Boston GT-50 Owner's Manual

GT-50

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

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2

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-position mounting 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—Amplifier Mounting 9

Choose the mounting location 9
Installation—amplifier mounting (cont.) 10
Passenger and trunk compartment mounting 10

Installation—Fuses and Wiring 10

Amplifier fuses 10
Wire gauge 10
Installation—fuses and wiring (cont.) 11
Power/B+ and power/ground connection 11
Remote input connection 11
Speaker output connection 11
Installation—fuses and wiring (cont.) 12
Mono subwoofer operation 12

Setup Tuning—Full-Range Speakers 12

Music 12
Front, rear, and subwoofer sensitivity controls 12
Front, rear, and subwoofer crossover controls 12
Setup tuning—full-range speakers (cont.) 13
Head unit 13
Volume 13
Front and rear input sensitivity control 13
Front and rear crossover controls 13
Setup tuning—full-range speakers (cont.) 14
Front and rear Q-factor adjustments 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

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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

3

Parts List

GT-50Specifications

14.4VDC Power
Multi-Channel Power @ 4Ω 4x55W, 1x250W
Multi-Channel Power @ 2Ω 4x85W, 1x350W

Mixed Op. Power @ 4Ω, 2Ω 4x55W, 1x400W

12.6VDC power
Multi-Channel Power @ 4Ω 4x45W, 1x190W
Multi-Channel Power @ 2Ω 4x65W, 1x250W

Mixed Op. Power @ 4Ω, 2Ω 4x45W, 1x300

Frequency Response (-3dB) 10Hz–95kHz
Signal-to-Noise Ratio (A Weighted) >100dB
Dimensions 21/4x215/8x87/8” (57 x 548 x 225mm)

GT-50 Features

5-Channel, High-Current Amplifier
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-factor Settings
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

Features and Specifications

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4

Control Functions

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, 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-volt accessories to these
inputs.

FRONT, REAR, and SUBWOOFER Input Sensitivity Controls

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

FRONT and REAR 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.)

HIGHPASS

OFF

ON

20

350

Hz

200

1

2

1

2

3

4

POWER

B+

B+

POWER

GND

GND

L

R

FRONT SPEAKER OUTPUT

L

R

REAR SPEAKER OUTPUT

SUBWOOFER OUTPUT

ON

SAFE

STATUS

2

1

SUBWOOFER OUTPUT

HIGHPASS

OFF ON

5

0.2

V

INPUT SENSITIVITY 2.6

20

350

Hz

200

REMOTE

POWER

B+

B+

POWER

GND

GND

FUSE 3 x 30A

FRONT SPEAKER OUTPUT

L

R

REAR SPEAKER OUTPUT

L

R

12dB

24dBOFF

LOWPASS

50

350

Hz

200

NO N PR IN TA BL E A RE A

REAR INPUT

STEREO

MONO
L+R

HIGHPASS

OFF

ON

5

0.2

V

INPUT SENSITIVITY 2.6

0.7

1.2

Q/HP

0.95

20

350

Hz

200

REMOTE

MONO

L

FRONT
+ REAR

SUBWOOFER LEVEL

OFF

ON

5

0.2

V

INPUT SENSITIVITY 2.6

0.7

1.2

Q/HP

0.95

REMOTE SUBWOOFER LEVEL

STEREO

3

4

5

12

9

8

7 1110

4

6

3 35

2 2 11

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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.

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 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 (FRONT L-R) position, the inputs are derived from the
FRONT channels and sent to the REAR L & R channels of the amplifier.

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.

Lowpass Slope and Crossover Controls

Select appropriate crossover slope of 12 or 24dB/octave by moving
LOWPASS SLOPE switch. Lowpass crossover frequencies are
adjustable from 50Hz to 350Hz by rotary control.

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 sub-
woofer RCA outputs. Move switch to right position (NON-FADING MONO) when
subwoofer signal is to be derived from front and rear channels.

5

Control Functions (cont.)

L MONO

NON-FADING
MONO

MONO

7

8

6

7

8

10

9

5

(tuned crossover frequency)

0dB

+1.6dB

-3dB

t

1.2.95.707

dB

Q

6

2

REAR INPUT

STEREO

FRONT

7

8

8

2

SUBWOOFER LEVEL

OFF

ON

12dB

24dBOFF

LOWPASS

50

350

Hz

200

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6

Mechanical Functions

Recessed RCA Inputs

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

Control Cover Removal and Reinstallation

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

1 inch 1 inch

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).

12

cover panel

11

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.”

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