Instruction manual

P82724 E
Sheet 4 of 9
Connect output wires from the speaker load to the COM screw terminal and the selected constant voltage terminal, (i.e. 25V, 70V or
100V). The constant voltage distribution method facilitates the use of multiple speakers in parallel with a single amplifier. Note that
each speaker must have its own 25V or 70V or 100V line-matching transformer. Select the wattage tap on the line matching
transformer of each speaker, for the desired power.
An 8 ohm speaker load may be connected to the COM and the 8 ohm terminal. An 8 ohm speaker or an 8 ohm total speaker load
rated for at least the amplifier's output should be used. (Example: An 8 ohm, 20 watt horn for the AA-20.)
PROPER WIRE SIZE/LENGTH
To minimize power loss in the system cabling, use a wire gauge suitable for the power being distributed and the length of cable. Use
the following table as a guide:
2 WIRE COPPER CABLE LENGTHS FOR SPEAKER LINES AT 0.5dB LOSS IN SPL
(12.5% POWER LOSS IN WATTS)
LOW IMPEDANCE 70 VOLT SPEAKER LINE
SPEAKER LINE NOMINAL POWER IN THE LOAD
AWG
SIZE
4
OHMS
8
OHMS
16
OHMS 5W 10W 15W 30W 50W 100W 200W
AWG
SIZE
10 120 240 480 30,000 15,000 9,900 5,000 3,000 1,500 730 10
12 75 150 300 19,000 9,100 6,200 3,100 1,900 940 460 12
14 50 95 190 12,000 5,600 3,800 1,900 1,200 600 280 14
16 30 60 120 7,500 3,600 2,400 1,200 750 370 180 16
18 20 40 75 4,700 2,300 1,500 750 470 230 ------ 18
20 15 25 50 3,000 1,400 960 480 300 150 ------ 20
22 10 15 30 1,800 900 600 300 190 95 ------ 22
LENGTH IN FEET
NOTES: (1) For 25 volt line divide all 70 volt lengths by 8. (2) For 100 volt line multiply all 70 volt lengths by 1.42. (3) To allow
for future expansion, and distribution cable line loss, it is recommended that the total system wattage should not exceed 85% of the
amplifier's rated output (i.e. 17 watts for the AA-20 and 34 watts for the AA-40). (4) The total system wattage requirement is the
summation of the wattage tap selections of all system speakers and horns.
CAUTION: Per the National Electrical Code, Class 1 wiring should be used for the 100V output. Class 2 wiring is acceptable
for all other outputs.
WARNING: THE COVER FOR THE 100V
AUDIO OUTPUT TERMINAL MUST BE
ATTACHED AT ALL TIMES. THE POWER
CORD MUST BE DISCONNECTED BEFORE
CONNECTING TO THE 100V TERMINAL.
THE COVER MAY BE REMOVED TO
CONNECT A WIRE TO THE TERMINAL,
BUT IT MUST BE REATTACHED AFTER
CONNECTING THE WIRE. FAILURE TO
MAINTAIN THE TERMINAL COVER IN
PLACE COULD EXPOSE YOU AND/OR
OTHERS TO ELECTRICAL SHOCK
WHICH COULD RESULT IN SERIOUS
INJURY OR DEATH.
Output Connections
Figure 3.
Line Output
: (Figure 5)
The LINE OUTPUT jack on the side panel, can be used to cascade amplifiers (including amplified speakers, or Wheelock PRM 150
preamplifiers), or feed audio signal to a tape recorder. The signal on this output is a line level mix of the amplifier's input channels.
Use single conductor shielded cable with a standard RCA type phone plug.