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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.

6) FRONT Input Sensitivity Control

Slowly rotate control clockwise until maximum undistorted playing level is heard
from the speakers. Listen closely for bottoming from the speakers. If detect-
ed, rotate FRONT Input Sensitivity counterclockwise until it is eliminated. 

7) FRONT Crossover Controls

To achieve higher undistorted playing levels from the front speakers, the FRONT
crossover must be engaged. Rotate crossover control fully clockwise. The high-
pass crossover point is now set at 350Hz. Rotate FRONT “Q” Control fully coun-
terclockwise. Move crossover switch to the right (ON) position. 

Slowly rotate FRONT input sensitivity control clockwise until maximum undis-
torted playing level is heard from the speakers. Listen closely for bottoming from
the speakers. If detected, rotate FRONT input sensitivity control counter-
clockwise until it is eliminated.  Slowly rotate FRONT highpass crossover con-
trol counterclockwise while listening for bottoming. You are lowering the
crossover point, which means that more bass signal is being sent to the speakers. If bottoming is detect-
ed, Rotate FRONT input sensitivity control counterclockwise until it is eliminated and/or rotate the FRONT
highpass crossover control clockwise to raise the crossover point.

5) Volume

With the chosen musical track playing, turn the head unit volume control up until the maximum level of 
undistorted signal is heard from the speakers. (For most head units, this will be near the end of the volume 
control range.)

WARNING!

A distorted signal from the head unit sent to the amplifier can cause loudspeaker failure at high-

er listening levels!

GT-40_manual  4/10/03  4:17 PM  Page 13

Summary of Contents for GT-40

Page 1: ...GT 40 Status On Safe 4 Channel High Current High Power Amplifier GT 40_manual 4 10 03 4 17 PM Page 1...

Page 2: ...round connection 11 Remote input connection 11 Speaker output connection 11 Installation fuses wiring cont 12 Mono subwoofer operation 12 Setup Tuning Full range Speakers 12 Music 12 Front rear sensit...

Page 3: ...ponse 3dB 10Hz 95kHz Signal to Noise Ratio A Weighted 100dB Dimensions 21 4x141 8x87 8 57 x 358 x 225mm GT 40 Features 4 Channel High Current Amplifier 2 Bridge Stable Operation Power Increase with In...

Page 4: ...s go to the FRONT L R channels of the ampli fier In the right position the L R inputs go to the FRONT and REAR L R chan nels of the amplifier FRONT and REAR Sensitivity Turn control clockwise to incre...

Page 5: ...right MONO position the inputs are summed Use this setting when the REAR channels are used with a subwoofer REAR Crossover Controls To use highpass 12dB octave crossover move left switch to upper posi...

Page 6: ...bstructions 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 har...

Page 7: ...r 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 s...

Page 8: ...ectrical 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...

Page 9: ...entilation 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...

Page 10: ...o position Amplifier should be mounted using the movable mounting feet and the provided mounting screws Installation Fuses Wiring Installation Amplifier Mounting cont Amplifier Fuses Although the ampl...

Page 11: ...d FEMALE slide connector to connect the REMOTE trig ger lead from the head unit to the amplifier Crimp connector to wire from head unit that controls remote turn on refer to head unit owner s manu al...

Page 12: ...discs have musical tracks with both of these characteristics and should be used 2 FRONT REAR Sensitivity Controls Turn controls all the way counterclockwise minimum position In this position the ampli...

Page 13: ...ol fully coun terclockwise Move crossover switch to the right ON position Slowly rotate FRONT input sensitivity control clockwise until maximum undis torted playing level is heard from the speakers Li...

Page 14: ...ty Crossover Controls Setting levels for the rear channels proceeds the same as for the front except for the elimination of the Q control settings Crossover selector switch must be set to HP and filte...

Page 15: ...nnections at the speaker outputs where the subwoofer is connected to the amplifier It is beneficial to listen to the subwoofer connected in both phase conditions The subwoofer should be left in the co...

Page 16: ...l range Front with Full range Rear 6 5LF 6 5LF fuse to battery terminal to ground 6 5LF 6 5LF System B Full range Front with Rear Fill 6 5LF 6 5LF fuse to battery terminal to ground 6 5LF 6 5LF GT 40_...

Page 17: ...ers with Single Subwoofer 2 System D Main Speakers with Parallel 4 Subwoofers 2 load 6 5LF 6 5LF 10 5LF 2 fuse to battery terminal to ground 6 5LF 6 5LF fuse to battery terminal to ground 10 5LF 4 10...

Page 18: ...to amplifier Verify RCA cables are of good quality with no breakage to internal shields RCA cables from source to amplifier are not run alongside power Amplifier Output Distorted Music not Recorded w...

Page 19: ...system according to the instructions supplied to provide safe and secure transportation to an authorized Boston Acoustics service representative and to present proof of purchase in the form of your s...

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