Boston Acoustics Car Stereo System GT 42 User Manual

GT-42

4-Channel, High-Current/High-Power Ampliﬁer

Download from Www.Somanuals.com. All Manuals Search And Download.

Parts List

Included Hardware

(1) owner’s manual

(1) female quick-connect terminal for remote input

(1) 2mm hex wrench (for speaker input)

(1) 3mm hex wrench (for power input)

(6) mounting screws

Features and Speciﬁcations

GT-42 Features

4-Channel, High-Current Ampliﬁer

Continuously Variable Crossover and Q-factor Settings

2Ω Bridge Stable (Mono) Operation

Selectable Highpass Front Channels

Power Increase with Input Voltage Rise

Advanced Cooling Allows Varied Mounting Positions

Adjustable Feet for Varied Mounting Surfaces

Security Cover Protects Control Settings

24dB or 12dB Octave Lowpass Setting

Selectable Mono/Stereo Rear or Subwoofer Lowpass

Selectable Rear Channel Signal Derived from Front Channel Input

Optional Remote Subwoofer Control

Enhanced Switching Assignments

GT-42Speciﬁcations

14.4VDC Power

@ 4 Ohms

4x100W

4x150W

2x300W

2x450W

@ 2 Ohms

@ 4 Ohms (mono)

@ 2 Ohms (mono)

12.6VDC Power

@ 4 Ohms

4x75W

@ 2 Ohms

4x120W

2x250W

2x350W

@ 4 Ohms (mono)

@ 2 Ohms (mono)

14.4VDC Multi-channel Power

12.6VDC Multi-channel Power

Frequency Response (-3dB)

Signal-to-Noise Ratio (A Weighted)

Dimensions

2x100W (4 ohm), 1x450W (2 ohm)

2x75W (4 ohm), 1x350W (2 ohm)

10Hz–95kHz

>100dB

2¹/4x21⁵/8x8⁷/8” (57 x 548 x 225mm)

Download from Www.Somanuals.com. All Manuals Search And Download.

Control Functions

STEREO

SEND

INPUT

REAR

OFF

200

STEREO

MONO

OFF

FUSE

25A

FRONT INPUT

HIGHPASS

REAR INPUT

SUBWOOFER LEVEL

LOWPASS SLOPE

12dB 12dB 24dB

MONO

LOWPASS

350

200

MONO

B+

GND

0.2

1.2

0.2

INPUT SENSITIVITY 2.6

REMOTE

0.95

Q/HP

0.7

INPUT SENSITIVITY 2.6

REMOTE

SUBWOOFER LEVEL

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

12.6–14.4VDC

GROUND

N O N P R I N TA B L E A R E A

MONO

12.6–14.4VDC

GROUND

STATUS

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

B+

GND

SAFE

FRONT RCA Inputs

RCA cables marked “FRONT” from head unit or from other line level device

should be connected here. Use both inputs (L & R) for stereo.

FRONT Remote Input

Use the supplied FEMALE quick connector to connect the REMOTE trigger lead

from the head unit to the ampliﬁer. Ampliﬁer turns “ON” when head unit is turned

“ON.” One FEMALE .210" connector is supplied with ampliﬁer.

FRONT Input Switch

In the left position, the L & R inputs go to the FRONT L & R channels of the ampli-

ﬁer. In the right position, the L & R inputs go to the FRONT and REAR L & R chan-

nels of the ampliﬁer.

FRONT and REAR Sensitivity

Turn control clockwise to increase the ampliﬁer sensitivity to incoming signals. Turn

control counterclockwise to decrease the ampliﬁer sensitivity.

FRONT Highpass Crossover Controls

To use 12dB/octave crossover, move switch to right-hand position. Highpass

crossover frequency is adjustable from 20Hz to 350Hz by rotary control. (Moving

switch to left-hand position will bypass crossover functions.)

Download from Www.Somanuals.com. All Manuals Search And Download.

Control Functions (cont.)

“Q” Control

“Q” Control is active when the highpass crossover is engaged and is centered

on the selected crossover point. The range of operation is 0.7–1.2.

+1.6dB

0dB

-3dB

.707 .95 1.2

t(tuned crossover frequency)

REAR RCA Inputs

RCA cables marked “REAR” from head unit or other line level device should be

connected here. Use both inputs (L & R) for stereo.

REAR Remote Input

This remote input is parallel to the FRONT remote input and does not need to

be connected for the ampliﬁer to operate. Use either remote input to turn the

ampliﬁer on. Do not connect 12V accessories to this input.

REAR Input Switch

In the left position, the L & R inputs go to the REAR L & R channels of the ampli-

ﬁer. In the right (MONO) position, the inputs are summed. Use this setting when

the REAR channels are used with a subwoofer.

Lowpass Slope and Crossover Controls

OFF

200

Select appropriate crossover slope of 12 or 24dB/octave by

LOWPASS

moving LOWPASS SLOPE switch. Lowpass crossover fre-

quencies are adjustable from 50Hz to 350Hz by rotary control.

Move ﬁlter switch to “ON” position to engage.

LOWPASS SLOPE

350

12dB 12dB 24dB

MONO

Status LED Indicators

GREEN indicates the normal operating condition; the ampliﬁer is “ON.” GREEN

and RED together are normal when the ampliﬁer is ﬁrst turned “ON”; RED will

turn off after a few seconds. When both GREEN and RED remain on, the ampli-

ﬁer is in thermal shutdown condition. RED only indicates a fault condition, “SAFE.”

Download from Www.Somanuals.com. All Manuals Search And Download.

Control Functions (cont.)

Subwoofer Level Control and Port

Switch should be set to “OFF” when control circuit is not installed,

(see optional “subwoofer level control” owner’s manual).

cover panel

Mechanical Functions

Recessed RCA Inputs

The input jacks are recessed into the body of the ampliﬁer to provide clear-

ance in tight mounting locations.

1 inch

Control Cover Removal and Reinstallation

The cover panel is secured with two (2) captive coin-slotted screws. Coin-slotted

screws allow a coin edge to be used as a screwdriver to remove the panel.

Multi-position Mounting Feet

The mounting feet are designed to slide in both directions to clear installation

obstructions on the mounting surface.

WARNING! Before driving the mounting screws through any surface, be sure

of what is behind that surface. Check for the gas tank, brake lines, and any vehi-

cle wiring harness.

Vents (Side and Rear)

The cooling vents must be kept clear of obstructions once the ampliﬁer is installed. Failure to do this could

lead to premature thermal shutdown or ampliﬁer failure.

upper side vent

lower side vent

Download from Www.Somanuals.com. All Manuals Search And Download.

Mechanical Functions (cont.)

Ampliﬁer Linking

The design of the side panels enables multiple ampliﬁers to be used together without additional hardware.

GT-42

GT-20

Wire Connection

Ampliﬁer accepts stripped wire directly into the terminal blocks. Speaker outputs accept 8-gauge, and the

DC power and ground accept 4-gauge. Tighten with supplied hex wrenches.

Fuses

Ampliﬁer accepts standard AT-style automotive blade fuses.

FUSE

20A

Download from Www.Somanuals.com. All Manuals Search And Download.

General Installation Precautions

WARNING! Before driving the ampliﬁer mounting screws through any surface, be sure of what is behind

that surface. Check for the gas tank, brake lines, and any vehicle wiring harness. Never run wires outside

or under the vehicle or where they could become broken or interfere with the safe operation of the

vehicle.

Before You Install

Before you install the unit, disconnect the negative (–) battery cable in the engine compartment of the vehi-

cle. Doing so will prevent damage to both the electrical system of the vehicle and the ampliﬁer during

installation.

Battery and Charging System

In order for the ampliﬁer to function correctly, the electrical system of the vehicle should be professional-

ly checked for overall electrical capacity. When used, the ampliﬁer will increase the demand on the battery

and alternator. Therefore both should be thoroughly evaluated before installing the ampliﬁer to ensure they

are in normal operating condition and able to handle the increased demand the ampliﬁer will present to

the vehicle’s electrical system.

Wire Routing

Do not run the power wire near any low-level signals or audio cables such as the RCAs from the head

unit. (Noise can be introduced into the ampliﬁer when this occurs.) It is helpful to diagram the wire layout

ﬁrst before any installation is attempted.

Download from Www.Somanuals.com. All Manuals Search And Download.

Installation—Ampliﬁer Mounting

Choose the Mounting Location

Plan your installation so that the ampliﬁer is mounted where adequate ventilation is available.

Never mount an ampliﬁer in the engine compartment of a vehicle!

WARNING! Before driving the mounting screws through any surface, be sure of what is behind that sur-

face. Check for gas tank, brake lines, and any vehicle wiring harness.

13mm (¹/2”)

225mm (8 /8”)

GT-42

STATUS

MONO

12.6–14.4VDC

GROUND

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

B+

GND

57mm (2 /4”)

SAFE

548mm (21 /8”)

Download from Www.Somanuals.com. All Manuals Search And Download.

Installation—Ampliﬁer Mounting (cont.)

Passenger and Trunk Compartment Mounting

If the ampliﬁer is mounted under a seat, be sure that the vents do not become

blocked. Do not allow seat padding or other obstructive material to press

down on the ampliﬁer.

All Boston GT ampliﬁers have top panel controls. If the ampliﬁer is mounted

under a seat, position the ampliﬁer so the cover panel can be removed with

the seat forward or back to allow adjustment of the audio settings.

When mounting in a trunk, choose a location that will be protected from slid-

ing cargo or other materials. Mount the ampliﬁer to solid surfaces only. Do not

mount to plastic trim panels. Do not mount the ampliﬁer with Velcro, double-

stick tape, or by wedging into position. Ampliﬁer should be mounted using

the movable mounting feet and the provided mounting screws.

Installation—Fuses and Wiring

Ampliﬁer Fuses

Although the ampliﬁer has internal fuses, additional fusing should be pro-

vided at the battery on the positive (+) power wire going to the ampliﬁer.

An inline fuse should be installed at no more than 18" (46cm) on the pos-

itive (+) power wire. The rating of the inline fuse should equal the value of

the internal fuses of the ampliﬁer if only the ampliﬁer is connected to this

wire. If other devices are connected to this wire, the fuse value should be

of sufficient capacity to handle the demand.

FUSE

20A

Wire Gauge

The ampliﬁer accepts up to 4-gauge stripped wire at the DC power and ground input terminals, and 4-gauge

is recommended. Wire runs should be kept to the minimum practical length.

Download from Www.Somanuals.com. All Manuals Search And Download.

Installation—Fuses and Wiring (cont.)

Power/B+ and Power/GND Connection

Strip approximately ⁵/8" (16mm) of insulation. The positive (+) power wire

is installed into the ampliﬁer terminal marked “B+.” The negative (–) wire

is installed into the terminal marked “GND.” The ground wire should be

as short as possible and connected directly to the chassis of the vehicle.

Make sure that the chassis connection point is free of rust, grease, dirt,

paint, and other materials that may insulate the ground wire from making

proper connection. Tighten the B+ and GND terminals with the supplied

3mm hex wrench to secure the wire into the terminals. If the power wire

must be routed through a drilled or existing hole, use a nylon panel grom-

met to prevent fraying the wire insulation. Failure to do so could lead to

an electrical short if the wire insulation is worn through and the power wire

is shorted to ground.

¹/₄"

Strip ⁵/8" (16mm)

Remote Input Connection

Use the supplied FEMALE slide connector to connect the REMOTE trig-

ger lead from the head unit to the ampliﬁer. Crimp connector to wire from

head unit that controls remote turn-on (refer to head unit owner’s manu-

al). Once the slide connector is crimped into place, carefully push connector

onto recessed male REMOTE terminal adjacent to the RCA Input pair. Only

one (1) remote turn-on terminal should be connected.

Speaker Output Connection

Prepare each wire by stripping approximately ⁵/8" (16mm) of insulation. The positive (+) speaker wire is

installed into the ampliﬁer terminal marked “SPEAKER OUTPUT” / “+.” The negative (–) speaker wire is

installed into the ampliﬁer terminal marked “SPEAKER OUTPUT” / “-.” Tighten the “Speaker Output”, “+”,

and “-” terminals with the supplied 2mm hex wrench to secure the wire into the terminals. If the speaker

wires must be routed through a drilled or existing hole, use a nylon panel grommet to prevent fraying the

wire insulation. Failure to do so could lead to an electrical short if the wire insulation is worn through and

the speaker wires are shorted to ground.

Download from Www.Somanuals.com. All Manuals Search And Download.

Installation—Fuses and Wiring (cont.)

Mono Subwoofer Operation

If the ampliﬁer is to be bridged and used with a subwoofer connected to the REAR channels, use the

“SPEAKER OUTPUT” terminals marked for mono use.

WARNING! Subwoofer impedance must not fall below 2 ohms when in MONO mode.

2-ohm minimum

Setup Tuning—Full-Range Speakers

1) Music

The material chosen for head unit/ampliﬁer system setup must be both clear in recording quality and dynam-

ic in amplitude. Many audiophile “test” discs have musical tracks with both of these characteristics and should

be used.

2) FRONT and REAR Sensitivity Controls

Turn controls all the way counterclockwise (minimum position). In this position,

the ampliﬁer will be less sensitive to the input signal from the head unit.

3) FRONT and REAR Crossover Controls

Crossovers should be turned off during this phase of set-up. Move the HIGHPASS and FILTER switches to

the “OFF” position—with these settings, full-range signal is sent to the FRONT & REAR speaker outputs.

OFF

200

OFF

185

LOWPASS SLOPE

12dB 12dB 24dB

LOWPASS

350

HIGHPASS

350

MONO

FRONT crossover control

REAR crossover control

Download from Www.Somanuals.com. All Manuals Search And Download.

Setup Tuning—Full-Range Speakers (cont.)

4) Head Unit

The head unit should have all controls such as bass, treble, balance, and fader set to the ﬂat or centered

position. The volume control should be at the minimum setting. If the head unit has any equalization or bass

management features such as boost, they should be defeated at this time. Turn head unit on, and verify

that the GREEN status LED is lit on the ampliﬁer.

5) Volume

With the chosen musical track playing, turn the head unit volume control up until the maximum level of

undistorted signal is heard from the speakers. (For most head units, this will be near the end of the volume

control range.)

WARNING! A distorted signal from the head unit sent to the ampliﬁer can cause loudspeaker failure at high-

er listening levels!

6) FRONT Input Sensitivity Control

Slowly rotate control clockwise until maximum undistorted playing level is

heard from the speakers. Listen closely for bottoming from the speakers. If

detected, rotate FRONT Input Sensitivity counterclockwise until it is eliminated.

7) FRONT Crossover Controls

To achieve higher undistorted playing levels from the front speakers, the

FRONT crossover must be engaged. Rotate crossover control fully clockwise.

The highpass crossover point is now set at 350Hz. Rotate FRONT “Q” Control

fully counterclockwise. Move crossover switch to the right (ON) position.

OFF

185

HIGHPASS

350

Slowly rotate FRONT input sensitivity control clockwise until maximum undis-

torted playing level is heard from the speakers. Listen closely for bottoming

from the speakers. If detected, rotate FRONT input sensitivity control coun-

terclockwise until it is eliminated. Slowly rotate FRONT highpass crossover con-

trol counterclockwise while listening for bottoming. You are lowering the crossover point, which means that

more bass signal is being sent to the speakers. If bottoming is detected, Rotate FRONT input sensitivity

control counterclockwise until it is eliminated and/or rotate the FRONT highpass crossover control clock-

wise to raise the crossover point.

Download from Www.Somanuals.com. All Manuals Search And Download.

Setup Tuning—Full-Range Speakers (cont.)

8) FRONT “Q” Control

Once the FRONT highpass crossover point has been determined, use the

FRONT “Q” control to increase the bass information centered around the

crossover point.

Setting the front “Q” control is done in conjunction with setting the levels on

the input sensitivity and highpass crossover frequency controls. You may ﬁnd

while setting the “Q” that bottoming may be detected in the front speakers;

lowering the “Q” input sensitivity or raising the highpass crossover point will

eliminate this. Minor adjustments to each setting are required to ﬁne-tune the

system.

Setting the “Q” is a subtle process. It is recommended that the “Q” setting be left in the 0.7 position and

adjusted only after the input sensitivity and highpass crossover ranges are known. Small adjustments to the

“Q” setting are all that are required to ﬁne-tune the system.

9) REAR Input Sensitivity and Crossover Controls

OFF

200

Setting levels for the rear channels proceeds the same as for

the front except for the elimination of the “Q” control settings.

Crossover selector switch must be set to “HP” and ﬁlter switch

must be set to “ON.” If the loudspeaker being used is capa-

ble of full-range operation, ﬁlter should be set to “OFF.”

LOWPASS SLOPE

12dB 12dB 24dB

LOWPASS

350

MONO

Setup Tuning—Rear Fill Speakers

You may set the rear channels for summed mono operation from the L & R REAR RCA inputs by setting the

REAR INPUT switch to the right-hand MONO position and then connecting the L & R REAR loudspeakers

normally as you would for regular stereo operation. This conﬁguration is beneﬁcial for rear ﬁll in some appli-

cations.

Setup Tuning—Subwoofers

1) SUBWOOFER LEVEL Control

Refer to subwoofer level control in owner’s manual. If the control is not used, SUBWOOFER LEVEL switch

must be set to “OFF.”

2) REAR Input Switch

Move switch to the right-hand (MONO) position, the inputs are summed to mono. Connect the subwoofer

to the REAR SPEAKER OUTPUT terminals marked for MONO operation. NOTE: Subwoofer impedance is

2 ohms minimum.

Download from Www.Somanuals.com. All Manuals Search And Download.

Setup Tuning—Subwoofers (cont.)

3) Head Unit

The head unit should have all controls such as bass, treble, balance, and fader

set to the ﬂat or centered position. The volume control should be at the

minimum setting. If the head unit has any equalization or bass management

features such as boost, they should be deactivated at this time. Turn head unit

on, and verify that the GREEN status LED is lit on the ampliﬁer.

4) Volume

With the chosen musical track playing, turn the head unit volume control up until the maximum level of

undistorted signal is heard from the speakers. For most head units, this will be at the end of the volume

control range.

WARNING! A distorted signal from the head unit sent to the ampliﬁer can cause loudspeaker failure at

higher listening levels!

5) REAR Input Sensitivity Control

Turn controls all the way counterclockwise (minimum position). In this position, the ampliﬁer will be less sen-

sitive to the input signal from the head unit. Slowly rotate this control clockwise until maximum undistorted

playing level is heard from the subwoofers. Listen closely for faults such as bottoming from the subwoofer.

If fault is detected, rotate REAR input sensitivity control counterclockwise until fault is eliminated. At this

point, the maximum undistorted subwoofer playing level has been deﬁned.

6) REAR Crossover Control

Move the selector switch to “LP” and the FILTER switch to “ON.” In this setting, lowpass signal is sent to

the REAR speaker outputs. Select 12 or 24dB/octave.

7) PHASE

Subwoofer phase is relative to the front loudspeakers. Correct electrical phase does not always mean

correct acoustic phase. Swap positive (+) and negative (-) connections at the speaker outputs where the

subwoofer is connected to the ampliﬁer. It is beneﬁcial to listen to the subwoofer connected in both phase

conditions. The subwoofer should be left in the condition in which the strongest bass response is noted.

Download from Www.Somanuals.com. All Manuals Search And Download.

System Examples

System A—Full-Range Front with Full-Range Rear

to ground

fuse

^to+ battery terminal

System B—Full-Range Front with Rear Fill

to ground

fuse

^to+ battery terminal

fuse

Download from Www.Somanuals.com. All Manuals Search And Download.

System Examples (cont.)

System C—Main Speakers with Single Subwoofer (2Ω)

to ground

fuse

^to+ battery terminal

2Ω

10.5LF

System D —Main Speakers with Parallel 4Ω Subwoofers (2Ω load)

to ground

fuse

^to+ battery terminal

6.5LF

Download from Www.Somanuals.com. All Manuals Search And Download.

Ampliﬁer Troubleshooting Guide

Status LEDs on Ampliﬁer not Lit—Head Unit (Source) Turned “ON”

Verify

Remote turn-on wire from source to ampliﬁer has proper voltage

Power (B+) connections at ampliﬁer, terminal blocks, and battery are secure

Ground (GND) connections at ampliﬁer and vehicle chassis are secure

Battery B+ fuse is OK

Ampliﬁer fuse is OK

B+ at battery and B+ at ampliﬁer have proper voltage

Status LEDs Lit, no Output from Speakers—Speakers in Normal Operating

Condition

Verify

High-level cables from speaker(s) to ampliﬁer are securely connected

RCA cables from ampliﬁer to source are securely connected

Sensitivity adjustment on ampliﬁer is correctly adjusted

Engine Noise from Speaker(s)

Turn source “OFF”

Disconnect RCA cables at ampliﬁer

If noise stops, check equipment & cables leading to ampliﬁer

Verify

RCA cables are of good quality with no breakage to internal shields

RCA cables from source to ampliﬁer are not run alongside power

Ampliﬁer Output Distorted—Music not Recorded with Intentional Distortion

Verify

Source output to ampliﬁer is not distorted

Ampliﬁer input sensitivity is correctly adjusted

Ampliﬁer Shuts Down, Red and Green LEDs are Lit—Ampliﬁer is in Thermal

Protection Mode

Verify

Ampliﬁer is mounted with adequate air circulation around vents

Ampliﬁer does not have obstructions blocking back or side panel vents

Ampliﬁer is not mounted under carpet

Speakers meet correct impedance for application (mono or stereo hookup)

Ampliﬁer Does Not Turn “ON”, and Red LED is Lit—Ampliﬁer not Connected to

a Shorted Speaker

Verify

Speaker crossover is not defective

High-level cables from speaker to ampliﬁer are not shorted

Ampliﬁer Does Not Turn “ON”, and Red LED Lit—Speakers, Crossovers, and

Cable are OK

Ampliﬁer requires service

Download from Www.Somanuals.com. All Manuals Search And Download.

Contact and Warranty Information

Limited Warranty (US)

For one (1) year from the date of purchase, Boston Acoustics will repair for the original owner any defect in materials

or workmanship that occurs in normal use, without charge for parts and labor—when purchased from an authorized

Boston Acoustics retailer.

If an authorized Boston Acoustics retailer installs your ampliﬁer, the warranty will be extended one (1) additional year.

Installation of the ampliﬁer must be noted on the original purchase receipt. The receipt must be presented at the time

a warranty claim is made.

Your responsibilities are to use the system according to the instructions supplied, to provide safe and secure

transportation to an authorized Boston Acoustics service representative, and to present proof of purchase in the form

of your sales slip when requesting service.

Excluded from this warranty is damage that results from abuse, misuse, accidents, shipping, or repairs or modiﬁcations

by anyone other than an authorized Boston Acoustics service representative.

This warranty is void if the serial number has been removed or defaced.

This warranty gives you speciﬁc legal rights, and you may also have other rights that vary from state to state.

If Service Seems Necessary

First, contact the dealer from whom you purchased the ampliﬁer. If that is not possible, write to:

Boston Acoustics, Inc. 300 Jubilee Drive Peabody, MA 01960 U.S.A., or your authorized Boston

Acoustics distributor

We will promptly advise you of what action to take. If it is necessary to return your unit to the factory, please ship it pre-

paid. After it has been repaired, we will return it freight prepaid in the U.S.A. and Canada.

Boston, Boston Acoustics, and the Boston logo are

registered trademarks of Boston Acoustics, Inc.

Speciﬁcations subject to change without notice.

www.bostonacoustics.com

P/N 042-001630-1

300 Jubilee Drive

Peabody, MA 01960 U.S.A.

(978) 538-5000

Download from Www.Somanuals.com. All Manuals Search And Download.

Black Box Computer Accessories gigatrue cat6 component level patch panels User Manual
Black Decker Toaster TRO18 User Manual
Blockhead Video Game Controller BH1101 User Manual
Boss Audio Systems Marine Radio RSD 10 User Manual
BOXLIGHT Projector CD 40m User Manual
Canon Home Security System Vb C50fi User Manual
Casio Cash Register SE S300M User Manual
Casio Watch 2036 1 User Manual
Cateye Bicycle Accessories CC 6000 User Manual
Chevrolet Automobile S 10 User Manual