Altec Lansing 9441A User Manual
^ ■ \
9441A
Anniversary Series Power Amplifier
O pe r at i ng an d S e rv i ce In s tr u ct i on s
ALTEC LANSING® CORPORATION
n MARK IV coiiipiiiiy
P. O. Box 26105 © Oklahoma City, OK • 73126-0105 USA © Tel: (405) 324-5311 © FAX: (405) 324-89b1
Operating and Service Instructions for the Altec Lansing 9441A Power Amplifier
Table of Contents
1 ELECTRICAL
1.1 120 V ac, 50/60 Hz Power Connection.«;........................................................................................... 1
1.2 220/240 V ac, 50/60 Hz Power Connections....................................................................................... 1
2 INSTALLATION.................................................................................................................................... 1
2.1 Eack Mounting .................................................................................................................................. 1
2.2 Ventilation ............................................................................................................................ . 1
3 SIGNAL CONNECTIONS...................................................................................................................... 2
3.1 Input Connections ............................................................................................................................. 2
3.2 Line Output Connections.................................................................................................................... 2
3.3 Output Connections........................................................................................................................... 2
3.4 Output Cable Selection....................................................................................................................... 2
3.4.1 Calculating Power Los.ses with 8 ohm Loads
3.4.2 Calculating Power Losses with 4 ohm Loads................................................................................. 2
3.5 Damping Factor.......................................................................................................................... . 2
3.5.1 Calculating the Maximum Length of Cable for a Specified Damping Factor
3.C Speaker Protection Fuse Selection ...................................................................................................... 5
3.7 Compros.sion Driver Protection Capacitors ........................................................................................... 5
4 OCTAL ACCESSORY SOCKETS
5 PROTECTION SYSTEMS .............................................................................................................. . . 5
5.1 Load Protection Circuitry..................................................................................................................... 5
5.2 Amplifier Protection Circuitry ............................................................................................................... 5
5.3 Protect Indicator........................................................................................................................ . . 6
......................................................................... ...........................................................
..................................................................................
...............................
. 3
‘ 1
2
G OPERATION......................................................................................................................................... 6
G.l Dual Mode of Operation............................................................................................................... . . 6
G.2 Bridge Mode of Operation ................................................................................................................... 6
7 IN CASE OF PROBLEMS
8 SPECIFICATION
9 SERVICE INFORMATION.................................................................................................................. 10
9.1 Equipment Needed......................................................................................................................... 11
9.2 Adjusting SVRl and SVR2, the BIAS Trimpots
9.3 Ordering Replacement Parts ..............................
9.4 Factory Service
9.5 Technical Assistance .........................................
...................
................................................
6
7
11
11
11
11
ALTEC JJCStSING^ CORPORATION o a Mar-k W Company
Operating and Service Instructions for the Altec Lansing 9441A 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
other amplifier model is for export
into countries where tlie ac line
voltage is 100 volts, 50/60 Hz. The
next two sections refer to the first
model witli the dual 120 V ac pri
mary windings.
1.1 120 V ac, 50/60 Hz
Power Coimections
'rhe amplifier is provided
with the primary of the power
transformer slrappcil for 120 V ac
operation from the factory. Refer
to Figure 2 for the wirijjg deUiils.
WARNING: Verify that the power
transformer’s priinaiy circuit con
figuration is correct for the in
tended 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 parallel
for 120 V ac line voltages, or in
series to meet 220/240 V ac re
quirements. Use the following
procetlures to re-strap the primary
of the power transformer for
220/240 V ac applications.
1. Malce sure the amplifier is
not connected to any
power source.
2. Remove and save the ten
screws securing the top
cover. Refer to Figure 1
for the exact screw loca
tions.
3. Locate terminal block TBl
located behind the AC
main power switch. Re
connect the leads as
shown in Figure 2.
4.
Install the top cover with
the ten screws previously
romovetl.
5.
Install the 2.0 A fuse,
T2.0A /250V slo-blo or
equivalent.
6.
Install the 230 Vac 50/-
60Hz and the T2.0A/250V
decals in the proper
positions.
INSTALLATION
2.1
Rack Mounting
The amplifier may be in
stalled in a standard 19 inch
equipment rack. It requires 1.75
inches of vortical rack space and
secures to the rack cabinet with
the-four rack mount screws and
cup washers provided in the hard
ware kit.
2.2 Ventilation
The amplifier m.;;;t be
adequately vontil.ntod tn ir.'oid ex
cessive temjjerature rise, i si;ould
not be used in areas where the
ambient temperature exceeds SO'C
(122°F). To determine i .imbient air temperature, opemte the
system in the rack until the tem
perature stabilizes. Mea'"ro the
ambient air with a bulb-type ther
mometer held at the botloin of the
uppermost amplifier. Dc tmt let
the thermometer touch the netal
chassis because the chassis will be
hotter than the ambient a:.-. If the
air temperature exceerls 50°C
(122°F), the equipment siiould 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.
ALTEC LANSING* CORPORATION • a Mark IV Company
Operating and Service Instructions for the Altec Lansing 9441A Power Amplifier
For example, suppose an installer
uses 160 feet of 10 GA 2-wire
cable with an 8 H speaker system.
WHITE (A.a HECEPTAia^
The total po%ver loss in .U. cable
is;
A. 120 V ac Primary Wiring
X I ^
WHITE (A.C RECEPTACLE)
BIACK BUWHT BLUE
BLACK BLIWirr BLUE
_______________
nV/HT BROWN
8.240 V ac Primary Wiring
BRIWHT BROWN
Figure 2 Primaiy Wiring Configuration for 120 V ac and 220/240 V ac
SIGNAL CONNEC
TIONS
3.1
Input Connection.s
Balanced input connec
tions may be made to either the
Va phono (TRS) or the female
XLR connectors. For single-ended
inputs, strap the low (—) input to
ment. Refer to Figure 3 for po.ssi-
ble 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
tj'pical output connections.
ground (pin 3 on XLR or Ring on
Va" phone). Otherwise, the elect
ronically-balanced input stage will
see 6 dB loss input signal level
than with a balanced input. Refer
to Figure 3 for typical input con
nections.
3.4 Output Cable Selection
Speaker wire size plays an
important part in quality sound
systems. Small wire gauges can
waste power and reduce the
damjiing factor at the speaker
terminals. This can add coloration
3.2 Line Output Connec
tions
TliD XLR and Vi" phone
connectors are wired in parallel.
Pin 2 of the XLR is the Tip of the
and muddincss to the sound. To
help offset this problem. Table I
has been assembled to enable you
to calculate the power losses in
the speaker cable.
Va" phono comiector, and pin 3 is
the Ring. Since the input imped
ance of the electronically-balanced
input stage is high (15 kohms),
there is minimal loading on the
signal source, Wien the input
connections are made to one con
nector, the other may be used as
an auxiliary line output to feed
other high input impedance equip
3.4.1 Calculating Power
Losses with 8 ohm
Loads
To calculate the total
power loss in the spealcer cable,
multiply the power loss per foot
(or meter) of the 2-wire cable sel
ected from Table 1 by the length
of the cable in feet (or meters).
Total Power Loss in cable
= 0.0191 watts/foot X lOr feet
= 3.0 watts
Does this mean that whena er the
amplifier produces 75 walls of
output power, 72.0 watts (75 watts
minus 3.0 watts) will be delivered
to the 8 ohm load? N'^d The
actual load impedance is ohms
plus the resistance of Iht cable
(0.00204 ohms/foot times L'"' feet)
for a total load imped.nice of
8.3264 ohms. At the 8 lated
output power, the output, /oltage
is 24.4 V rms. Therefore, I t ■ amp
lifier produces 71.5 wati - with
this load instead of 75 wa.‘ . This
was calculated by squaring the
voltage and dividing by I load
impedance (24.4* divid. i by
8.3264 ohms). As a result, ue act
ual power delivered to thf !-ad is
68.5 watts (71.5 watts minus 3.0
watts).
Had 18 GA wire been used hi the
above example, the lass in the
cable would have been Ifl.r ivatts.
Tliis example lllustrale.s I im
portance of using the pro; . wire
size.
3.4.2 Calculating <wer
Losses with 4 ohm
Loads
To calculate the- i sses
when using a 4 ohm speak .-; os
tein, multiply the loss at hms
by 3. In the above exampk-. the 10
GA wire would consume 9,'' watts
of power while the 18 GA '.■.•ire
would waste 58.5 watts more
than half of the amplifier’’^ ohm
power rating.
3.5 Damping Factor
The higher the da aping
factor rating of an amplill'-!' the
greater the ability of the am; lifier
A1.TEC lANSING' CORPORATION * a Mark T\' Company
Operating and Service Instructions for the Altec Lansing 9441A Power Amplifier
inward but its niomontum cmises
it to overshoot its resting point.
SOURCE AMPLIFIER'S INPUTS
BALANCED
SOURCE
BALANCH3
SOURCE
H/600 OHM
TERMINATION
UNBALANCED
SOURCE
------------
UNBALANCED
SOURCE
/, 1
LO (-)
HOT
HOT
J COM
'G j
r
NC
Figure 3 Topical Input Connections
SINGLE-ENDEO AUX OUTPUT
XLn BAFIflIEH STRIP
2 (+)
3 (-)
6Ю ¡-
7lr ^
ЯЛ
ВАИЙ1ЕП STHIP
2
Э
—t i
(t)
H
E.ND ,
%
Ж.
-----
AUX OUTPUTS
(USER OPTIONS)
BAL
OUTPUT
HOT
KEEP
COM
CABLE
RUNS
UNDER
6 ft
HOT
OR 2 m
COM
NC
This overshoot will dampen itself
out eventually but the unwanted
movements can add consitlerable
distortion products to tlu touiul.
In the process of moving hv.vard
through the magnetic fieUh the
voice coil assembly generatos a
current of opposite polarity tn the
original signal. This current in
duces a voltage or "back EMF”
which travels through the speaker
wire to the amplifier's '.utput.
The lower the amplifier’i. output
impedance, the faster tl.o overslioot of the voice coil will dampen
out. The output impedii'io; of an
amplifier can be calculated by
dividing the rated output linped-
ancG, typically 8 ohms, uy the
damping factor. The 944 i A has a
damping factor rating ; 100
which corresponds to an 4Utput
impedance of 0.08 ohni.s.
AMPLIFIER'S OUTPUTS
SPEAKER OUTPUTS
CH 1 L‘
eniOGE OUTPUT Q I I
CH г
BRIDGE MODE
Figure 4 'Topical Output Connections
to control unwanted speiiker cone
movements. When a signal drives
a woofer, current flowing through
the voice coil creates a magnetic
field. This field interacts with the
LOUDSPEAKER LOADS
HIGH POWER
FULL RANGE/
=0]
SUBWOOFER
permanent magnetic field in the
gap and forces tlie combination
cone and voice coil assembly to
move outward. When the signal is
removed, the assembly moves
3.5.1 Calculating the
Maximum Length of
Cable for a Spenified
Damping Factor Spec
ification at the Load
Tlie damping factor rating
is typically never realiz-т-: at the
load because of the rosisLunce of
the cable (and other facLnia such
as the contact resistance of an
output relay or the resistance of
an output fuse). Tlie damping fac
tor at the load should be 30 for
general paging systems ami 50 for
high fidelity music systcm.s. Econ
omics usually dictate, however,
that these numbers are cut-in
half. The resulting dampiiig factor
at the load should be based on ex
perience and customer satis
faction. Once a minimum; c ciiiping
factor is determined for => partic
ular type of installation, the fol
lowing equation can calculate the
maximum length of 2-wire cable
which can be used to achieve the
minimum damping factor .s^x cified
at the load:
ALTEC LANSING* CORPORATION • a Mark TV Company
Operating and Service Instructions for the Altec Lansing 9441A Power Amplifier
Max. Length of 2-wire cable in
feet
ZL — Zo
= DF
DCR/ft
where
ZL is thé load impedance
to comiect to the amp
lifier;
Zo is the amplifier’s out
put impedance (0.08 ohms
for the 944lA);
DF is the minimum permi.ssible damping factor at
tlie load; and
DCR/ft i.s the DC resis
tance of the 2-wire cable
per foot from Table I.
The same equation can be used to
calculate the maximum cable
length in meters by substituting
the DCR per meter value from
Table I.
Let’s use the equation. Suppose
ZL equals 8 ohms, Zo = 0.08
ohms, and the minimum damping
factor at tlic load is 25. In addi
tion, IS GA cable is preferred.
Then, the maxiinxim length of 18
GA cable which can be used to
achieve a damping factor of 25 fit
the load is;
8
25
(0.08)
IS.4 feet
0.01302 n/ft
Table I 9441A Power Losses in 2-wire Speaker Cable
Power
AWC, nc:n/fi I.ciss/n Socllonal UCR/iTicler I^ishKlcr
(0Л) (îVil) (willt.s/(1)
G 0.Ü0Û8I
8 0.00121 0.0i:)4 8.30 0.0042I 0.0394
10
12
И
IG
18 0.01302 0.1218 0.82
20 0.02070 0.1935
22
0.0020'!
0.00324
O.OO.'il.'i 0.0482
0.0081!)
0.03202 0.:t073
0.0075
0.0191
0.0303 3.31
0.0767
Figure 5 High-voltage Distribution System
Sometimes it may be necessarj' to
locate the speaker 100 feet or
more away from the amplifier. In
this situation, a much larger
gauge cable is required. However,
this may not be jiractical or eco
nomical. The size of the 2-wire
cable can be greatly reduced by
stepping up the output voltage of
tlie amplifier to 70, 100, 140, or
210 volt, using an output trans
former, then stepping down the
voltage at the load. Such a system
is shown in Figure 5.
Cable Crossarea (iiim*) (U/m)
13.30 0.00204
5.26 0.00669
2.08 0.01691
I.3I 0.02085 0.2508
0.52
0.33 0.10658
0.01063 0.0052
0.042S9 0.39Î16
0.06764 0.6288
Power
(woUs,/m)
0.0247
0.0626
0.1581
0.9860
I'he maximum
cable in this situation can be
approximated from the following
equation:
Max. Length of 2-wire o;
feet
(Pout)(DCR./ft)
where
V is the stejipod-up
voltage of the system;
Pout is the rated output
power of the amidifier;
Zo is the output imfiedance of the amplifier (0.08
ohms for the 9441A r,
ZL is the load impeo.mce;
DCR/ft is tb. DC
resistance of th: 2-wire
cable per foot from Table
I; and
DF is the minimum
permissible damping fac
tor at the load.
length of v-v/ire
ie in
Zo
J_
ZJ.
DF
ALTEC LANSING* CORPORATION © a Mark IV Company
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