Logic 3 RAT 1 User Manual
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Speakers & Volume Controls
WHEN USING 8 OHM SPEAKERS
Number of Speaker Pairs Used
S1
S1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
S2
S2
S4
S4
S4
S4
S8
S8
S8
S8
S8
S8
S8
S8
S1
S2
S4
S4
S8
S8
S8
S8
Min. Amp.
Impedance
4 Ohms
8 Ohms
WHEN USING 4 OHM SPEAKERS
Number of Speaker Pairs Used
Min. Amp.
Impedance
S1
S2
1 2 3 4 5 6 7 8
S4
S4
S8
S8
S8
S8
S2
S4
S8
S8
4 Ohms
8 Ohms
SETTING THE IMPEDANCE MATCHING JUMPERS
The impedance matching jumpers are located under a clear mylar cover on the right side of the top of the
unit. Remove the two screws for access. The proper placement of these jumpers depends on the number
of RAT1's and speakers used in the total installation. To set them for the best impedance matching
condition, refer to the following charts and procedures:
Procedure for all 4 Ohm or all 8 Ohm Speakers
1. Determine the rated speaker impedance (refer to the manufacturer's specifications - it must be the
same for all speakers used in the system).
2. Determine the total number of stereo speaker pairs used in the installation.
3. Determine the minimum safe amplifier operating load impedance (refer to the manufacturer's
specifications).
4. Find the correct jumper position from the above charts.
5. Place the jumpers in the same position on each RAT1 used in the system.
Example 1:
13 pairs of 8 Ohm wall speakers are to be used with 13 RAT1's in a 13 room system, all driven by one
amplifier rated for 4 Ohms minimum safe operating load impedance.
1. Refer to the chart "WHEN USING 8 OHM SPEAKERS".
2. Locate the number 13 in the top row.
3. On the next row, opposite "4 OHMS" and just below "13", note the letters "S8". These signify the
required impedance multiplier.
4. The two jumpers therefore, one for each channel, need to be plugged onto the S8 pins on each RAT1
that feeds each room.
Example 2:
3 pairs of 4 Ohm wall speakers are to be used with 3 RAT1's in a 3 room system, all driven by one amplifier
rated for 8 Ohms minimum safe operating load impedance.
1. Refer to the chart "WHEN USING 4 OHM SPEAKERS".
2. Locate the number 3 in the top row.
3. On the third row, opposite "8 OHMS" and just below "3", note the letters "S8". These signify the
required impedance multiplier.
4. The two jumpers therefore, one for each channel, need to be plugged onto the S8 pins on each RAT1
that feeds each room.
RAT1