OWNER’S MANUAL 400W 4-Channel Amplifier Thank you for purchasing a JL Audio amplifier for your automotive sound system. Your amplifier has been designed and manufactured to exacting standards in order to ensure years of musical enjoyment in your vehicle. For maximum performance, we highly recommend that you have your new amplifier installed by an authorized JL Audio dealer. Your authorized dealer has the training, expertise and installation equipment to ensure optimum performance from this product.
PROTECT YOUR HEARING! We value you as a long-term customer. For that reason, we urge you to practice restraint in the operation of this product so as not to damage your hearing and that of others in your vehicle. Studies have shown that continuous exposure to high sound pressure levels can lead to permanent (irreparable) hearing loss. This and all other high-power amplifiers are capable of producing such high sound pressure levels when connected to a speaker system.
PLANNING YOUR INSTALLATION It is important that you take the time to read this manual and that you plan out your installation carefully. The following are some considerations that you must take into account when planning your installation. Safety Considerations: Your amplifier needs to be installed in a dry, well-ventilated environment and in a manner which does not interfere with your vehicle’s safety equipment (air bags, seat belt systems, ABS brake systems, etc.).
PRODUCT DESCRIPTION The JL Audio RD400/4 is a four-channel, fullrange audio amplifier utilizing JL Audio NexD™ ultra-high speed switching technology to deliver outstanding fidelity and efficiency. The RD400/4 can be operated with a wide variety of source units and system configurations. TYPICAL INSTALLATION SEQUENCE The following represents the sequence for a typical amplifier installation, using an aftermarket source unit or OEM Interface processor (like the FiX™ 82 or FiX™ 86).
CH. 1&2 Ground Remote INPUT SECTION +12 VDC Left or Mono Right Only The RD400/4’s “+12 VDC” and “Ground” connections are designed to accept 4 AWG copper power wire. 4 AWG is the minimum copper wire size for this amplifier. If you are installing the RD400/4 with other amplifiers and wish to use a single main power wire, use 4 AWG, 2 AWG or 1/0 AWG main power wire (depending on the overall current demands of all the amplifiers in the system).
1) +12V remote turn-on lead 2) DC offset-sensing turn-on circuit 3) Signal-sensing turn-on circuit +12V Remote Turn-On: This is the preferred method for turning the amplifier on/off. The amplifier will turn on when +12V is present at its “Remote” input and turn off when +12V is switched off. This +12V remote turn-on signal is typically controlled by a source unit or OEM interface processor’s remote turn-on wire. The RD400/4’s “Remote” turn-on connector will accept 18 AWG – 12 AWG wire.
INPUT SECTION The RD400/4’s input section allows you to send signals to the amplifier section through the use of two or four differential-balanced inputs. Input connections are via two pairs of traditional RCA-type jacks. CH. 1&2 Remote (L) Right Only (R) PREOUTS Ground INPUT SECTION Line output converters are usually not needed Input Sensitivity Input Type Input Sensitivity with the RD400/4.
INPUT SENSITIVITY CONTROLS The control labeled “Input Sensitivity” and “Clipping” LED are used to match the source unit’s output voltage to the input stage of the RD400/4 for maximum clean output. Rotating the control clockwise will result in higher sensitivity (louder for a given input voltage). Rotating the control counter-clockwise will result in lower sensitivity (quieter for a given input voltage).
the “Input Level” switch is in the “High” position, the level of the input signal is attenuated –12 dB to produce a line level signal at the “Preouts”. This ensures a proper line level signal output under both conditions. Tuning Hint: If you are using the RD400/4 to drive a subwoofer system (“LP” mode), a component satellite speaker system (“HP” mode) or both, 80 Hz is a good baseline “Filter Freq. (Hz)” setting.
BRIDGING CONSIDERATIONS Bridging is the practice of combining the output of two amplifier channels to drive a single load. When bridged, each channel produces signals of equal magnitude, but opposite polarity. The combined output of the two channels provides twice the output voltage available from a single channel. The RD400/4 has been designed for bridging of its main channel pairs without the need for Y-adaptors or input inversion adaptors.
If the condition remains, it will return to red and mute the output again. A continuous over-current condition is displayed with alternating red/blue lights. Because the muting behavior may be very short in duration, it may manifest itself as an audible, repetitive ticking or thumping noise in the output. Over-current conditions can be caused by a speaker impedance lower than the optimum load impedance range for the amplifier or a short-circuit in the speaker wiring.
B) F ade Subwoofer Level vs. HF Level Req uired: a source unit or processor with two pairs of stereo outputs. Inp ut Connections: the first stereo pair of source unit outputs is connected to the “CH 1 (Left)” and “CH 2 (Right)” inputs of the RD400/4. The second stereo pair of source unit outputs is connected to the “CH 3 (Left)” and “CH 4 (Right)” inputs (select “4 Ch.” on the “Input Mode” switch).
“Input Sensitivity” settings and will not be user adjustable from the front of the vehicle. B) Subwoofer Level Control Only: Req uired: a source unit or processor with left, right and dedicated subwoofer outputs. Inp ut Connections: The main stereo pair of source unit outputs is connected to the “CH 1 (Left)” and “CH 2 (Right)” inputs of the RD400/4 (select “2 Ch.” on the “Input Mode” switch). The source unit’s dedicated subwoofer output is connected to the subwoofer amplifier inputs.
APPENDIX A: Input Sensitivity Level Setting Follow the steps below to adjust the input sensitivity of each amplifier channel pair, simply and easily, in just a few minutes to achieve overall system balance. Necessary Equipment • CD with a sine-wave test tone recorded at 0 dBfs reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofer channels, 1 kHz for a midrange application). Do not use attenuated test tones (-10 dB, -20 dB, etc.).
APPENDIX B: RD400/4 Specifications Amplifier Section: Amplifier Topology: NexD™ Ultra-High Speed Class D Power Supply: Unregulated MOSFET switching type Rated Power at 14.4V with less than 1% THD+Noise (20 Hz - 20 kHz) RMS Method Stereo, all channels driven: 75W RMS x 4 @ 4 ohms, 100W RMS x 4 @ 2 ohms Bridged, all channels driven: 150W RMS x 2 @ 8 ohms, 200W RMS x 2 @ 4 ohms Rated Power @ 12.
APPENDIX C: TROUBLESHOOTING “How do I properly set the input sensitivity on my amplifier?” Please r efer to Appendix A (page 14) to set the input sensitivity for maximum, low-distortion output. “My amplifier doesn’t turn on.” Check t he fuse, not just visually, but with a continuity meter. It is possible for a fuse to have poor internal connections that cannot be found by visual inspection. It is best to take the fuse out of the holder for testing.
“My amplifier shuts off once in a while, usually at higher volumes.” Check y our voltage source and grounding point. The power supply of the RD400/4 will operate with charging system voltages down to 10V. Shutdown problems at higher volume levels can occur when the charging system voltage (or remote turn-on voltage) drops below 10V. These dips can be of very short duration making them extremely difficult to detect with a common DC voltmeter.
INSTALLATION NOTES: Use this diagram to document your amplifier’s switch and control positions. Turn On Mode Rem. | Offset | Signal +12 VDC 18 | JL Audio - RD400/4 Owner’s Manual Ground Remote Input Voltage Input Mode Low | High 2 Ch. | 4 Ch. Left or Mono CH. 1 CH. 3 Right Only CH. 2 CH.
Input Type Input Sensitivity Stereo | Mono Clipping Input Type Stereo | Mono Filter Mode Filter Mode Off | HP | LP Off | HP | LP CH. 1 (L) CH. 2 (R) Clipping Filter Freq. (Hz) Filter Freq. (Hz) CHANNELS 1 & 2 Input Sensitivity CHANNELS 3 & 4 CH. 3 (L) CH.
LIMITED WARRANTY - AMPLIFIERS (USA) JL AUDIO warrants this product to be free of defects in materials and workmanship for a period of two (2) years. The warranty is extended to three (3) years total if installation is performed by an authorized JL Audio dealer using a JL Audio Premium Power Connection System for power wiring. This warranty is not transferrable and applies only to the original purchaser from an authorized JL AUDIO dealer.
