Boston GT-20 User manual

os ton
T-20
T-22
2-Channel, High-Current/High-Power Amplifiers
Boston
Boston Acoustics

Table of Contents
Parts Lis
Features and Specifications
Control Functions
Control functions (cont.)
Mechanical Functions
Recessed RCA inputs
Control cover removal &reinstallation
Multi-position mounting feet
Vents (side &rear)
Mechanical
functions (cont.)
Amplifier linking
Wire connection
Fuses
General Installation Precautions
Before you install
Battery &
charging system
Wire routing
Installation-Amplifier Mounting
Choose the mounting location
Height, width, and depth diagrams
Installation-amplifier mounting (cont.)
Passenger &
trunk compartment mounting
Installation-Fuses &Wiring
Amplifier fuses
Wire gauge
Installation-fuses & wiring (cont.)
Power/B+ & power/ground (GND) connection
Remote input connection
Speaker output connection
Installation-fuses & wiring (cont.)
Mono subwoofer operation
Setup Tuning-Full-range Speakers
Music
Sensitivity controls
Highpass &lowpass crossover controls
Setup tuning-full-range speakers (cont.)
Head unit
Volume
Input sensitivity control
Crossover controls
Setup tuning-full-range speakers (cont.)
"Q" control
Setup Tuning-Rear Fill Speakers
Setup
Tuning-Subwoofers
Input switch
Setup tuning-subwoofers (cont.)
Head unit
Volume
Input sensitivity control
Lowpass crossover control
Phase
System Examples
Amplifier Troubleshooting Guide
Contact and Warranty Information
2
3
3
4
5
6
6
6
6
6
7
7
7
7
8
8
8
8
9
9
9
10
10
10
10
10
11
11
11
11
12
12
12
12
12
12
13
13
13
13
13
14
14
14
14
14
15
15
15
15
15
15
16,17
18
19

Parts List
Included Hardvvare: GT-20 &GT-22
(1) owner's manual
(1) female quick-connect terminal
(1) 2mm hex wrench (for speaker input)
(1) 3mm hex wrench (for power input)
(4) mounting screws
Features and Specifications
GT-20 &GT-22 Features
2-Channel, High-Current Amplifier
212 Mono Operation
Power Increase with InputVoltage
Rise
Advanced Cooling Allows Varied Mounting Positions
Adjustable Feet
for Varied Mounting Surfaces
Continuously Variable Crossover and
Q-~actor Settings
Selectable Highpass, Lowpass, and Bandpass Settings
Bandpass Configurable
for Midbass or Subwoofer
Terminals
Accept Bare, Heavy-Gauge Wire
Screw-Down Security Cover Protects Tuning Controls
Technical Specifications
GT-20 GT-22
14.4VDC Power
@40hms 2x60W 2x100W
@20hms 2x100W 2x175W
@4 Ohms (mono) 1x200W 1x350W
@2 Ohms (mono) 1x250W 1x500W
12.6VDC Power
@40hms
2x45W 2x75W
@20hms
2x75W 2x135W
@4 Ohms (mono) 1x165W 1x275W
@2 Ohms (mono) 1x230W 1x400W
Freguency Response (-3dB) 10Hz-95kHz 10Hz-95kHz
Signal-to-Noise Ratio (A Weighted) >100dB >100dB
Dimensions (HxWxD) 57x200x225mm
57 x308x225mm
3

Control Functions
............ ···········11··························:········11······ ··············D··· .. ·
11
:,,:1
1
III
~=.= ........
GT-22 Top Panel Shown
<D RCA Inputs
RCA cables from head unit or from other line level device should be connected
here. Use both inputs (L & R) for stereo; use "L" input for mono.
®Remote Input
Use the supplied FEMALE quick-connector to connect the REMOTE trigger lead
from the head unit to the amplifier~ Amplifierturns "ON" when head unit is turned
"ON." One FEMALE .210" connector is supplied with amplifier.
®Input Switch
In the left position, the L&R inputs go to the L&Rchannels of the amplifier. In
the right position, the input is for mono operation.
@InputSensitivity Control
Turn control clockwise to increasethe amplifiersensitivity to incoming signals. Turn
control
counterclockwi~e to'decrease the amplifier sensitivity.
®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.)
4

Control Functions (cont.)
@Lowpass Crossover Controls
To use 12dB/octave crossover/ move switch to right-hand position. Lowpass
crossover
frequency is adjustable from 50Hz to 350Hz by rotary control. (Moving
switch to left-hand position will bypass crossover functions.)
(j) "Q" Control
The IIQII Control is active when the highpass crossover is engaged and is cen-
tered on the selected crossover point. The range of operation is 0.7-1.2.
dB
Q
+1.6dB
OdB -----.,.....~-~~ ... --
-3dB
.707 .95 1.2
t(tuned crossover frequency)
®Status LED Indicators
GREEN indicates the normal operating condition; the amplifier is 1I0N.1I GREEN
and RED together are normal when the amplifier is first turned 1I0NII; 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 afault condition/ IISAFE.
II
5

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 &Reinstallation
The cover panel is secured with two (2) captive coin-slotted screws. Coin-slotted
screws allow acoin edge to be used as ascrewdriver 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 &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 ----f----l~ §§1l3@@[1@[JiJ ii~-- lower side vent
6

Mechanical Functions (cont.) ..
Amplifier Linking
The design of the side panels enables multiple amplifiers to be used together without additional hardware.
fOl fOl fOl fOl
II
rr II
rr
~
~ ~
I<
,.,•
~
~ ~ ~
;);
~ ~
,.,
,, , ,
~
~
)ol
~ It ~.
~
III
<ID
<ID
IIIIII
<ID
<ID
III
~ ~
~ l2J
Wire Connection
Amplifier accepts stripped wire directly into the terminal blocks. Speaker outputs accept8-gauge, and the
DC power and ground accept 4-gauge. Tighten with supplied hexwrenches.
Fuses
Amplifier accepts standard AT-style automotive blade fuses.
GT-20 GT-22
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 vehi-
cle.
Doing so will prevent damage to both the electrical system of the vehicle and the amplifier during
installation.
Battery &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.
8

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 avehicle!
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.
,-..,._L
@13mm 0.5
11
)
IIII
<lD
GT-22
<lD
IIII II~
<ID
GT-20
III
I~
N
N
~
C)
o
N
~
C)
,,
~
Q:O
~
@
~
Darn
0
~po~
0
--.
,...-----,
o
o
200mm (8
11
)------L308mm (12")
T
57mm (2.5
11
)
~
T
57mm (2.5
11
)
~
9

Installation-Amplifier Mounting (cont.)
Passenger &Trunk Compartment Mounting
If the amplifier is mounted under aseat, 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 aseat, 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 atrunk, choose alocation 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 amplifierwith 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 &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.
G1=-20
GT-22
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.
10