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: (405) 324-5311 • FAX: (405) 324-8981

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

Table of Contents

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

1.1120 V ac, 50/60 Hz Power Connections......................................................................................................

1.2220/240 V ac, 50/60 Hz Power Connections...............................................................................................

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

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

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

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

3.0

Damping Factor...........................................................................................................................................

 

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

• i

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

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

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

^

9.7Ordering Replacement Parts

9.8Factory Service ..........................................................................................................................................

9.9Technical 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.

1.1120 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.

1.2220/240 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, Littelfuse Type ЗАВ 5A/250V slo-blo 326-series ceramic body or equiv.

2 INSTALLATION

2.1Rack 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.

2.2Ventilation

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

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

3.1Input 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.

3.2Line 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.

3.3Output 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.

3.4Output 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.

3.4.1Calculating 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

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