GT-28 GT-24
2-Channel, High-Current/High-Power Amplifiers
Table of Contents
Parts List |
3 |
Features and Specifications |
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Control Functions |
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Control functions (cont.) |
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Mechanical Functions |
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Recessed RCA inputs |
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Control cover removal and reinstallation |
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Multi-position mounting feet |
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Vents (side and rear) |
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Mechanical functions (cont.) |
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Amplifier linking |
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Wire connection |
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Fuses |
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General Installation Precautions |
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Before you install |
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Battery and charging system |
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Wire routing |
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Installation—Amplifier Mounting |
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Choose the mounting location |
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Height, width, and depth diagrams |
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Installation—amplifier mounting (cont.) |
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Passenger & trunk compartment mounting |
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Installation—Fuses and Wiring |
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Amplifier fuses |
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Wire gauge |
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Installation—fuses and wiring (cont.) |
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Power/B+ and power/ground (GND) connection |
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Remote input connection |
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Speaker output connection |
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Installation—fuses and wiring (cont.) |
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Mono subwoofer operation |
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Setup Tuning—Full-Range Speakers |
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Music |
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Sensitivity controls |
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Highpass and lowpass crossover controls |
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Setup tuning—full-range speakers (cont.) |
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Head unit |
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Volume |
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Input sensitivity control |
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Crossover controls |
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Setup tuning—full-range speakers (cont.) |
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“Q” control |
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Setup Tuning—Rear Fill Speakers |
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Setup Tuning—Subwoofers |
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Input switch |
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Setup tuning—subwoofers (cont.) |
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Head unit |
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Volume |
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Input sensitivity control |
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Lowpass crossover control |
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Phase |
15 |
System Examples |
16,17 |
Amplifier Troubleshooting Guide |
18 |
Contact and Warranty Information |
19 |
2
Parts List
Included Hardware: GT-28 & GT-24
(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-28 and GT-24 Features
2-Channel, High-Current Amplifier
2Ω Mono Operation
Power Increase with Input Voltage Rise
Advanced Cooling Allows Varied Mounting Positions
Adjustable Feet for Varied Mounting Surfaces
24dB or 12dB Octave Lowpass Setting
Continuously Variable Crossover and Q-factor 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
Optional Remote Subwoofer Level Control
Technical Specifications |
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GT-28 |
GT-24 |
14.4VDC Power |
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@ 4 Ohms |
2x250W |
2x175W |
@ 2 Ohms |
2x450W |
2x275W |
@ 4 Ohms (mono) |
1x900W |
1x550W |
@ 2 Ohms (mono) |
1x1350W |
1x900W |
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12.6VDC Power |
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@ 4 Ohms |
2x200W |
2x120W |
@ 2 Ohms |
2x350W |
2x200W |
@ 4 Ohms (mono) |
1x700W |
1x440W |
@ 2 Ohms (mono) |
1x1100W |
1x750W |
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Frequency Response (-3dB) |
10Hz–95kHz |
10Hz–95kHz |
Signal-to-Noise Ratio (A Weighted) |
>100dB |
>100dB |
Dimensions (HxWxD) |
21/4x215/8x87/8” (57x548x225mm) |
21/4x18x87/8” (57x458x225mm) |
3
Control Functions
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STEREO |
MONO |
OFF |
ON |
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OFF |
ON |
OFF |
ON |
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FUSE 4 x 25A |
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INPUT |
L |
SUBWOOFER LEVEL |
LOWPASS SLOPE |
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LOWPASS |
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HIGHPASS |
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12dB |
12dB 24dB |
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350 |
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350 |
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ST |
MONO |
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200 |
Hz |
185 |
Hz |
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50 |
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20 |
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MONO |
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0.2 |
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1.2 |
L |
R |
B+ |
B+ |
GND |
GND |
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INPUT SENSITIVITY |
2.6 |
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0.95 |
Q/HP |
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I NPUT |
REMOTE |
SUBWOOFER LEVEL |
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0.7 |
SPEAKER OUTPUT |
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12.6–14.4VDC |
GROUND |
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GT-28 Top Panel Shown
1 |
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STATUS |
MONO |
12.6–14.4VDC |
GROUND |
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B+ |
B+ |
GND |
GND |
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L |
R |
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ON |
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SAFE |
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GT-28 Front Panel Shown
1 RCA Inputs |
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RCA cables from head unit or from other line level device should be connected |
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here. Use both inputs (L and R) for stereo; use “L” input for mono. |
2 |
2 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.
3 Input Switch
STEREO MONO
INPUT L
In the left position, the L and R inputs go to the L and R channels of the amplifier. In the right position, the input is for mono operation.
4 Input Sensitivity Control
Turn control clockwise to increase the amplifier sensitivity to incoming signals. Turn control counterclockwise to decrease the amplifier sensitivity.
5 Highpass Crossover Controls
To use 12dB/octave crossover, move HIGHPASS 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.)
0.2
INPUT SENSITIVITY 2.6 
5
OFF ON
HIGHPASS
350
185 |
Hz |
20
4
Control Functions (cont.)
6 Lowpass Crossover Controls
To use lowpass crossover move LOWPASS switch to righthand position. Lowpass crossover frequency is adjustable from 50Hz to 350Hz by rotary control. (Moving switch to left-hand position will bypass crossover functions.)
7 Lowpass Slope
Select appropriate crossover slope of 12 or 24dB/octave by moving LOWPASS SLOPE switch.
8 “Q” Control
The “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
.707 .95 1.2
t (tuned crossover frequency)
9 Subwoofer Level Control Port
SUBWOOFER LEVEL switch should be set to “OFF” when control circuit is not installed, (see optional Subwoofer Level Control owners manual).
10 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.”
OFF ON
LOWPASS
350
200 |
Hz |
50
LOWPASS SLOPE
12dB 12dB 24dB ST MONO
5
Mechanical Functions
Recessed RCA Inputs
The input jacks are recessed into the body of the amplifier to provide clearance in tight mounting locations.
1 inch
1 inch
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 vehicle 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
6
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