User manual JBL GTQ200

[. . . ] 7 5. 1 Speaker-Level Input Impedance Adjustments . 12 Owner's Warranty Information Model Number Serial Number Dealer Name City, State, Zip Sales Receipt Number Date of Purchase 2 1. Introduction 1. 1 Thanks for purchasing your new GT series automotive multi-channel amplifier. Your GT series amplifier will easily connect to virtually any car audio system, whether it is factory installed or purchased separately. [. . . ] Put the switch in the "GR 2" position to drive Group 2 with the Group 2 inputs. Power Indicator LED (on amp chassis top) ­ LED steadily illuminates for normal operation. LED blinks when protection circuitry or muting is engaged. 3. System Design Using the GTQ200 and GTQ240 3. 1 Speaker Requirements When used in the non-bridged mode, a group-channel of the GTQ200 or GTQ240 can easily drive two 2-ohm speaker loads. When only one speaker is connected to the left and right outputs of a group, virtually any conventional speaker may be used. Although the amplifier will not be damaged, load impedances lower than 2 ohms will eventually cause the amplifier to overheat, activating the protection circuits and causing the unit to shut off until it cools down sufficiently. When a group is in bridged mode, the combined impedance of the speaker (or speakers) connected to the bridged channels should be at least 4 ohms. Sustained operation of the unit in bridged mode with less than 4 ohms will likely cause overheating. The GTQ200 or GTQ240 must not be used with speakers that have either one of their input terminals wired to the frame of the speaker or to the chassis of the vehicle. 4 4. 3 Remote-In/Out Connection 4. Wiring 4. 1 Wiring 3. 2 Signal Sources The low-level preamp outputs of any radio/tape deck, CD player, or preamp/ equalizer so equipped can drive the GTQ200 or GTQ240. The gain controls of the amplifier are used to match its input sensitivity to the output voltage of the source. This will provide the lowest distortion operation from the speaker outputs of most modern head units by reducing the power the amplifier in the head unit must deliver to practically, nothing. On some older or lowerpriced head units this load will not facilitate proper fader operation. To allow for this, we have provided the ability to change the input impedance of the speaker-level inputs to 15 ohms. This is accomplished by moving the jumpers shown on the diagram below. This input is also capable of directly accepting signals, when in the 100k ohm setting, from many Balanced Line Drivers such as those sometimes used in competition vehicles. If the head unit has 4 channels of built-in amplification and/or an electronic fader control, you should leave the jumpers in the factory-set position. If the head unit has 2 channels of amplification, with a speaker-level fader, the jumpers should be set to the 15-ohm position. This will always be a rotary-type control, not one controlled by electronic pushbuttons. JUMPER SELECTOR SELECT 100K OR 15 OHMS 5. 2 Crossover Frequency Adjustments The GTQ amplifiers include built-in frequency selectable crossovers. One crossover is connected in series with the amplifier circuitry and the other crossover is connected to the preamp level output jacks. These crossovers can be set in either the "F" (full bandwidth operation), "L" (subwoofer operation), or "H" (satellite operation). The crossover frequencies are set by chips inside the amplifier. [. . . ] · Incorrect gain adjustment; verify that the amplifier gain controls are not turned completely down. If they are, sound output level may be very low and may give the impression that the system (or part of the system) is dead. Power light is on, but no sound is heard from some or all of the speakers · Defective head unit or signal processor; check each component for proper wiring and operation. · Defective GTQ amplifier; if there is audio signal present at the inputs of the amplifier and there is no output, the GTQ amplifier may be defective. Alternator whine through the audio system with the engine running · Ground loops; follow the wiring suggestions in the section called "Solving Noise Problems. " Also, verify that the chassis grounding point you have chosen is true ground by checking for continuity between the chassis ground point and battery ground. [. . . ]