Summary of the content on the page No. 1
GT-28
GT-24
2-Channel, High-Current/High-Power Amplifiers
Summary of the content on the page No. 2
Table of Contents Parts List 3 Features and Specifications 3 Control Functions 4 Control functions (cont.) 5 Mechanical Functions 6 Recessed RCA inputs 6 Control cover removal and reinstallation 6 Multi-position mounting feet 6 Vents (side and rear) 6 Mechanical functions (cont.) 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 Height,
Summary of the content on the page No. 3
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 Continuously Variable Crossover and Q-factor Settings 2 Ω Mono Operation Selectable Highpass, Lowpass, and Bandpass Settings Power Increase with Input Voltage Rise Bandpass Configurable for Midbass or Subwo
Summary of the content on the page No. 4
Control Functions 3 9 7 6 5 STEREO MONO OFF ON OFF ON OFF ON FUSE 4 x 25A INPUT L SUBWOOFER LEVEL LOWPASS SLOPE LOWPASS HIGHPASS 12dB 12dB 24dB 350 350 ST MONO 200 Hz 185 Hz 50 20 MONO 0.2 1.2 B+ B+ GND GND L R INPUT SENSITIVITY 2.6 0.95 Q/HP 5 0.7 INPUT REMOTE SUBWOOFER LEVEL SPEAKER OUTPUT 12.6–14.4VDC GROUND 4 8 GT-28 Top Panel Shown 1 STATUS MONO 12.6–14.4VDC GROUND B+ B+ GND GND L R 9 ON 10 SAFE 2 GT-28 Front Panel Shown 1 RCA Inputs 1 RCA cables from head unit or from other line level de
Summary of the content on the page No. 5
Control Functions (cont.) 6 OFF ON Lowpass Crossover Controls LOWPASS To use lowpass crossover move LOWPASS switch to righthand position. Lowpass 350 crossover frequency is adjustable from 50Hz to 350Hz by rotary control. (Moving 200 Hz switch to left-hand position will bypass crossover functions.) 50 7 Lowpass Slope Select appropriate crossover slope of 12 or 24dB/octave by moving LOWPASS LOWPASS SLOPE SLOPE switch. 12dB 12dB 24dB ST MONO 8 “Q” Control The “Q” Control is active when the highpas
Summary of the content on the page No. 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. 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 installa- tion obstructions on the mou
Summary of the content on the page No. 7
Mechanical Functions (cont.) Amplifier Linking The design of the side panels enables multiple amplifiers to be used together without additional hardware. 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 4 x 25A FUSE 3 x 20A GT-28 GT-24 7
Summary of the content on the page No. 8
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 pre
Summary of the content on the page No. 9
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. 1 13mm ( /2") 7 225mm (8 /8") GT-28 (GT-24 depth dimensions are the same) 1 57mm (2 /2") 1 57mm (2 /2")
Summary of the content on the page No. 10
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,
Summary of the content on the page No. 11
Installation—Fuses and Wiring (cont.) Power/B+ and Power/GND Connection 5 Strip approximately /8" (16mm) of insulation. The positive (+) power wire is installed into the amplifier terminal marked “B+”. The negative (–) wire 1 / " 4 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
Summary of the content on the page No. 12
Installation—Fuses and Wiring (cont.) Mono Subwoofer Operation When the amplifier is configured for mono operation, 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 MONO L R SPEAKER OUTPUT 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
Summary of the content on the page No. 13
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 co
Summary of the content on the page No. 14
Setup Tuning—Full-Range Speakers (cont.) 8) “Q” Control Once the highpass crossover point has been determined, use the “Q” con- trol to increase the bass information centered around the crossover point. Setting the “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; low- ering the “Q” input sensitivity or raising the highpass crossover
Summary of the content on the page No. 15
Setup Tuning—Subwoofers (cont.) 2) 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. 3) Volume With the chosen musical track playing, turn the head unit volume control
Summary of the content on the page No. 16
6.5LF 6.5LF System Examples System A—Full-Range Front Speakers to ground to ground fuse to + battery terminal fuse to + battery terminal System B—Rear Fill Speakers to ground to ground fuse to + battery terminal fuse to + battery terminal 16 6.5LF 6.5LF
Summary of the content on the page No. 17
System Examples (cont.) System C—Parallel 4 Ω Subwoofers (2 Ω load) to ground to ground fuse to + battery terminal fuse to + battery terminal 4Ω 4Ω 10.5LF 10.5LF System D —Series/Parallel 2 Ω Subwoofers (2 Ω load) mono to ground to ground fuse to + battery terminal fuse to + battery terminal 2Ω 2Ω 2Ω 2Ω 10.5LF 10.5LF 10.5LF 10.5LF 17
Summary of the content on the page No. 18
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
Summary of the content on the page No. 19
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 purcha
