Halo A 21 Manuel utilisateur

A 21 Amplifier

Owner’s Guide

THANK YOU!

Congratulations and Thank You for Choosing Parasound

Your new Parasound Halo Series A 21 power amplifier presents the latest advancements

in amplifier technology. The A 21 is built to the strict quality and performance standards

set by Parasound. We’re proud to offer you this exceptional audio component that will

bring you many years of enjoyment and dependability.

Here at Parasound, we design our products to perform at a higher level of flexibility

and sonic performance than you may have expected. We encourage you to read

this entire manual to learn all the features and capabilities of your new Halo Series

A 21 Amplifier.

If you’re eager to get up and running right away, simply follow the basic step-by-step

instructions to connect and operate the A 21. If you want to learn about some of the

technical and design aspects of your A 21, refer to the Technically Speaking and

Parasound A 21 Design Overview sections in the back of the manual. If you run into

difficulties, the Troubleshooting Guide should help you quickly remedy the problem.

We appreciate you taking the time to read these instructions and thank you for

selecting Parasound for your listening pleasure.

The Parasound Staff

Unpacking Your A 21

Unpack your A 21 from the shipping carton, remove the enclosed rack mounts, AC

power cord, and the control wire with 2.5 mm sub-mini plugs on each end. (This is

the trigger connection wire). While you are unpacking your new amplifier, inspect

it thoroughly 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 21 in the space below. Also

note your Parasound Dealer’s name and phone number. We recommend that you keep

your purchase receipt with this manual and store them both in a safe place. You may

need to refer to this information sometime in the future.

Parasound A 21 Amplifier Serial #: ____________________

Parasound Dealer: ____________________________________

Phone Number:_______________________________________

Date of Purchase: _____________________________________

YOU SHOULD KNOW

There is no Parasound warranty for this unit if it was not purchased from an Authorized

Parasound Dealer. Investigate any warranty claims made by unauthorized dealers very

carefully as you will need to depend entirely upon the dealer, and NOT upon Parasound.

Unauthorized dealers may lack the capability to arrange repairs of Parasound equipment.

Authorized Parasound Dealers are listed at www.parasound.com or you can call 415-397-7100

between 8:30 am and 4:30 pm Pacific time.

A missing or tampered serial number could indicate that this unit was stolen or sold by an

unauthorized dealer. If this unit is missing its serial number, you should return it to your

dealer immediately for a full refund.

PLACEMENT GUIDELINES FOR YOUR A 21

_________________________________________________________________________________

CONNECTING A STEREO PREAMPLIFIER OR A SURROUND

CONTROLLER TO THE BALANCED INPUTS ON YOUR A 21

_________________________________________________________________________________

CONNECTING A STEREO PREAMPLIFIER OR A SURROUND

CONTROLLER TO THE UNBALANCED INPUTS ON YOUR A 21

_________________________________________________________________________________

CONNECTING THE A 21 LOOP OUT JACKS

TO ANOTHER POWER AMPLIFIER’S INPUTS

_________________________________________________________________________________

CONNECTING SPEAKERS TO YOUR A 21

_________________________________________________________________________________

CONFIGURING THE A 21 FOR BRIDGED MONO OPERATION

_________________________________________________________________________________

MANUAL AND AUTOMATIC TURN ON-OFF OPTIONS

_________________________________________________________________________________

CONNECTING AN EXTERNAL DC SOURCE FOR A 21 AUTOMATIC TURN ON-OFF

_________________________________________________________________________________

CONNECTING THE A 21 TO TRIGGER ANOTHER COMPONENT

_________________________________________________________________________________

UNDERSTANDING THE INDICATORS ON THE A 21

_________________________________________________________________________________

CONNECTING THE A 21 AC POWER CORD

_________________________________________________________________________________

MAINTAINING YOUR A 21

_________________________________________________________________________________

TROUBLESHOOTING GUIDE

_________________________________________________________________________________

SERVICING YOUR A 21

_________________________________________________________________________________

TECHNICALLY SPEAKING

_________________________________________________________________________________

PARASOUND A 21 DESIGN OVERVIEW

_________________________________________________________________________________

PARASOUND A 21 SPECIFICATIONS

_________________________________________________________________________________

TABLE OF CONTENTS

A 21 Amplifier

PLACEMENT GUIDELINES FOR YOUR A 21

Power ampliers are usually heavier and generate more heat than other components. To avoid

damage to the A 21 or other equipment and to reduce risk of re, you must follow these

guidelines:

• Place the A 21 on a separate shelf that will adequately support its weight.

• Keep it away from heat sources such as air ducts or radiators.

• Avoid placing it on carpeting or another material that might obstruct airow into the openings

in the chassis bottom.

• Leave at least 3” of space around both sides and 6” of space above the top. The bottom

clearance can be a little less.

• Do not block the front of the A 21 behind closed cabinet doors during use.

• Do not stack the A 21 with other components inside a cabinet unless you use a fan to circulate

and exhaust the warm air that builds up between them.

Rack Mounting Your Parasound A 21

To mount the A 21 into a 19” wide equipment rack, you must rst attach its rack mount brackets

(provided). With its four feet removed, the A 21 chassis and front panel height occupies four rack

spaces (7” or 176 mm). When mounting equipment below the A 21, you will also need to allow

about 1/8” below the unit for the bottom chassis screws. A single standard rack space allows

1-3/4” vertical height in a 19" wide equipment rack. This measurement standard was developed

by the EIA (Electronic Industries Association) so manufacturers of electronic components and

equipment racks could build products in standardized heights that would t in a uniform space.

Please call your Parasound dealer or Parasound Technical Services if you need additional advice

about rack mounting the A 21.

To attach the rack mount brackets:

• Remove the three screws from each side of the A 21. These are arranged vertically, behind its

front panel and in front of its rst heatsink n.

• Line up the three holes on each bracket with the three holes on the A 21 and reinsert

the screws.

• Make sure the screws are tight because they will support the entire weight of the A 21 in the

equipment rack

HRA-4 Rack Adapter Mounted on JC 1

Rack Mount Brackets Attached to A 21

XLR Connectors

Male

Female

YOU SHOULD KNOW

Balanced XLR Jacks and Their Pin Configuration

The balanced inputs of the A 21 use XLR jacks that conform to the industry standard of:

Pin 1: Ground, Pin 2: Positive (+), Pin 3: Negative (--). The balanced outputs on some

components use terminals with 3 screws instead of XLR jacks. These are compatible with

the A 21 as long as you match the bare wires to the corresponding pins on the XLR plug: +

to pin 2, - to pin 3, and Ground to pin 1.

CONNECTING A STEREO PREAMPLIFIER OR A SURROUND

CONTROLLER TO THE BALANCED INPUTS ON YOUR A 21

3&4

Left

Right

COMPONENTS

SURROUND

SOUND

CONTROLLER

PREAMP

OUTPUTS

1 2

Left and Right Balanced Input Jacks

Balanced connections will give you the best sound. If your preamplifier or surround controller

has balanced XLR output jacks, we recommend that you connect them to these inputs. Refer

to the Balanced and Unbalanced Lines in the Technically Speaking section for additional

information about why we recommend using balanced lines.

What You’ll Need:

• One pair of balanced interconnect cables with XLR connectors

• A preamplifier or surround controller with balanced outputs

Before Connecting

Leave the A 21’s AC cord disconnected until you have made all other connections to

prevent any surprise burst of sound.

Make sure that all your cables are long enough so they are not strained or stretched

once they are connected.

Make sure the Inputs switch on the rear of the A 21 is in its Balanced (up) position and

the Ground switch is in its Normal (down) position.

To Connect

Plug the male end of the balanced interconnect cable into the Balanced Right Channel

input jack on the A 21.

Plug the female end of this cable into the balanced right channel output jack on

your preamplifier (or a channel on your surround controller).

Repeat steps 1 and 2 above to connect the left channel.

Left and Right Unbalanced Inputs

Use these inputs if your preamplifier or surround controller doesn’t have balanced

output connectors or if you simply prefer to use unbalanced connections.

What You’ll Need:

• A pair of shielded interconnect cables with RCA plugs

• A source component with RCA output jacks

Before Connecting

Leave the AC cord on the A 21 disconnected until you have made all other connections

to prevent any surprise burst of sound.

Make sure that all your cables are long enough so they are not strained or stretched

once they are connected.

Make sure the Inputs switch on the A 21 is in its Unbalanced (down) position and the

Ground switch is in its Normal (down) position.

To Connect

Plug one end of the cable into the Unbalanced Right Channel Input jack on the A 21.

Plug the other end of this cable into the unbalanced right channel output jack on your

preamplifier (or a channel on your surround controller).

Repeat steps 1 and 2 for the left channel.

CONNECTING A STEREO PREAMPLIFIER OR A SURROUND

CONTROLLER TO THE UNBALANCED INPUTS ON YOUR A 21

COMPONENTS

SURROUND

SOUND

CONTROLLER

PREAMP

OUTPUTS

Right Left

RCA Plugs

Right

Left

3&4

YOU SHOULD KNOW

Interconnect Cables and Their Color Codes

Common color codes for input and output jacks are red for right and white for left. Match

the colors at the outputs from your preamplifier or surround controller to the inputs on your

A 21 so you’ll always hear the channels in their intended position.

Loop Out Connector

The Right and Left Loop Out jacks provide connections to route the same input signals from

your preamplifier or surround controller to an additional power amplifier. In most instances,

you won't use the loop out feature so you can skip this section.

What You’ll Need:

• One pair of shielded interconnect cables with RCA plugs

• An additional amplifier

Before Connecting

Leave the AC cord on the A 21 disconnected from the wall until you have made all of

the connections in the system to prevent any surprise burst of sound.

Make sure that your interconnect cables are long enough so they are not strained or

stretched once they are connected.

To Connect

Plug one end of the cable to the right channel Loop Out jack on the A 21.

Plug the other end of this cable to the right channel input jack on the other power amplifier.

Repeat steps 1 and 2 for the left channel.

RCA Plugs

Right

Left

CONNECTING THE A 21 LOOP OUT JACKS

TO ANOTHER POWER AMPLIFIER’S INPUTS 4

YOU SHOULD KNOW

These jacks eliminate the need for two “Y” connector cables to split the outputs from the

two source channels between your A 21 and another amplifier. The A 21 Loop Out Jacks

jacks provide the same signals that are received at either the balanced or the unbalanced

inputs. Refer to Loop Out Jacks in the Technically Speaking section for more information

about when to use the Loop Out Jacks.

COMPONENTS

POWER AMP

Right Left

INPUTS

3&4

Stripped

AWG wire

Dual

Banana Plug

Common Speaker Connectors

Single

Banana Plug

Spade Lug

Red usually

designates right

The GND notch

signifies ground

or speaker left

Speaker Terminals

The five-way binding post speaker terminals on the A 21 accept most speaker wire

terminations including single or dual banana plugs, 1/4” spade lugs, or bare wire.

Refer to Bare Wire Speaker Termination in the Technically Speaking section for

information about bare wire termination.

What You’ll Need:

• Two lengths of speaker wire

AWG 16 or thicker with banana

plugs, spade lugs, or bare wire

• Loudspeakers or a speaker

selector box

Before Connecting

Remove power to all the components in your audio system.

To Connect

Insert one wire with the ridge or other marking into the red Right + (positive) speaker

terminal on the A 21. Insert the wire without the ridge or other marking into the black

Right - (negative) speaker terminal on the A 21.

Insert the other end of the wire with the ridge or other marking into the red right +

(positive) terminal on the speaker. Insert the wire without the ridge or other marking

into the black right - (negative) terminal on the speaker.

Repeat steps 1 and 2 for the left channel.

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 both 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.

CONNECTING SPEAKERS TO YOUR A 21

3&4

2 4

1 3

Speakers

CONFIGURING THE A 21 FOR BRIDGED MONO OPERATION 6

YOU SHOULD KNOW

IMPORTANT! - Before Trying Bridged Mono

You should not connect a speaker with an impedance of less than 8 Ω to the A 21 when it is

configured for bridged mono operation. Refer to Bridged Mono Operation in the Technically

Speaking section for additional information about. Use the right channel Gain control to

adjust level in the bridged mode.

Speaker

4 5

RightLeft

Components

Surround

Sound

Controller

Preamp

OUTPUTS

In certain applications, you may require your A 21 to power a single 8

Ω sp

eaker by

using its bridged mono feature. In most instances, you won’t use the A 21 this way and

you can skip this section.

What You’ll Need:

• One length of speaker wire with banana plugs, spade lugs, or bare wires

• One shielded balanced or unbalanced interconnect cable for each A 21 used

in bridged mono

• One loudspeaker with an impedance of 8

Ω

or higher

Before Connecting

Remove power to all the components in your audio system.

Set the A 21 Stereo - Mono Bridge Switch to its Mono (up) position.

To Connect: From the Source

Plug one end of the interconnect cable into the Balanced or Unbalanced Right

Channel & Mono Input jack on the A 21

Plug the other end of this cable into the desired output channel on the preamplifier

or surround controller.

Do not make any connection to either Left Channel Input jack on the A 21.

To Connect: To the Speaker

Insert the wire with the ridge or other marking into the red Right + (positive) speaker

terminal on the A 21. (This is the positive speaker terminal in bridged mono.)

Insert the wire without the ridge or other marking into the Left + (positive) speaker

terminal on the A 21. (This is the negative speaker terminal in bridged mono.)

Insert the wire with the ridge or other marking into the red + (positive) terminal on the speaker.

Insert the wire without the ridge or other marking into the black -- (negative) terminal

on the speaker.

Do not make connections to either of the

A 21's black speaker terminals.

MANUAL AND AUTOMATIC TURN ON-OFF OPTIONS

YOU SHOULD KNOW

Turn Off Delay in the Audio Mode

When the music (audio signal) stops, the A 21 will remain turned on for about five minutes.

This delay prevents unwanted turn-off during silent passages in music or pauses between

1Switch in up position

Start Sensitivity at 12 o'clock

You can manually turn the A 21 on and off with its front panel On-Off button. It can also be

triggered to turn on and off automatically when your preamplifier, surround controller, or

system controller is turned on and off.

Manual On-Off from the Front Panel

If you want to manually turn on and off the A 21 at any time, you need to first select

the Manual On-Off option by placing the Auto Turn On switch (on the rear panel) to

its middle Man (Manual) position.

Connecting an Active Audio Source for Automatic On-Off

If you want to automatically turn on the A 21 whenever music is playing (an audio

signal is present), choose the audio triggering option by moving the Auto Turn On

switch to its upper Audio position.

What You’ll Need:

• An audio source that's playing

Before Connecting

Remove power to all the components in your audio system.

Make sure the Auto Turn On switch on the A 21 is in its Audio (up) position.

Set the Audio triggering Sensitivity adjustment knob on the rear panel to the desired

level. Start with the 12 o’clock position.

To Connect

Connect an active audio source to either the Left or Right Balanced or Unbalanced

Input jacks. (Refer to to pages 2 and 3).

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