delay was needed. The mid frequency and low frequency
drivers were always in front of the high frequency drivers,
therefore, the mid and low frequency drivers needed the
Delay circuits for proper time alignment.
Now, with the use of CD horns becoming more common,
occasionally there is a need to delay the CD horn as its
diaphragm is usually in front of the other drivers in the
enclosure (see Fig. 5). If you are using CD horns, you should
also read the CD horn EQ modification as described on page
18.With the AC 23 it is a little difficult to figure out which
Delay to move to the High Frequency Output. The normal
configuration for a speaker enclosure is shown in Fig. 3. The
long throw horn’s driver is the farthest back in the enclosure,
so no Delay is needed for this driver. Some Delay is needed
on the Low and Mid drivers. The enclosure with the CD
Horn, shown in Fig. 5, needs the Delay circuit transplanted
from the Low to the High frequencies Outputs. As can be seen
from the dashed line in the drawing, the CD Horn’s driver is
in front of the mid and low drivers. Of the three drivers, the
low frequency driver will need no Delay, the mid frequency
driver will need some Delay, and the CD Horn will need the
most Delay. Soldering is required. This modification should
only be attempted by an experienced technician.
STEP BY STEP PROCEDURE
Transplanting the Low Frequency Delay to the High
Frequency Output.
CHANNEL ONE:
1. Refer to the board assembly layout on page Schematics-1.
2. Behind the Channel 1 LF DELAY pot find the jumper
labeled W8. Behind the Channel 1 LF LEVEL pot find the
jumper labeled W4.
3. To remove the Delay 1 circuit from the Low Frequency
output, remove both the W8 and W4 jumpers.
4. To get the Low Frequency output to work again, install a
long jumper from W8 Pin 1 to W4 Pin 2.
5. The Delay 1 circuit is now removed from all circuits.
6. To install the Delay 1 circuit into the Channel 1 High
Frequency Output, find the jumper W19 behind the
Channel 1 MF MUTE switch and remove it.
7. Install a long jumper from W4 Pin 1 to W19 Pin 2, and
install a long jumper from W8 Pin 2 to W19 Pin 1.
The Delay 1 circuit is now installed into Channel 1 High
Frequency Output.