Altec Lansing 9444B - Manual (Page 4)

Operating and Service Instructions for the Altec Lansing 9444B Power Amplifier
Figure 2 Primary Wiring Configuration for 120 V ac and 220/240 V ac
air temperature exceeds 60 °C
(140 ®F), the equipment should be
spaced at least 1.75 inches apart
or a blower installed to provide
sufficient air movement within
the cabinet.
WARNING: Do not operate the
amplifier within a completely
closed unventilated housing.
S SIGNAL CONNECT­
IONS
3.1 Input Connections
Balanced input connect­
ions may be made to either the
barrier strip or the female XLR
connectors. For single-ended in­
puts, strap the low (—) input to
ground (pin 3 on XLR). Other­
wise, the electronically-balanced
input stage will see 6 dB less in­
put signal level than with a bzJ-
anced input. Refer to Figure 3 for
typical input connections.
3.2 Line Output Connect­
ions
The XLR and barrier strip
connectors are wired in parallel.
Pin 2 of the XLR is the (-f-) input
on the barrier strip, and pin 3 is
the (—) input. Since the input im­
pedance of the electronically-
balanced input stage is high (15
kohms), there is minimal loading
on the signed source. When the
input connections are made to one
connector, the other may be used
as an auxiliary line output to feed
other high input impedance equip­
ment. Refer to Figure 3 for poss­
ible applications.
3.3 Output Connections
Output connections are
made to the four terminal barrier
strip connector located on the rear
of the unit. Refer to Figure 4 for
typical output connections.
3.4 Output Cable Select I<
Speaker wire size pla>^: ft'.
important part in quality so.,
systems. Small wire gauges c.
waste power and reduce the dam­
ping factor at the sp>eaker ter t-
Lnals. Ibis can add coloration a;
muddiness to the sound. To Ы-'г.
offset this problem. Table I r
been assembled to enable yoi;
calculate the power losses in e
speaker cable.
3.4.1 Calculating Powe
Losses with 8 ob^
Loads
To calculate the to
power loss in the speaker cable,
multiply the power loss per Го
(or meter) of the 2-wire cal
selected from Teible I Ьз' и»
length of the cable in feet
meters). For example, suppos. a.
installer uses 160 feet of 10 GA
wire cable with an 8 fl speai •
^stem. Ibe total power loss
the cable is;
Total Power Loss in cable
= 0.0509 watts/foot X 160 feet
= 8.1 watts
Does this mean that whenever
amplifier produces 200 wattr
output power, 191.9 watts (20^
watts minus 8.1 watts) will Ы
delivered to the 8 ohm load? NOI
Tire actual load impedance is
ohms plus the resistance of t
cable (0.00204 ohms/foot thu'
160 feet) for a total load imp
dance of 8.3264 ohms. At the 8 ,
rated output power, the outpu
voltage is 40 V rms. Therefor
the amplifier produces 192.2 watv; .
with this load instead of 2i''.
watts. This was calculated
.squaring the voltage and dividinr
by the load impedance (40^ divl
ed by 8.3264 ohms). As a resui: ,
the actual power delivered to
load is 184.1 watts (192.2 watr
minus 8.1 watts).
ALTEC LANSING* CORPORATION • a Mark IV Company