background image

CONNECTING YOUR SPEAKERS TO THE A 51

Speaker Terminals

The A 51 speaker terminals accept speaker wires with banana plugs or bare ends. Refer to Bare Wire
Speaker Termination in the 

Technically Speaking

section for information about bare wire termination.

What You’ll Need:

Five lengths of AWG 16 or thicker speaker wire 
with banana plugs or bare ends

Five loudspeakers 

Before Connecting

Remove power to all the components in your audio system.

To Connect

Because the speaker terminals are very close to each other, the bare wire ends insert diagonally
into the terminal shafts. The - (negative) wires enter the black - terminals at 8 o’clock. The  +
(wires) enter the red + terminals at 4 o’clock. The resulting 45 degree angles of the speaker
wires routes them outside the terminals of the channels below. It’s easier to connect speaker
wires if you start with the bottom terminals for Channel 5 and proceed upward. 

1

Insert one wire with the ridge or other marking into the red 

Ch 5

+ (positive) speaker 

terminal on the A 51. Insert the wire without the ridge or other marking into the adjacent
black 

Ch 5

- (negative) speaker terminal on the A 51.

2

Insert the other end of the wire with the ridge or other marking to the red + (positive) 
terminal on the speaker. Insert the other end of the wire without the ridge or other marking
to the adjacent black – (minus) terminal on the speaker. 

3

– 

0

Repeat steps 1 and 2 for 

Ch 4

, then 

Ch 3

, then 

Ch 2

, and finally 

Ch 1

5

Parasound Products, Inc.

San Francisco, CA USA

Manufactured under

license from Lucasfilm

Ltd. Lucasfilm and THX

are registered Trademarks

of Lucasfilm Ltd.

CAUTION
To Prevent Electric Shock, 
Do Not Remove Cover. No 
User-Serviceable Parts Inside, 
Refer Servicing  To Qualified 
Service Personnel.

L U C A S F

I

L M

L M

A51 Amplifier

WARNING

To Prevent Fire Or Shock 
Hazard, Do Not Expose This 
Unit To Rain Or Moisture.

AC 115V      60Hz
AC 230V      50Hz

Power Consumption: 1800W

Input

12 V

Man

Audio

50  mV  250

Ground

Normal

Lift

Auto Turn  On

Sensitivity

Fuse

T15A/250V1-115V Area

T8A/250V-230V Area

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Balanced

Unbalanced

Input Select

9

7

5

3

1

SPEAKERS

10

8

6

4

2

YOU SHOULD KNOW

Correct Speaker Polarity is Important

Polarity refers to + and – connections. Speaker wires are coded with printing or a ridge on the
insulation on one of the leads so you know which lead was connected to the + and – terminals
at the other end. This coding will help you keep the + and - polarity consistent for all channels. 

Speaker Wire Length and Gauge (thickness)

When selecting speaker wire, follow these guidelines:

• Keep the length of your speaker wire as short as possible.
• Use the thickest wire practical. For lengths greater than 50 feet, use speaker wire

with an AWG (gauge) of 14 or lower. The smaller the AWG, the thicker the wire.

• Do not use speaker wire that is thinner than 16 AWG.
• Keep wire lengths for both channels as close to equal as possible.

Stripped
AWG wire

Dual

Banana Plug

Common Speaker Connectors

Single

Banana Plug

Summary of Contents for Halo A 51

Page 1: ...A 51 Amplifier Owner s Guide ...

Page 2: ...oroughly for possible shipping damage If you see any contact your Parasound dealer right away Be sure to save and store both the inner and outer cartons and the packing inserts for possible future transport To save room for storage you can cut the seams on the bottom of the cartons and flatten them Keeping Records for Future Reference Record the serial number located on the bottom of your A 51 in ...

Page 3: ...PUTS ON YOUR A 51 4 CONNECTING YOUR SPEAKERS TO THE A 51 5 MANUAL AND AUTOMATIC TURN ON OFF OPTIONS 6 CONNECTING AN EXTERNAL DC SOURCE FOR AUTOMATIC ON OFF 7 UNDERSTANDING THE INDICATORS ON THE A 51 8 CONNECTING THE AC POWER CORD 9 MAINTAINING YOUR A 51 10 TROUBLESHOOTING GUIDE 11 SERVICING YOUR A 51 12 TECHNICALLY SPEAKING 13 PARASOUND A 51 DESIGN OVERVIEW 15 PARASOUND A 51 SPECIFICATIONS 17 ...

Page 4: ...ust first attach its rack mount brackets provided With its four feet removed the A 51 chassis and front panel height occupies four rack spaces 7 or 176 mm When mounting equipment below the A 51 you will also need to allow about 1 8 below the unit for the bottom chassis screws A single standard rack space allows 13 4 vertical height in a 19 wide equipment rack This measurement standard was devel op...

Page 5: ...r surround controller that you wish to correspond to Ch 1 on your A 51 3 0 Repeat steps 1 and 2 above to connect Ch 2 Ch 3 Ch 4 and Ch 5 3 Parasound Products Inc San Francisco CA USA Manufactured under license from Lucasfilm Ltd Lucasfilm and THX are registered Trademarks of Lucasfilm Ltd CAUTION To Prevent Electric Shock Do Not Remove Cover No User Serviceable Parts Inside Refer Servicing To Qual...

Page 6: ...that you wish to correspond to Ch 1 on your A 51 3 0 Repeat steps 1 and 2 for Ch 2 Ch 3 Ch 4 and Ch 5 4 SURROUNDŁ CONTROLLER OUTPUTS 2 4 6 8 10 Parasound Products Inc San Francisco CA USA Manufactured under license from Lucasfilm Ltd Lucasfilm and THX are registered Trademarks of Lucasfilm Ltd CAUTION To Prevent Electric Shock Do Not Remove Cover No User Serviceable Parts Inside Refer Servicing To...

Page 7: ...at steps 1 and 2 for Ch 4 then Ch 3 then Ch 2 and finally Ch 1 5 Parasound Products Inc San Francisco CA USA Manufactured under license from Lucasfilm Ltd Lucasfilm and THX are registered Trademarks of Lucasfilm Ltd CAUTION To Prevent Electric Shock Do Not Remove Cover No User Serviceable Parts Inside Refer Servicing To Qualified Service Personnel L U C A S F I L M L M A51 Amplifier WARNING To Pre...

Page 8: ...ain on for about five minutes This delay prevents unwanted turn off during silent passages in music or during the pauses between tracks Parasound Products Inc San Francisco CA USA Manufactured under license from Lucasfilm Ltd Lucasfilm and THX are registered Trademarks of Lucasfilm Ltd CAUTION To Prevent Electric Shock Do Not Remove Cover No User Serviceable Parts Inside Refer Servicing To Qualifi...

Page 9: ...San Francisco CA USA Manufactured under license from Lucasfilm Ltd Lucasfilm and THX are registered Trademarks of Lucasfilm Ltd CAUTION To Prevent Electric Shock Do Not Remove Cover No User Serviceable Parts Inside Refer Servicing To Qualified Service Personnel L U C A S F I L M L M A51 Amplifier WARNING To Prevent Fire Or Shock Hazard Do Not Expose This Unit To Rain Or Moisture AC 115V 60Hz AC 23...

Page 10: ... or wire After you correct the fault the A 51 will resume operation If the A 51 remains in protection after it has cooled down and you ve confirmed there are no external faults it could indicate an internal problem Please contact Parasound s Technical Service Department c g Channel Status Indicators These are the five small round indicators in the center of the recess in the front panel The indica...

Page 11: ...ferred to a qualified technician What You ll Need An IEC 65 AC Cord provided An AC outlet or high quality AC power strip within reach of the AC cord Before Connecting Remove power to all the components in your audio system To Connect 1 Plug the female end of the AC cord to the AC receptacle on the rear of the A 51 2 Plug the male end of the AC cord to an AC outlet or power strip 9 2 1 Parasound Pr...

Page 12: ...eable parts inside To avoid the risk of electric shock do not remove its top cover The amplifier s exterior can easily be cleaned with a soft cloth pre moistened only with a few drops of water or glass cleaner Main Power Fuse If this fuse blows please contact Parasound Technical Service for further advice Notes 10 ...

Page 13: ...k polarity of DC source with a voltmeter Try connecting a 9V battery to the 12V DC input Make sure Auto Turn On selector switch is in its 12V position Make sure Auto Turn On selector switch is in its Audio position Turn the Audio trigger Sensitivity knob counterclockwise Turn Sensitivity knob clockwise toward 250 mV Check input connections or try a different set of cables Check speaker load impeda...

Page 14: ...pt any of the following Units with collect shipping charges Units without a valid RA number Units without a suitable shipping carton Units for which we see or hear evidence of improper packing For a non warranty repair contact us for an estimate of the repair charges before you ship the unit to us The same packing and Return Authorization number procedures apply Important Notice Shipping the A 51 ...

Page 15: ...een the positive and negative signals For exam ple when a 1 Volt signal arrives at a balanced input stage the differential input sees a positive 1 Volt minus a negative 1 Volt or 2 Volts total External hum and noise that somehow gets into a balanced line is common to both its positive and negative conductors with respect to ground Therefore it is canceled or rejected by the differential input circ...

Page 16: ... rack the components and their rack mount bolts Extra washers are available from rack manufacturer Middle Atlantic Products www middleatlantic com 3 Use the Ground switch on the A 51 to eliminate most ground loops This separates the A 51 s signal input ground from its chassis ground to isolate unwanted voltage in the ground shield of the unbalanced RCA input cable Be sure your system installation ...

Page 17: ...ere instru ments dialogue and effect are positioned Each channel s 80 Vdc B and B supply rails use high speed rectifier diodes and four enormous 8 200 uF electrolytic filter capacitors chosen for their low Equivalent Series Resistance ESR and dielectric absorp tion In addition these filter capacitors are bypassed with smaller polypropylene capacitors to reduce AC ripple in the DC supply and to fur...

Page 18: ...s A while its output stage operates with higher pure Class A power than many amplifiers selling for twice or three times its price The result is less fatiguing more natural sound Total Protection DC Servos Direct Current DC burns out speakers Every power amplifier must have some way to insure that DC from its power supply never reaches its or speaker ter minals Most amplifiers simply use trim cont...

Page 19: ...Hz 63 dB at 20 kHz Input Impedance Unbalanced 47k Ω Balanced 94k Ω Input Sensitivity for 28 28 V Output into 8 Ω Unbalanced 1 V Balanced 1 V per leg S N Ratio 112 dB input shorted IHF A weighted 102 dB input shorted unweigh Damping Factor 1100 at 20 Hz DC Trigger Requirements 9 Vdc to 12 Vdc 2 mA Audio Trigger Requirements 50 mV AC 250 mV AC Dimensions Width 171 2 445 mm Panel height 7 178 mm Heig...

Page 20: ...Parasound Products Inc 950 Battery Street San Francisco CA 94111 415 397 7100 Fax 415 397 0144 www parasound com ...

Reviews: