O W N E R ' S
M A N U A L
H C A - 1 2 0 5 A H i g h C u r r e n t P o w e r A m p l i f i e r
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HCA-1205A Five Channel High Current Power Amplifier
H C A - 8 5 5 A H i g h C u r r e n t P o w e r A m p l i f i e r
Current Overload
Power
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Standby
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HCA-855A Five Channel High Current Power Amplifier
IMPORTANT SAFETY INSTRUCTIONS
The lightning flash with the arrowhead symbol within an equilateral triangle is intended to alert the user to
the presence of “dangerous voltage” inside the product that may constitute a risk of electric shock.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of important
operating and maintenance instructions in the literature accompanying the product.
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER. NO USER-SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL
1. Read Instructions — Read all the safety and operating instructions before operating this product.
2. Retain Instructions — Retain safety and operating instructions for future reference.
3. Heed Warnings — Adhere to all warnings on the product and in the operating instructions.
4. Follow Instructions — Follow all operating and use instructions.
5. Cleaning — Unplug this product from the wall outlet before cleaning. Use a damp cloth for cleaning. Clean the
outside of the product only.
6. Attachments — Do not use attachments that are not recommended by the product manufacturer; they may be
hazardous.
7. Water and Moisture — Do not use this product near water.
8. Accessories — Do not place this product on an unstable cart or stand. The product may fall causing bodily injury
and damage to the product. A product and cart combination should be moved with care. Quick stops, excessive
force, and uneven surfaces may cause the product and cart to overturn.
9. Ventilation — Slots and openings in the cabinet are provided for ventilation to ensure reliable operation of the
product and to protect it from overheating. These openings must not be blocked or covered. This product should not
be placed in a built-in installation such as a bookcase or rack unless proper ventilation is provided.
10. Power Sources — Operate this product only from the type of power source indicated on the label. If you
are not sure of the type of power supply to your home, consult your dealer or local power company. This product is
equipped with a three-prong grounding plug. This plug will only fit into a grounding power outlet. If you
are unable to insert the plug into the outlet, contact your electrician to replace your obsolete outlet. Do not defeat the
safety purpose of the grounding plug.
11. Power Cord Protection — Power supply cords should be routed so that they are not likely to be walked on or
pinched by items placed upon or against them.
12. Lightning— Unplug the unit from the wall outlet for added protection during a lightning storm and when it is left
unattended and unused for long periods of time. This will prevent damage to the product due to lightning and power
line surges.
13. Overloading — Do not overload wall outlets or extension cords. This can result in a fire or electric shock.
14. Inserting Objects into Unit - Never push objects of any kind into this product through any openings; they may
touch dangerous voltage points or short out parts that could result in fire or electric shock.
15. Servicing — Do not attempt to repair or service this product yourself. Opening or removing covers may expose you
to dangerous voltage and other hazards. Refer all servicing to qualified service personnel.
16. Damage Requiring Service — Unplug this product from the wall outlet and refer servicing to qualified service
personnel under the following conditions: a) If the power-supply cord or plug is damaged. b) If liquid has been
spilled into the product. c) If the product has been exposed to rain or water. d) If the product does not operate
normally by following the operating instructions. e) If the product has been dropped or damaged in
any way. f) If the product exhibits a distinct change in performance.
17. Replacement Parts — When replacement parts are required, be sure the service technician has used replacement
parts specified by the manufacturer. Unauthorized substitutions may result in fire, electric shock, and other hazards.
19. Safety Check — Upon completion of any service or repairs to this product, ask the service technician to perform
safety checks to determine that the product is in proper operating condition.
20. Wall or Ceiling Mounting — Mount the product to a wall or ceiling only as recommended.
21. Heat — The product should be situated away from heat sources such as radiators, heat registers, stoves, and other
products (including amplifiers) that produce heat.
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Introduction
Congratulations on your purchase of this precision audio component and thank you for your selection of
Parasound. The Parasound HCA-1205A and HCA-855A five channel amplifiers are virtually identical
in operation and sonic performance. However, the HCA-855A has slightly less power and is therefore
not THX certified like the HCA-1205A. Please take a few moments to read these instructions so that you
may fully understand the capabilities of your new Parasound power amplifier.
Unpacking Your Amplifier
Carefully unpack your amplifier and remove all the enclosed accessories. Be sure to inspect the unit for
any possible shipping damage. If you see any, contact your Parasound Dealer immediately. Save all the
packing material in case you need to ship the amplifier for repair. Before you proceed, find the serial
number located on the rear panel of your amplifier and record it here for reference:
Serial #____________________
DateofPurchase____________________
Installing and Rack Mounting Your Amplifier
Place your amplifier away from heat sources such as air ducts and radiators. Always mount the amplifier
horizontallyandmakesurethatyourcabinetorshelfcansupportitsweight. Itisbesttoprovideaseparate
shelf for your amplifier rather that stacking it directly above or below other components.
With the use of the optional Parasound RMK-3, both the HCA-1205A and HCA-855A occupy three rack
spaces (5 1/4") in a standard 19 inch equipment rack. Be sure to use the heavy duty mounting bolts with
nylon shoulder washers on both sides of the faceplate to avoid scratching the amplifier’s front panel and
tohelppreventgroundloops. ThismountinghardwareisincludedwiththeRMK-3. Whenrackmounting
equipment, have someone help support the unit while you bolt the component to the rack rails.
Ventilation Requirements for Your Amplifier
To insure safe and reliable operation, it is very important that the amplifier has plenty of ventilation to
prevent overheating and automatic shut down from its thermal protection circuitry. Please observe the
following ventilation guidelines when installing your amplifier in a cabinet or other enclosed area:
1) If you are not using a fan, allow at least six inches on each side and above the amplifier, and do not
close off the front with a cabinet door or panel.
2) If you are enclosing the amplifier within an equipment cabinet, use a fan to draw in cool air and
exhaust warm air. Two vent holes are required: one for intake and one for exhaust.
3) Do not place the amplifier on carpeting that will obstruct the air flow into the bottom of the amplifier
chassis and heatsinks.
4) Avoid stacking components. If you do stack components, you must use a fan to circulate the warm air
that will quickly become trapped between them when they are powered on.
Making Connections toYour Amplifier
Leave the AC cord disconnected while making any input or speaker connections. When making
connections to the amplifier, make sure there is no strain or tension on the input leads, speaker wires, or
AC cord that could cause them to pull loose.
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Home Theater Configurations and Input Connections
Refer to Figure #1 or Figure #2
Your Parasound multi-channel amplifier is designed to deliver the same power and sonic characteristics
to the Left, Center, Right, and both Surround speakers of your home theater system. For additional low
frequency response, you should also install a powered subwoofer. Even though all the channels of your
amplifier operate identically, we recommend the following configuration to make it easier to identify
each channel in case you ever need to troubleshoot your system.
• Connect the right front output of your processor to INPUT 1 of your HCA-1205A or HCA-855A.
• Connect the left front output of your processor to INPUT 2 of your HCA-1205A or HCA-855A.
• Connect the center output of your processor to INPUT 3 of your HCA-1205A or HCA-855A.
• Connect the right surround output of yourprocessortoINPUT 4ofyourHCA-1205A or HCA-855A.
• Connect the left surround output of your processor to INPUT 5 of your HCA-1205A or HCA-855A.
• Connect the subwoofer output of your processor to the input of your powered sub or sub amplifier.
Speaker Connections
You can connect speaker cables to the amplifier's rear mounted 5-way binding posts using speaker wire
terminated with 1/4" spade lugs or banana plugs. You can also insert bare wire up to AWG 12 into the
holes on the sides of the binding posts. If you use bare wire, remove only about 1/2" of insulation and
twist the wire's strands tightly to prevent strays that could cause a short circuit. (You may want to "tin"
the stripped wire with solder to prevent it from fraying and oxidizing.)
Polarity
When you connect speakers to your amplifier, you will notice that one side of the two conductor speaker
wire will have some sort of mark: either printing, a raised ridge on the insulation, or a different color of
conductor. The marked insulation or copper colored wire usually indicates the positive conductor. This
demarkation lets you know which wire is connected to the positive and which to the negative speaker
terminals so you can do exactly the same on the power amplifier's colored (+) and black
(-) binding posts.
Minimum Impedance Precautions
Connect loudspeakers with a 4 Ω or 8 Ω nominal impedance for normal operation. Both amplifiers are
capable of driving speakers with occasional impedance dips below 2 Ω. However, sustained high power
operation into loads of less than 4 Ω may cause overheating and is not recommended.
AC Power Connections and AC Grounding
Before you connect the AC cord, make sure your amplifier's power switch is in the off position and the
external DC trigger is off. If possible, plug your amplifier directly to an AC wall outlet. Do not connect
theamplifiertotheaccessoryACoutletonyourpreamplifierorprocessorbecausetheamplifier'scurrent
drawwillexceedtheratingofmostpreamplifier’spowerswitchesandpowercords.Ifyouuseanexternal
AC line conditioner or surge suppressor, make sure it can withstand the power requirements of the
amplifier listed in the specification section of this manual.
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DC Trigger Connection
The DC Trigger allows you to turn on your amplifier with external DC voltage sources from + 9 Vdc to
+12 Vdc. Use a two-conductor wire such as an 18 AWG speaker wire to connect the DC trigger from an
external source to your amplifier. You should first determine the + DC voltage and ground conductor
from the external source. For example, the AVC-2500 has DC trigger that uses an 1/8" mini jack where
the tip is positive and the ring is negative (ground). In this case, you would terminate one end with an
1/8" mini plug and strip off a 1/4" of insulation and use bare wire on the other end. Connect the positive
lead to the screw labeled +12 V on the amplifier’s DC trigger connector and the negative (ground) lead
to the screw labeled GND. With the main power switch in the off (down) position, the amplifier can now
be turned on with the external DC source.
Operating Your HCA-1205A or HCA-855A
Power Switch
Manual Turn On
Press the upper side to turn the unit on manually; press the lower side to turn the unit off.
Automatic Turn On
When the power switch is in the off position, the power amplifier can be turned on with an external DC
voltage applied at the DC trigger connector on the rear panel.
AC Line LED
The AC line LED on the front panel of your amplifier will illuminate whenever AC is present at the AC
connector. This LED indicates that the AC cord is connected and that power is currently applied to the
amplifier.
Standby/Normal Operation LEDs
TheredStandbyLEDwilllightwhentheamplifieristurnedoneitherwiththepowerswitchoranexternal
DC trigger. It will stay lit about four to five seconds while the amplifier circuits stabilize. After that, the
red LED will turn off and the green normal LED will signal that the protection relays have switched off
and that amplifier is ready to operate. The Standby LED will also light whenever there is a short circuit
or other fault that triggers the protection circuitry. This may indicate one of the following conditions: DC
present at the amplifier's input, a speaker impedance overload, a short circuited speaker line, or possible
internal fault. If this LED remains lit, remove power to the amplifier and check all connections. During
this time, the protection circuits should automatically reset. If the red LED stays lit after you reapply
power, contact your Parasound Dealer, Installer or Parasound Technical Service for further advice.
Current Overload LEDs
The Current Overload LEDs for each channel only illuminates if the unit is driven past its maximum
current capacity. These LEDs are not clipping indicators, but are designed to signal when you are
exceedingthelimitsofyouramplifier.IftheseLEDslight,it’susuallyasignthatyourspeakerimpedance
is too low, resulting in too much current draw from the amplifier's power supply. In most imaginable
listening situations with recommended loads, these LEDs should not illuminate.
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Level Controls
Each channel has its own rear mounted "set and forget" input level control. Your amplifier sounds best
with these level controls set to maximum, where they are effectively out of the audio signal path.
However, if your preamplifier has very high gain, and its volume control cannot track properly for left-
right channel balance near its minimum position, it may be necessary to reduce the input level control
settings on the amplifier. When using the HCA-1205A in a THX installation, each level controlmust be
set at maximum to correspond to 0 dB THX reference level.
Maintaining Your Parasound Amplifier
Your Parasound power amplifier requires no periodic maintenance and has no user serviceable parts
inside. Toavoidtheriskofelectricshock, donotremovethetopcover. Theamplifier'sexteriorcaneasily
be cleaned with a soft cloth moistened only with a few drops of water or glass cleaner.
Main Power Fuse
There is an external fuse located within the AC receptacle that may blow as a result of an internal fault
condition. This fuse protects the unit from possible damage to internal parts. Never replace this fuse with
afuseofhighervaluethaninstalledfromthefactory.Substitutionofalargerfusemaycreateseriousstress
and damage to internal parts and will void your warranty.
In Case of Trouble
If you suspect a problem with your amplifier, first turn the amp off and check all your connections. The
trouble may be caused by another component or even a defective hookup cable. If you are hearing hum
out of any of your speakers, turn off the amplifier and disconnect the inputs to it. If the hum goes away,
it was probably be caused by your processor or one of the source components connected to it.
Frequently, hum in home theater systems is caused by a grounding problem with the cable TV system.
Contactyourcableproviderifnecessarytomakesurethecablefeedintoyourhouseisproperlygrounded.
TherearecableisolationdevicesavailablesuchastheVideoLink#634ortheMondialMagicspecifically
designed to cure this problem. In rack mounted systems, ground loops and hum can sometimes develop
via the metal rack rails of the equipment rack. This problem can be solved with nylon shoulder washers
mentioned in the rack mounting section of this manual.
If All Else Fails...
Call your Parasound dealer or Parasound Technical Service. We can suggest other diagnostic tests you
can easily perform. Ifwe determine that youramplifiershouldbe returnedtoParasoundoranAuthorized
Parasound Warranty Center for inspection and possible servicing, call Parasound for the location of a
warranty center near you. If you choose to send it to Parasound, contact us to obtain a Return
Authorization (RA) number. You will be asked to repack the unit in its original packaging including the
additional outer box for protection during transit. The Return Authorization number must be clearly
marked on the outer carton only. You should ship the unit by UPS with adequate insurance and a copy
of your purchase receipt to validate your ownership. Units that arrive without your specific Return
Authorization number, without a suitable shipping carton or with evidence of improper internal packing
mustberefused.Wedonotacceptcollectshipments.Afterrepairunderwarranty,theunitwillbereturned
toyouviaprepaidUPS.Inthecaseofanon-warrantyrepair,contactusandwewilladviseyouoftherepair
charges before you ship the unit to us. The same packing and RA number requirements apply.
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Parasound HCA-1205A Specifications
Continuous Power Output
140 watts RMS x 5, 20 Hz-20 kHz, 8 Ω,
200 watts RMS x 5, 20 Hz-20 kHz, 4 Ω,
Current Capacity
45 amps peak per channel
Slew Rate
> 130 V/microsecond
Power Bandwidth
5 Hz-100 kHz, +0/-3 dB at 1 watt
Total Harmonic Distortion
< 0.03 % at full power; < 0.01 % typical levels
IM Distortion
< 0.03 %
TIM
Unmeasureable
Dynamic Headroom
> 1.5 dB
Interchannel Crosstalk
> 80 dB at 1 kHz
> 60 dB at 20 kHz
Input Impedance
33 kΩ
Input Sensitivity
1 V for 28.28 V; THX Reference Level; 1.2 V for full output
S/N Ratio
> 117 dB full power; > 96 dB THX reference level
Damping Factor
> 800 at 20 Hz
Dimensions
17" wide x 5 1/4" high x 19" deep (6" high with feet)
Power Requirements
110 Vac-120 Vac 1000 Watts
Net Weight
46 lb
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Parasound HCA-855A Specifications
Continuous Power Output
85 watts RMS x 5, 20 Hz-20 kHz, 8 Ω
125 watts RMS x 5, 20 Hz-20 kHz, 4 Ω
Current Capacity
30 amps peak per channel
Slew Rate
> 130 V/microsecond
Power Bandwidth
5 Hz-100 kHz, +0/-3 dB at 1 watt
Total Harmonic Distortion
< 0.03 % at full power; < 0.01 % typical levels
IM Distortion
< 0.03 %
TIM
Unmeasureable
Dynamic Headroom
> 1.5 dB
Interchannel Crosstalk
> 80 dB at 1 kHz
> 60 dB at 20 kHz
Input Impedance
33 kΩ
Input Sensitivity
1 V for 28.28 V 1.2 V for full output
S/N Ratio
> 115 dB, full power, IHF A-weighted
Damping Factor
> 800 at 20 Hz
Dimensions
17" wide x 5 1/4" high x 16" deep (6" high with feet)
Power Requirements
110 Vac-120 Vac 750 Watts
Net Weight
41 lb
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Parasound Products, Inc. 950 Battery Street, San Francisco, CA 94111
415-397-7100 / FAX 415-397-0144
© 1999 Parasound Products, Inc.
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