User manual AKAI GX-F77 SERVICE MANUAL

[. . . ] If not installed by an authorized dealer, Directed Audio power amplifiers are covered by a one-year, parts-andlabor limited warranty. Be sure to retain your original sales receipt and refer to the warranty section of this guide for full details about your coverage. TABLE OF CONTENTS Limited Two-year Consumer Warranty . . 12 Parallel Synced Gain Connections/Settings . . 13 External Synced Bridged Connections/Settings . [. . . ] Due to the high-frequency MOSFET switching power supply, filtering the power cable is not generally required (remember that the amp can't deliver full output if the power supply is restricted). Proper grounding of the signal source is mandatory for the amplifier to reach its performance peak. If the RCA inputs are not grounded adequately via the signal source, electrical noise from the vehicle may be picked up in the system. 6 © 2004 Directed Electronics, Inc FRONT PANEL CONNECTIONS/CONTROLS 1. RCA Input Jacks - Accepts line level outputs from head units or signal processors at voltages between 150mV and 7. 5 volts. RCA Line Output Jacks - These pass through RCA jacks can be used to send the input signal to a second amplifier. Slave/Master Switch (D1200/GX-F77 only) - Controls whether the amplifier is a slave or master when connected in combined amplifier configurations. (Refer to the Combined Amplifiers section of this guide. ) 4. Gain Control - Controls the amplifier's sensitivity and is used to match the input level of the amplifier to the output level of the signal source. Subsonic Switch - The subsonic filter attenuates frequencies below 30Hz by 24dB per octave. Bass EQ Switch - Adds 8dB of bass boost to the subwoofer when selected. Remote - Controls the subwoofer amplifier gain, from a remote location for ease of adjustment during listening. Warning: DO NOT connect a level control knob from other manufacturers to the Remote Sub Level Control of any Directed amplifier. This allows the master amplifier to control gain, filter, and sub-level on both amplifiers. This combination allows the amplifiers to drive their own separate subwoofer(s) while being synced together via an inphase audio pre-amp signal from the master amplifier. Wiring connections to the amplifier subwoofer outputs in this combination should be standard in-phase configurations, creating a parallel speaker connection. (Refer to Parallel Synced Gain section of this guide for amplifier and speaker connection diagrams. ) In this master/slave combination the master amplifier pre-amp controls remain active and the slave amplifier pre-amp is bypassed. This allows the master amplifier to control gain, filter, and sub-level on both amplifiers. This combination allows the amplifiers to drive common subwoofer loads while being synced together via an out-of-phase audio pre-amp signal from the master amplifier. Make sure that each amplifier sees the same speaker impedance. WARNING: The amplifier's gain control is bypassed completely in SLAVE mode. Do NOT move the MASTER/SLAVE switch to SLAVE position when the amplifier is connected and playing. Do NOT connect any signal source to the amplifier in SLAVE mode that exceeds 200mV. 3. Phase Switch - Set the phase switches of all synced amps to the same position (all at 0° or all at 180°). © 2004 Directed Electronics, Inc 13 FIGURE 5--PARALLEL SYNC GAINED D1200/GX-F77 MASTER AMPLIFIER INPUT LINE OUT MASTER SLAVE 0° PHASE 180° R L INPUT LINE OUT MASTER SLAVE 0° PHASE 180° R L SLAVE AMPLIFIER Subwoofer Wiring (top view) MASTER SLAVE NOTE: The dual + and -- sub-out terminals of the D1200/GX-F77 are paralleled internally and the combined load impedance should be taken into consideration when connecting multiple subwoofers. 14 © 2004 Directed Electronics, Inc EXTERNAL SYNCED BRIDGED CONNECTIONS/SETTINGS 1. Input Signal - Connect these RCA jacks as described in the Front Panel Connection section of this guide. [. . . ] Try and keep the setting low enough to prevent image smearing (you should not be able to hear male voices from the subwoofer) but not so low as to create a gap between the subwoofer and the mid-bass/midrange speakers. It will be to your advantage to spend some extra time with this adjustment, listening to familiar music or system set-up discs to achieve the kind of musical reproduction that you prefer. The gain adjustment allows you to set proper signal match for clean, quiet amplifier operation. Start by playing some music you are familiar with. [. . . ]