Boston Acoustics GT-50 User Manual

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GT-50

5-Channel,High-Current/High-PowerAmplifier

Table of Contents

Parts List

3

Features and Specifications

3

Control Functions

4

Control functions (cont.)

5

Control functions (cont.)

6

Mechanical Functions

6

Control cover removal and reinstallation

6

Multi-positionmounting feet

6

Mechanical functions (cont.)

7

Vents

7

Amplifier linking

7

Wire connection

7

Fuses

7

General Installation Precautions

8

Before you install

8

Battery and charging system

8

Wire routing

8

Installation—AmplifierMounting

9

Choose the mounting location

9

Installation—amplifiermounting (cont.)

10

Passenger and trunk compartment mounting

10

Installation—Fusesand Wiring

10

Amplifier fuses

10

Wire gauge

10

Installation—fusesand wiring (cont.)

11

Power/B+ and power/ground connection

11

Remote input connection

11

Speaker output connection

11

Installation—fusesand wiring (cont.)

12

Mono subwoofer operation

12

Setup Tuning—Full-RangeSpeakers

12

Music

12

Front, rear, and subwoofer sensitivity controls

12

Front, rear, and subwoofer crossover controls

12

Setup tuning—full-rangespeakers (cont.)

13

Head unit

13

Volume

13

Front and rear input sensitivity control

13

Front and rear crossover controls

13

Setup tuning—full-rangespeakers (cont.)

14

Front and rear Q-factoradjustments

14

Rear input sensitivity and crossover controls

14

Setup Tuning—Subwoofers

14

Subwoofer level control

14

Subwoofer mode switch

14

Setup tuning—subwoofers(cont.)

15

Head unit

15

Volume

15

Subwoofer sensitivity control

15

Subwoofer crossover control

15

Phase

15

System Examples

16,17

Amplifier Troubleshooting Guide

18

Contact and Warranty Information

19

2

Parts List

Included Hardware

(1) owner’s manual

(1) female quick-connectterminal for remote input

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

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

(6) mounting screws

Features and Specifications

GT-50Features

5-Channel,High-CurrentAmplifier

2Ω Mono Operation

Advanced Cooling Allows Varied Mounting Positions

Adjustable Feet for Varied Mounting Surfaces

Security Cover Protects Control Settings

Power Increase with Input Voltage Rise

Continuously Variable Crossovers and Q-factorSettings

Selectable Highpass Front and Rear Channels

Discrete Subwoofer Channel Inputs

Selectable 24dB or 12dB Subwoofer Lowpass Setting

Optional Remote Subwoofer Level Control

Enhanced Switching Assignments

GT-50Specifications

14.4VDC Power

Multi-ChannelPower @ 4Ω

4x55W, 1x250W

Multi-ChannelPower @ 2Ω

4x85W, 1x350W

Mixed Op. Power @ 4Ω, 2Ω

4x55W, 1x400W

 

 

12.6VDC power

 

Multi-ChannelPower @ 4Ω

4x45W, 1x190W

Multi-ChannelPower @ 2Ω

4x65W, 1x250W

Mixed Op. Power @ 4Ω, 2Ω

4x45W, 1x300

 

 

Frequency Response (-3dB)

10Hz–95kHz

Signal-to-NoiseRatio (A Weighted)

>100dB

Dimensions

21/4x215/8x87/8” (57 x 548 x 225mm)

3

Control Functions

4

7

4

10

11

9

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

OFF

ON

STEREO

MONO

OFF

ON

STEREO

FRONT

OFF

ON

 

LOWPASS

 

 

 

L+R

 

 

 

+ REAR

 

 

OFF

12dB 24dB

 

HIGHPASS

 

REAR INPUT

 

HIGHPASS

 

MONO

SUBWOOFER LEVEL

 

3 5 0

 

 

 

3 5 0

 

L

 

 

 

3 5 0

 

 

 

 

 

 

 

 

 

2 0 0

Hz

 

 

2 0 0

Hz

 

 

 

 

2 0 0

Hz

 

2 0

 

 

 

2 0

 

 

 

 

 

5 0

0 . 2

1 . 2

0 . 2

1 . 2

0 . 2

L

R

L

R

INPUT SENSITIVITY 2 . 6

V

0 . 9 5

Q/HP

INPUT SENSITIVITY 2 . 6

V

0 . 9 5

Q/HP

 

INPUT SENSITIVITY 2 . 6

V

 

 

REMOTE

5

 

0 . 7

 

5

 

0 . 7

 

 

5

 

SUBWOOFER OUTPUT

 

 

 

REMOTE

 

 

 

REMOTE

SUBWOOFER LEVEL

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

 

3

 

5

 

3

 

5

 

 

3

 

 

STATUS

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

SUBWOOFER OUTPUT

 

L

R

L

R

 

ON

 

 

 

 

 

SAFE

 

 

 

 

 

1

2

12

6

2

8

2

11

1 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.

2 FRONT, REAR, and SUBWOOFER Remote Inputs

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. The remote inputs are all in parallel. Only one is to be used. Use any one of the three remote inputs to turn the amplifier on. Do not connect external 12-voltaccessories to these inputs.

3 FRONT, REAR, and SUBWOOFER Input Sensitivity Controls

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

4 FRONT and REAR Highpass Crossover Controls

To use 12dB/octave crossover, move switch to right-handposition. Highpass crossover frequency is adjustable from 20Hz to 350Hz by rotary control. (Moving switch toleft-handposition will bypass crossover functions.)

FUSE 3 x 30A

B+

B+

GND

GND

 

POWER

 

POWER

 

P OW E R

 

P OW E R

B +

B +

GN D

G N D

1

2

O F F O N

H I G H PA S S

3 5 0

2 0 0 H z

2 0

4

Control Functions (cont.)

5 FRONT and REAR “Q” Controls

“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.

dB

Q

+1.6dB

0dB

-3dB

6 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.

7 REAR Input Switch

In the left (STEREO L-R)position, the L & R inputs go to the REAR L & R channels of the amplifier. In the right (FRONTL-R)position, the inputs are derived from the FRONT channels and sent to the REAR L & R channels of the amplifier.

6

2

FRONT

REAR INPUT

8 SUBWOOFER RCA Inputs

RCA cables marked “subwoofer” from head unit or other line level device should be connected here. Use both inputs (L & R) for dual subwoofer output from head unit. Use left (L) input only when single subwoofer output is to be connected.

9 Lowpass Slope and Crossover Controls

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

LOWPASS SLOPE switch. Lowpass crossover frequencies are

SUBWOOFER LEVEL

 

adjustable from 50Hz to 350Hz by rotary control.

 

8

2

LOWPASS

OFF 12dB 24dB

3 5 0

2 0 0

Hz

5 0

10 SUBWOOFER Mode Switch

Move switch to left position (MONO L-R)when used with L & R subwoofer RCA outputs. Move switch to middle position(L-MONO)when used with single subwoofer RCA outputs. Move switch to right position(NON-FADINGMONO) when subwoofer signal is to be derived from front and rear channels.

MONO

NON - FADING

MONO L MONO

5

Control Functions (cont.)

11 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

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

Mechanical Functions

Recessed RCA Inputs

The input jacks are recessed into the body of the amplifier to provide clearance in tight mounting locations.

1 inch1 inch

Control Cover Removal and Reinstallation

The cover panel is secured with two (2) captive coin-slottedscrews.Coin-slot-ted screws allow a coin edge to be used as a screwdriver to remove the panel.

Multi-positionMounting 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 vehicle wiring harness.

6

Mechanical Functions (cont.)

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

Amplifier Linking

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

GT-50

GT-20

Wire Connection

Amplifier accepts stripped wire directly into the terminal blocks. Speaker outputs accept 8-gauge,and the DC power and ground accept4-gauge.Tighten with supplied hex wrenches.

Fuses

Amplifier accepts standard AT-styleautomotive blade fuses.

FUSE 3 x 30A

7

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 vehicle. 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 professionally 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-levelsignals 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.

8

Installation—AmplifierMounting

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

13mm (1/2”)

225mm (87/8”)

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

OFF

ON

STEREO

MONO

OFF

ON

STEREO

FRONT

OFF

ON

LOWPASS

 

 

 

L+R

 

 

 

+ REAR

 

 

 

 

 

HIGHPASS

 

 

REAR INPUT

 

HIGHPASS

 

 

MONO

SUBWOOFER LEVEL

OFF

12dB 24dB

 

 

 

 

 

 

 

3 5 0

 

 

 

 

350

 

 

L

 

 

350

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2 0 0

Hz

 

 

 

2 0 0

Hz

 

 

 

 

200

Hz

 

 

 

 

 

 

 

2 0

 

 

 

 

20

 

 

 

 

 

50

 

 

 

 

 

 

 

0 .2

 

1. 2

 

 

0. 2

 

1 . 2

 

 

 

0 . 2

L

R

L

R

 

INPUT SENSITIVITY

2 . 6

V

0. 9 5

Q/HP

INPUT SENSITIVITY

2 .6

V

0 .95

Q/HP

 

INPUT SENSITIVITY

2 .6

V

 

 

 

 

 

REMOTE

5

 

0. 7

 

 

5

 

0 .7

REMOTE

SUBWOOFER LEVEL

 

5

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

SUBWOOFER OUTPUT

 

 

 

REMOTE

 

 

 

 

 

FUSE 3 x 30A

B+

B+

GND

GND

 

POWER

 

POWER

GT-50

S TAT U S

FRONT SPEAKER OUTPUT

REAR SPEAKER OUTPUT

SUBWOOFER OUTPUT

POWER

POWER

57mm (21/4”)

 

L

R

L

R

 

B+ B+

GND GND

O N

 

 

 

 

 

 

 

 

S A F E

 

 

 

 

 

 

 

 

548mm (215/8”)

9

Installation—AmplifierMounting (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 sliding 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, doublestick tape, or by wedging into position. Amplifier should be mounted using the movable mounting feet and the provided mounting screws.

Installation—Fusesand Wiring

Amplifier Fuses

Although the amplifier has internal fuses, additional fusing should be provided 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 positive (+) 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 3 x 30A

Wire Gauge

The amplifier accepts up to 4-gaugestripped wire at the DC power and ground input terminals, and4-gaugeis recommended. Wire runs should be kept to the minimum practical length.

10