Altec Lansing 9444B User Manual

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9444B and 9444B/SA

Anniversary Series Power Amplifier

Operating and Service Instructions

ALTEC LANSING® CORPORATION

u MARK rV company

P. O. Box 26105 • Oklahoma City. OK e 73126-0105 USA ® Tel: [phone] • FAX: [phone]

Operating and Service Instructions for the Altec Lansing 9444B Power Amplifier

Table of Contents

1 ELECTRICAL.................................................................................................................................................

1.1 120 V ac, 50/60 Hz Power Connections......................................................................................................

1.2 220/240 V ac, 50/60 Hz Power Connections...............................................................................................

2 INSTALLATION............................................................................................................................................

2.1 Rack Mounting ...........................................................................................................................................

2.2 Ventilation ...................................................................................................................................................

3 SIGNAL CONNECTIONS................................................................................................................................. -

3.1 Input Connections ...........................................................................................................................................-

3.2 Line Outpxrt Connections...........................................................................................................................

3.3 Output Connections........................................................................................................................................ 2

3.4 Output Cable Selection................................................................................................................................... -

3.4.1 Calculating Power Losses with 8 ohm Loads......................................................................................

3.4.2 Calculating Power Losses with 4 ohm Loads

3.0 Damping Factor...........................................................................................................................................

3.5.1 Calculating the Maximum Length of Cable for a Specified Damping Factor

3.6 Speaker Protection Fuse Selection..............................................................................................................

3.7 Compression Driver Protection Capacitors ................................................................................................

......................................................................................

.....................................

3

• i

4 OCTAL ACCESSORY SOCKETS..................................................................................................................... 5

5 PROTECTION SYSTEMS ............................................................................................................................

5.1 Load Protection Circuitry............................................................................................................................

5.2 Amplifier Protection Circuitry ....................................................................................................................

5.3 Protect Indicator...........................................................................................................................................

6 OPERATION..................................................................................................................................................

6.1 Dual Mode of Operation....................................................................................................................................

6.2 Bridge Mode of Operation .............................................................................................................................. P

7 IN CASE OF PROBLEMS .............................................................................................................................

8 SPECIFICATION................................................................................................................................................ S

9 SERVICE INFORMATION........................................................................................................................... L2

9.1 Trimpot Adjustments.......................................................................................................................................2

9.2 Equipment Needed........................................................................................................................................ ;2

9.3 Adjusting R39, the LF Cancel Trimpot.......................................................................................................

9.4 Adjusting R26, the BIAS Trimpot................................................................................................................... ù

9.5 Adjusting R23 and R24, the Negative and Positive Current Limit Trimpots.............................................. 3

9.6 Checking the Short Circuit Current ............................................................................................................ . ^

9.7 Ordering Replacement Parts .......................................................................................................................

9.8 Factory Service

9.9 Technical Assistance ..................................................................................................................................

...

.......................................................................................................................................

.

10 THE 9444B/SA ..............................................................................................................................................

ALTEC LANSING^ CORPORATION • a Mark TV Company

Operating and Service Instructions for the Altec Lancing 9444B Power Amplifier

1 ELECTRICAL

Two amplifier models are
available. One model has a 50/60
Hz power transformer with two

120 V ac primary windings. These
windings may be wired in parallel
or series for operation at either

120 V ac or 220/240 V ac. The ot
her amplifier model is for export
into countries where the ac line
voltage is 100 volts, 50/60 Hz. The

next two sections refer to the first

model with the dual 120 V ac pri

mary windings.

1.1 120 V ac, 50/60 Hz
Power Connections
The amplifier is provided

with the primary of the power tra

nsformer strapped for 120 V ac
operation from the factory. Refer
to Figure 2a for the wiring details.

WARNING: Verify that the power

transformer’s primary circuit
configuration is correct for the
intended ac line voltage BEFORE
applying power to the amplifier.

1.2 220/240 V ac, 50/60 Hz
Power Connections
The power transformer

has two 120 volt primary windings

which can be connected in paraDel
for 120 V ac line voltages, or in
series to meet 220/240 V ac requi

rements. Use the following pro
cedures to re-strap the primary of
the power transformer for 220/240
V ac applications.

1. Make sure the amplifier is
not connected to any po
wer source.

2. Remove and save the ele
ven screws securing the
top cover. There are three
screws on each side and
three along the top-rear
edge of the chassis. In
addition, you must remove
the two iimermost screws
inset into the top bumper
strip. Refer to Figure 1 for
the exact screw locations.

Figure 1 Top Cover Removal

3. Locate terminal blocks
TBl and TB2 on the side
of the chassis near the
rear input PC board. Re
connect the leads as
shown in Figure 2b.

4. Install the top cover with
the eleven screws previ

ously removed. Two scr
ews г!ге longer than the
others removed from the
sides and rear. These

longer screws install into
the reeirmost position on

each side of the chassis.

5. Install an 5A fuse, Littel-

fuse Type ЗАВ 5A/250V
slo-blo 326-series ceramic
body or equiv.

2 INSTALLATION

2.1 Rack Mounting

The amplifier ’nay be in
stalled in a standard 19 inch
equipment rack. It :■ .niires 5V4
inches of vertical rack fipace and
secures to the rack -iibinet with
the four rack mount screws emd
cup washers provided ui the hard
ware kit.

2.2 Ventilation

The amplifier must be ad
equately ventilateo ' e, avoid ex
cessive temperatur- r- ^. It should
not be used in area.' where the
ambient temperature '.xceeds 60
°C (140 °F). To determine the am
bient air tempera: i. : r, operate the
system in the rack until the temp
erature stabilizes. Measure the
ambient air with a bull.-type ther
mometer held at tlie Dottom of the
uppermost amplifier Do not let
the thermometer torich the metal

chassis because the chassis will be
hotter than the ambjent air. If the

ALTEC LANSING* CORPORATION • a Mark IV Company

Operating and Service Instructions for the Altec Lansing 9444B Power Amplifier

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

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 bzJ­anced 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 electronically­balanced 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

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
minus 8.1 watts).

184.1 watts (192.2 watr

ALTEC LANSING* CORPORATION • a Mark IV Company