AMPLIFIER MODELS - Precision Power

AMPLIFIER MODELSDCX 300.4 DCX 600.4DCX 800.5 DCX 1000.4

TABLE OF CONTENTSCongratulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Caution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Fuse Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Amplifier Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5QBASS/QBASS PLUS Specifications . . . . . . . . . . . . . . . . . . . . . .6Tools/Parts for Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Ground Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Charging System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Current Draw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Power Wire Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Power Lock Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Amplifier Bridging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Mixed Mono Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12DCX 300.4 Front Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . .13DCX 300.4 End Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .14DCX 600.4 and DCX 1000.4 Front Plate Diagram . . . . . . . . . . .15DCX 800.5 Front Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . .17DCX 600.4, DCX 800.5, DCX 1000.4 End Plate Diagram . . . . .19Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19DCX 300.4, 600.4, 1000.4 Block Diagram . . . . . . . . . . . . . . . . .20DCX 800.5 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Advanced Instrumentation Input . . . . . . . . . . . . . . . . . . . . . . . . .22QBASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22QBASS PLUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23TC-X Crossover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Crossover Detent Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Input Combine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Adjusting Input Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26High Mass Internal Heatsink . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Forced Air Thermal Management . . . . . . . . . . . . . . . . . . . . . . . .26AP-IV Protection Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281

CONGRATULATIONSThank you for choosing PrecisionPower TM audio equipment.Designed and engineered in the USA, this product combinesinnovative technology with the finest materials to consistently deliverAbsolutely State of the Art performance, sound quality, reliability,and value. This PrecisionPower TM product reflects our commitmentto offer you unparalleled performance and quality for years ofdependable service and listening enjoyment.SERVICEDo not attempt to service PrecisionPower TM products yourself.Performing maintenance on your audio equipment will void thewarranty. Many parts of the PrecisionPower TM product are custombuilt to our specifications. Our factory parts are not madeavailable to anyone else nor are they for sale. Our goal is tomake sure that your PrecisionPower TM product will always sound asgood as the day it was purchased. Contact your AuthorizedPrecisionPower TM Dealer about obtaining any warranty servicethrough PrecisionPower TM . (See the Warranty on the outside of theback cover).CAUTIONExtended use of a high powered audio system may result in hearingloss or damage. While PrecisionPower TM systems are capable of“Concert Level” volumes with incredible accuracy, they are alsodesigned for you to enjoy at more reasonable levels all of the sonicsubtleties created by musicians. Please observe all local soundordinances.2

FEATURESAdvanced Instrumentation Input StageTC-X Crossover 12dB/Octave; HP/LP/FULL; 30-4kHz CrossoverAdaptive PWM Power Supply (DCX 300.4, DCX 600.4, DCX 800.5)AP-IV Protection CircuityFully Regulated PWM Power Supply (DCX 1000.4)Fully Complementary Darlington Output StageForced Air Thermal Management (DCX 1000.4)QBASS TM Bass Boost (DCX 300.4)QBASS Plus TM Bass Boost (DCX 600.4, DCX 800.5, DCX 1000.4)High Voltage Input Capability with -12dB Attention SwitchGold Plated RCA Input and Output ConnectorsPowerLock TM Speaker and Power Wire ConnectorsMixed Mono/Stereo Operation2 Yr Warranty if installed by an Authorized PrecisionPower DealerSPECIFICATIONSPower RatingsMODEL 4ohm STEREO 2ohm STEREO 4ohm MONODCX 300.4 4 X 50 4 X 75 2 X 150DCX 600.4 4 X 75 4 X 150 2 X 300DCX 1000.4 4 X 125 4 X 250 2 X 500DCX 800.5 4 X 50 4 X 100 2 X 2004ohm MONO 2ohm MONO5/Ch. 1 X 200 1 X 400All power ratings given above are tested at 12.5V; 4 ohms; 20Hz - 20kHz.General SpecificationsFrequency Response20Hz - 20kHzPower Bandwidth10Hz - 50 kHzTotal Harmonic Distortion >0.02%S/N Ratio500Slew Rate>20V/µs3

QBASS TMQBASS PLUS TMCrossoversCrossover FrequencyIdle Current:DimensionsUp to +18dB @ 40HzUp to +18dB Boost@30, 36, 44, or 60Hz12dB/Octave30-4kHzDCX 300.4 2 AmpsDCX 600.4 2.5 AmpsDCX 1000.4 3 AmpsDCX 800.5 2.5 AmpsLength Width HeightDCX 300.4 21-½” 10-½” 2-¾”DCX 600.4 24-¾” 10-½” 2-¾”DCX 1000.4 29- 3 /8” 10-½” 2-¾”DCX 800.5 28- 1 /8” 10-½” 2-¾”FUSE REQUIREMENTSYou will need to install an in-line fuse or circuit breaker in the powerwire within 18” of the battery. This fuse or circuit breaker is to protectyour vehicle from fire in case the power wire shorts to the vehiclebody. If you are only using one amplifier, use the fuse ratingindicated in this chart. If you are using more than one amplifier, addup the fuse ratings for all the amplifiers. This sum is the rating foryour fuse or circuit breaker. You may also want to add a powerdistribution block near your amplifiers to distribute large gaugepower cable to multiple amplifiers.AmpDCX 300.4DCX 600.4DCX 1000.4DCX 800.5Fuse50A70A100A100A4

AMPLIFIER STATUS LEDS3 4SHORT PROTECTTHERMAL PROTECTPOWERCLIP OUT1 2The LEDs provide the following indications:1. Power - This LED illuminates RED when the amplifier power isturned on with the remote input (output muted). After a short timedelay this LED will turn GREEN (amplifier ready).2. Clip Output - This LED illuminates RED on the peaks of theoutput signal when the peaks are too high. This clipping causesaudible distortion in the speakers.3. Short - This LED illuminates RED on a short condition. Theamplifier will turn off and try to turn back on.4. Thermal - This LED illuminates RED on a thermal condition. Theamplifier will turn off and turn back on in a minute or so.Note: Read the AP-IV Protection Circuit section for additionalinformation regarding Short and Thermal protection.5

QBASS/QBASS PLUS SPECIFICATIONSQBASS TM (DCX 300.4)Up to 18dB of boost centered at 40Hz, with a Q-factor of 2.QBASS PLUS TM (DCX 600.4, 1000.4, 800.5)Up to 18dB of boost with selectable center frequency at 30Hz, 36Hz,44Hz or 60Hz, with a Q-factor of 2.Optional QBASS REMOTE TM (DCX 600.4, 1000.4, 800.5)This boost control can be mounted in the dash and will supersedethe boost control on the amplifier endplate.TOOLS/PARTS FOR INSTALLATIONNOTE: TOOLS ARE NOT SUPPLIED.Small flat blade screwdriverPhillips screwdriver (#2 or medium sized)Wire cuttersWire strippers4 - #6 round head screws, and 1 - #8 sheet metal screw. (or nut, bolt,flat washer, star washer) (see details)2 - Ring connectors (large enough to accommodate your method ofgrounding)In-line fuse or circuit breakerPower and ground wireSpeaker wire - 12-16 gaugeGrommets (sized to work with the power wire you plan to use in yourinstallation)Tube of silicone sealant6

WIRINGBefore beginning, disconnect the negative (-) terminal of the batteryprior to connecting the amplifier to the positive (+) 12V terminal toprevent a short to ground and potential damage to wiring andequipment. Some vehicle radios have an anti-theft feature wherewhen the radio is removed from 12V the radio will no longer functionand must be code reset.Note: The cables running from the battery to the rear of the carshould be installed on the side of the car opposite to the antenna.When using 16 gauge wire or larger, run the speaker wires from theamplifier location through the vehicle to the speakers. Observe the7

same precautions for routing these wires that you followed forrunning the power and remote turn on wires. Cut off excess and,using wire strippers, strip 1/4-inch of insulation. Locate thespeaker/remote turn-on PowerLock TM connector. Loosen the outerscrews on the underside of the connector. Insert the speaker leadsinto the end. Check to be sure you've maintained proper polaritybefore securing each wire, and plug the PowerLock TM into theamplifier.Note: The power connector is inserted into the amplifier withthe wire clamping screws in the up position as shown below.For the rear channels, locate the four terminal speaker PowerLock TMconnector. (For DCX 800.5, the 5 th channel also uses a four terminalPowerLock TM connector.) On 4 and 5 channel DCX amplifiers, allspeaker PowerLock TM plug into the amplifier with the screws facingup. Loosen the screws on the top of the blocks and insert thestripped ends of the speaker wires into the end. Double checkpolarity, secure each wire by tightening the screws, and plug thePowerLock TM connector into the amplifier with the screws on top.8

GROUND WIRINGLocate an area near the amplifier(s) that is metal and clean an areaabout the size of a quarter down to bare metal. Inspect the areaaround and underneath to be sure you will not drill into wires, brakeor fuel lines, etc. Drill a pilot hole in the middle of this area. Terminatethe ground wire with a ring connector and attach it to the bare metalusing a #8 sheet metal screw and washer or preferable, a bolt, nutand a star washer. (not supplied). We suggest crimping andsoldering this connection. After theconnection is complete, coat the area(on both sides) with silicone or somesimilar material to prevent rust fromdeveloping on the bare metal. If your grand total current draw is over80 amps (or total power is over 500 watts). Keep the ground andpower wires as close together as possible, and use the same gaugewire for both. This will ensure that you have a good ground path, andmay eliminate such potential problems as engine noise andoverheated amplifiers.CHARGING SYSTEMIf your total current draw is over 100 amps (or total output power isover 600 watts), you are probably exceeding the capability of yourcharging system. Dimming lights and fluctuating voltage are solidindicators that you need to upgrade your alternator, battery, or both.You should also check the condition and current capacity of thestock battery negative cable and connections, and replace orupgrade as necessary. Keep in mind that your amplifiers simplyconvert electrical energy to acoustical energy, and any electricaldeficiency will compromise the performance of your sound system.For more information about charging system upgrades, see youlocal authorized PrecisionPower TM Dealer or call PrecisionPower TMTechnical Support at 1-800-62POWER x2033.9

CURRENT DRAWThe following is a basic formula to be used as a guide to determinecurrent draw. Your new DCX amplifier is more efficient than mostother amplifiers. This formula is to be used as a guideline. Using wireof a larger gauge can only improve the current transfer of yoursystem. Do NOT use smaller wire gauge.Total RMS output X 1.5 = Total Input WattageTotal Input Wattage = Current Draw (in Amps)Supply VoltageExample: A DCX amplifier has two channels at 250 watts perchannel RMS rating into 4 ohms (250X2 = 500 watts).You would use the formula in the following way:500 W X 1.5 = 750 watts750W = 62.5 Amps total current draw12VIf the same amplifier is driven into a 2 ohm stereo or 4 ohm monoload, double its 4 ohm RMS rating. All DCX amplifiers will effectivelydouble their power at this load.500W X 1.5 X2 = 1500 watts1500W = 125 Amps total current draw12VIf you are using more than one amplifier, add up the total currentdraw for all of them and choose the appropriate gauge based on thegrand total.10

POWER WIRE SIZEA minimum of 8 gauge or a maximum of 4 gauge wire isrecommended dependent on the application.The ground wire must be the same gauge as the power wire.POWER LOCK CONNECTORSOnce you have run both the power and ground wires, then connectthe cables to the amplifier. Cut off excess wire, and using wirestrippers, strip the ends of the power and ground cablesapproximately 1/4 inch. Locate the PowerLock TM power and groundconnector (supplied). With a small flat blade screwdriver, loosen thescrews before attempting to insert the cable wires. Insert the wiresinto the appropriate hole, and tighten the screws. Once the wires aresecure, the PowerLock TM may be plugged into the amplifier. ThePower/Ground PowerLock TM will accommodate 6 gauge wire for theDCX 300.2 and DCX 600.4, and 4 gauge wire for the DCX 800.5 andDCX 1000.4.AMPLIFIER BRIDGINGPairs of channels in DCX multi-channel amplifiers are capable ofbeing bridged into a 4 ohm mono output without switches or bridging11

modules. This feature permits the creation of a mono channel for asuitable subwoofer or center channel. Deriving the mono channel isaccomplished by using the Left Channel Positive wire (L+) as thepositive speaker wire and the Right Channel Negative wire (R-) asthe negative speaker wire.Note: It is important that a minimum 4 ohm impedance is observed.If the impedance drops below 4 ohms while the amplifier is wired inthe bridged configuration, the amplifier’s protection circuitry mayengage.Note: This does not apply to the DCX 800.5 sub channel, which candrive a 2 ohm load safely.MIXED MONO OUTPUTThe ability to run stereo speakers while simultaneously running amono output from the same amplifier is accomplished by runningthe stereo speakers normally and tapping into the appropriate wiresfor the “mixed mono” channel (left channel positive for the positivespeaker wire and right channel negative for the negative speakerwire). Speaker impedance should be no lower than 2 ohms on thestereo channels and 4 ohms on the mono channel.Note: Passive crossovers must be used for “mixed mono” operation.Choose a low pass crossover around 100Hz for your subwoofer,then choose a high pass crossover for your stereo channels. Thehigh pass crossover must be at the same or slightly higherfrequency than the low pass crossover to maintain the correctimpedance. See your PrecisionPower dealer or call 1-800-62POWER for more information about passive crossovers.12

DCX 300.4 FRONT PLATE DIAGRAMDCX 300.4Front Panel2019181716151413121110FULLLPHPFREQ30 4KOUTPUTSSUMREARLPFULL HPSOURCEFULLLPHPFREQ30 4KGAINMIN MAXREARINT OUTPUT REAREXTRLPFULL HPSOURCEQBASSATTFRONTFULLGAINLPHP30 4KFREQRR- RR+ RL+ RL-BRIDGEDFR- FR+ REM FL+ FL-BRIDGED0 +12dB-12dBLOUTININMIN MAXFRONT1 234 5 6 7 8 91. Cooling Plenums: Maintain a minimum 2” clearance aroundcooling plenums for proper amplifier cooling.2. Rear Speaker Connector: Plug in the PowerLock TM connectorhere.3. Front Speaker/Remote Connector: Plug in the PowerLock TMconnector here.4. QBASS TM Level Control: Controls bass boost, centered at 40Hzwith up to 18dB of boost.5. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltageinput (4V-12V) capability. This button must be pushed ‘IN’ for usewith speaker level input on common ground head-units or for highvoltage line drivers.6. RCA Output: RCA outputs provide HP/LP/FULL 30-4kHz signalto another amplifier.7. Rear Inputs: Plug in the rear RCA leads from your source here.8. Front Inputs: Plug in the front RCA leads from your source here.9. Front Gain: Use this control to match the output level of thesource unit to the front channel of the amplifier.10. Front Freq. Control: Move this detented control in a clockwisedirection to adjust the front crossover frequency from 30Hz to4 kHz.(see Crossover Frequency chart in this manual).11. Front HP/LP/FULL Switch: Select the desired crossoversetting. HP/LP/FULL for the speaker output signal of the frontchannel.12. Rear Input INT/EXT Switch: Select the INT position if you want13

to use the internal signal path from the front crossover for the rearinput, or the EXT position to use the external rear RCA input.13. Source HP/LP/FULL Switch: Select the desired setting.HP/LP/FULL for the internal signal from the front channel to the rearchannel when not using an external rear RCA input.14. Rear Gain: Use this control to match the output level of the headunit to the rear channel of the amplifier.15. Rear Freq. Control: Move this detented control in a clockwiserotation to adjust the rear crossover frequency from 30Hz to 4kHz.(See the Crossover Frequency chart in this manual).16. Rear HP/LP/FULL Switch: Select the desired crossover setting,HP/LP/FULL for the speaker output signal of the rear channel.17. Source Sum/Rear Switch: Select the SUM position if you wantto use the RCA output signal summed from the front and rear audiochannels, or the REAR position to select the input off of the rearchannel only for bandpass capability.18. Source HP/LP/FULL Switch: Select the desired crossoversetting. HP/LP/FULL for the output signal of the rear channel whennot using the SUM source input.19. Output Freq. Control: Use this control to adjust the rear highpass crossover frequency from 30Hz to 4kHz. (See the CrossoverFrequency chart in this manual).20. Output HP/LP/FULL Switch: Select the desired crossoversetting. HP/LP/FULL for the signal of the output RCA.DCX 300.4 END PLATE DIAGRAMDCX 300.4Rear Panel1 21. Power/Ground PowerLock TM : After you have securelyconnected your power and ground wires, plug in the Power/GroundPowerLock TM connector here.14

2. Cooling Plenums: Maintain a minimum 2” clearance aroundcooling plenums for proper amplifier cooling.DCX 600.4 AND DCX 1000.4 FRONT PLATE DIAGRAMDCX 600.4DCX 1000.4Front Panel2120191817161514131211LPFREQLPSUMREARLPFREQGAINLPINTEXTROUTPUTREARFRONTLPFULLHP30 4KOUTPUTSFULLHPSOURCEFULLHP30 4KMIN MAXFULL HPREARSOURCEFREQ QBASS ATTFULLGAINHP30 4KFREQRR- RR+ RL+ RL-BRIDGEDFR- FR+ REM FL+ FL-BRIDGED2 1 -12dBLOUTININMINFRONTMAX1 2 34 5 6 7 8 9 101. Cooling Plenums: Maintain a minimum 2” clearance aroundcooling plenums for proper amplifier cooling.2. Rear Speaker Connector: Plug in the PowerLock TM connectorhere.3. Front Speaker/Remote Connector: Plug in the PowerLock TMconnector here.4 & 5. QBASS TM 1 and QBASS TM 2 Freq.: Use these switches,QBASS TM 1 and QBASS TM 2 to program the QBASS PLUS TM circuitfrequency.6. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltageinput (4V-12V) capability. This button must be pushed ‘IN’ for usewith speaker level input on common ground head-units or for highvoltage line drivers.7. RCA Output: RCA outputs provide HP/LP/FULL 30-4kHz signalto another amplifier.8. Rear Inputs: Plug in the rear RCA leads from your source here.9. Front Inputs: Plug in the front RCA leads from your source inputhere.10. Front Gain: Use this control to match the output level of thesource unit to the front channel of the amplifier.11. Front Freq. Control: Move this detented control in a clockwisedirection to adjust the front crossover frequency from 30Hz to4kHz.12. Front HP/LP/FULL Switch: Select the desired crossover15

setting. HP/LP/FULL for the speaker output signal of the frontchannel.13. Rear Source INT/EXT Switch: Select the INT position (switchin) if you want to use the internal signal path from the front crossoverfor the rear input, or the EXT position (switch out) to use the externalrear RCA input.14. Rear HP/LP/FULL Switch: Select the desired setting.HP/LP/FULL for the internal signal from the front channel to the rearchannel when not using an external rear RCA input.15. Rear Gain: Use this control to match the output level of the headunit to the rear channel of the amplifier.16. Rear Freq. Control: Move this detented control in a clockwiserotation to adjust the rear crossover frequency from 30Hz to 4kHz.17. Rear HP/LP/FULL Switch: Select the desired crossover setting,HP/LP/FULL for the speaker output signal of the rear channel.18. Source Sum/Rear Switch: Select the SUM (switch in position)if you want to use the RCA output information summed from thefront and rear audio channels. Select the REAR (switch out position)to select the input off of the rear channel, providing bandpasscapability.19. Output Source HP/LP/FULL Switch: Select the desiredcrossover setting, HP/LP/FULL for the RCA output signal.20. Output Crossover Freq. Control: Use this control to adjust theoutput crossover frequency from 30Hz to4kHz.21. Output Crossover HP/LP/FULL Switch: Select the desiredcrossover setting, HP/LP/FULL for the internal output signal of theRCA output.Note: See the next section for the rear panel view of this endplate.16

DCX 800.5 FRONT PLATE DIAGRAM12DCX 800.5Front Panel2120 19 18 171615141311109FREQGAINSUMSUBFREQGAININTEXTFULL/LP/HPFREQGAINSUB REAR FRONTRQBASS FREQFULL/LP/HP30 4K MIN MAXSUBSOURCEFULL/LP/HP30 4K MIN MAXREARSOURCEFULL/LP/HPFRONT30 4KMIN MAXSOURCE2 1ATT- - + +SUBRR- RR+ RL+ RL-BRIDGEDFR- FR+ REM FL+ FL-BRIDGED-12dBINININL123456781. Cooling Plenums: Maintain a minimum 2” clearance aroundcooling plenums for proper amplifier cooling.2. Sub Speaker Connector: Plug in the PowerLock TM connectorhere.3. Rear Speaker Connector: Plug in the PowerLock TM connectorhere.4. Front Speaker/Remote Connector: Plug in the PowerLock TMconnector here.5. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltageinput (4V-12V) capability. This button must be pushed ‘IN’ for usewith speaker level input on common ground head-units or for highvoltage line drivers.6. Sub Input: Plug in the front RCA leads from your source unithere.7. Rear Inputs: Plug in the rear RCA leads from your source here.8. Front Inputs: Plug in the front RCA leads from your source inputhere.9. QBASS TM 1 and QBASS TM 2 Freq.: Use these switches,QBASS TM 1 and QBASS TM 2 to program the QBASS PLUS TM circuitfrequency.10. Front Gain: Use this control to match the output level of thesource unit to the front channel of the amplifier.11. Front Freq. Control: Move this detented control in a clockwisedirection to adjust the front crossover frequency from 30Hz to4kHz.17

12. Front HP/LP/FULL Switch: Select the desired crossoversetting. HP/LP/FULL for the speaker output signal of the frontchannel.13. Rear Input INT/EXT Switch: Select the INT position if you wantto use the internal signal path from the front crossover for the rearinput, or the EXT position to use the external rear RCA input.14. Rear Source INT/EXT Switch: Select the INT position (switchin) if you want to use the internal signal path from the front crossoverfor the rear input, or the EXT position (switch out) to use the externalrear RCA input.15. Rear Gain: Use this control to match the output level of the headunit to the rear channel of the amplifier.16. Rear Freq. Control: Move this detented control in a clockwiserotation to adjust the rear crossover frequency from 30Hz to 4kHz.17. Rear HP/LP/FULL Switch: Select the desired crossover setting,HP/LP/FULL for the speaker output signal of the rear channel.18. Sub Source INT/EXT Switch: Select the INT position if youwant to use the internal signal path from the rear crossover for thesub input, or the EXT position to use the external sub RCA input.19. Sub Gain: Use this control to match the output level of the headunit to the sub channel of the amplifier.20. Sub Freq. Control: Use this control to adjust the sub high passcrossover frequency from 30Hz to 4kHz.21. Sub HP/LP/FULL Switch: Select the desired crossover setting,HP/LP/FULL for the internal output signal of the sub channel to thespeaker output.18

ejectVOLUMEBASSLEFTBALANCETREBLERIGHT1 2 3 456FOWARD7TRACK8REVERSEPPI MAR KET ING DPTDCX 600.4, DCX 800.5, DCX 1000.4 END PLATE DIAGRAMDCX 600.4, 800.5, 1000.4Rear Panel1 2 3 4QBASSQBASSREMOTE0 +161. Power/Ground PowerLock TM : After you have securelyconnected your power and ground wires, plug in the Power/GroundPowerLock TM connector here.2. QBASS REMOTE TM : Plug in the data cable from the optionalQBASS REMOTE TM dash mounted level control here. (The remotelevel control will bypass the amplifier’s on board QBASS TM control.3. QBASS PLUS TM : Up to 18dB of bass level control boost.4. Cooling Plenums: Maintain a minimum 2” clearance aroundcooling plenums for proper amplifier cooling.INPUTSThere are two sets of RCA jacks on the front end of your amplifier.The RCA cables from your source unit go in the set labeledINPUTS. If your source unit doesn’t have RCA outputs, then add aset of RCA plugs (available at your dealer) to your front or rear setof speaker leads (see drawing below). Plug them into the inputjacks, and push in the -12dB input attenuation switch.SOURCE HeadunitTrk 1(+) PositiveLEFT input(-) Negative(+) PositiveRIGHT input(-) Negative19

DCX 300.4, 600.4, 1000.4 BLOCK DIAGRAMINPUT ATTENUATIONINPUT ATTENUATION20

DCX 800.5 BLOCK DIAGRAM21

ADVANCED INSTRUMENTATION INPUTThe Advanced Instrumentation Input has been incorporated fromthe legendary PrecisionPower TM 2500F1. This circuit completelyisolates the chassis ground from the audio circuit of the amplifierand reduces noise radiated into your signal cables by up to 40dB.This is equivalent to a noise reduction of approximately one hundredtimes what the noise level would be without this circuitry. It providesall the benefits of a true balanced line without the need of anyspecial cables (see diagram below). This type of input works withany conventional RCA cables.QBASSFor extra BOOM from yoursystem, we’ve developed theQBASS TM bass control circuit.The QBASS TM control islocated on the end platepanel, and allows you to addup to 18dB of boost centeredat 40Hz by rotating the control clockwise.22

QBASS PLUSOn DCX 600.4, DCX 800.5, and DCX 1000.4 amplifiers, we’ve takenbass control to a higher level with QBASS PLUS TM . The twoQBASS TM switches (labeled 1 and 2) on the front end of the amplifierallow you to select one of four frequency centers 30Hz, 36Hz, 44Hzand 60Hz. On the rear end plate you will find the QBASS TM levelcontrol and plug-in for an optional QBASS REMOTE TM dashmounted level control. Adjust the level control clockwise for up to+18dB of boost at your selected frequency.QBASS TM Settings1 2 Freq.IN IN 30HzIN OUT 36HzOUT IN 44HzOUT OUT 60HzCAUTION: QBASS PLUS TM should only be used in systems with astrong subwoofer section. +18dB is a tremendous amount of bassboost and may damage your speakers or create excessive distortionif abused.The optional QBASS REMOTE TM : This boost control can bemounted in the dash and will supersede the boost control on theendplate.The PrecisionPower DCX TM amplifiers no longer need an optionalQPORT TM to connect multiple QBASS PLUS TM equipped amplifierswhile using one QBASS REMOTE TM . The new QBASS PLUS TMcircuitry in the DCX amplifiers is now positioned before thecrossover circuit. In doing this, PrecisionPower TM engineers haveallowed you to daisy chain your RCA output to the next amplifierinput, causing the first amplifier’s QBASS REMOTE TM to become themaster control amplifier. See your authorized PrecisionPower TMdealer for more information!TC-X CROSSOVER23

Your new DCX amplifier has a TC-X Crossover (Total Control X-over ® ) 30Hz-4kHz (see this guide for Crossover Chart).12dB peroctave phase correlated crossover built-in to provide superiorsystem flexibility without the added expense and installation of anoutboard crossover. The speaker outputs of your amplifier are highpass, low pass, or all-pass according to the HP/LP/FULL switch onthe front endplate. You would choose low pass (middle position ofswitch) to use this amplifier for subwoofers, choose high pass (leftposition of switch), or full (right position of switch) to use thisamplifier for full range speakers.The RCA outputs are controlled by a separate HP/LP/FULL switch,and are always independent of the speaker output crossover. Aswell as being able to independently select HP/LP/FULL, your newDCX amplifier allows independent selection of frequencies from30Hz-4kHz (see Crossover Detent Chart in this guide).DCX 300.4/600.4/1000.4Front - 12dB/Octave, Detented High Pass 30Hz-4kHzRear - 12dB/Octave, Detented High Pass; HP/LP/FULLRCA Outputs - 12dB/Octave, Detented High Pass; HP/LP/FULLQBASS PLUS TM - on Rear Channel - up to 18dB @ 30, 36, 44, 60HzDCX 800.5Front - 12dB/Octave, Detented High Pass 30Hz-4kHzRear - 12dB/Octave, Detented High Pass; HP/LP/FULLRCA Outputs - 12dB/Octave, Detented; HP/LP/FULLSub-Summed Stereo - 12dB/Octave Detented; 30Hz-4kHz;HP/LP/FULLQBASS PLUS TM - on Sub Channel - up to 18dB @ 30, 36, 44, 60Hz24

25CROSSOVER DETENT CHARTDetent #Low PassFrequency (Hz)@ -3dBHigh PassFrequency (Hz)@ -3dB123456789101112131415161718192021222324252627282930313233343536373839404128283030303234363842465052546066768810011613614416819824028631034038042448457663274893210761428170024362830298052525256566064727680889210011613214816819221624428434840446851256462470080093210361144130015041812219628404116454047284728

INPUT COMBINEYour multi-channel DCX amplifier can use both front and rearoutputs from your head unit to maintain the ability to fade front torear, or you can run a single set of RCAs to the front inputs and pushin the Rear Input INT/EXT switch on the amplifier endplate to routethe front signal to the rear channels as well.ADJUSTING INPUT GAIN1. Adjust all amplifier input gain controls to just above minimumsensitivity (fully counterclockwise).2. Using the cleanest music source (CD) playing, turn up the headunit source volume until you can hear distortion. Now turn it down abit until you cannot hear the distortion (usually just below fullvolume).3. Increase the amplifier gain (clockwise) until the onset of audibledistortion. Then decrease the gain to the point just before thedistortion starts. This setting minimizes background noise andprevents overload.4. Repeat step 3 for any remaining independently controlledamplifiers (rear and subwoofer gain controls) in the system.HIGH MASS INTERNAL HEATSINKThe unique heatsink on your DCX amplifier has been designed withfins on the inside of the aluminum extrusion. This allows for thetransfer of heat from the circuitry to the heatsink fins and out throughthe vents in the endplates. Be sure you provide ample space aroundthe amplifier for cooling: at least 2” on all sides.FORCED AIR THERMAL MANAGEMENTTo manage the additional heat associated with higher outputcapability, a thermally controlled fan has been designed into theDCX 1000.4. When the heatsink temperature reaches a predeterminedvalue, the fan is activated and cool air is drawn in26

through the lower intake vents on the endplate. This cool air flowsbelow the circuit board, through the fan and across the internal fins,cooling the heatsink. The warm air is then forced out through theupper end-plate exhaust vents.AP-IV PROTECTION CIRCUITShort Circuit Protection engaged: The DCX amplifiers will turn offand try to come back on immediately (the Short RED LED willilluminate). The amplifier will cycle like this indefinitely with “blips” ofsound each time. If this is the case, check your speakers and wiringfor low impedance and short circuits.Thermal Protection engaged. The DCX amplifiers will turn off andafter a minute or so will come back on (the Thermal RED LED willilluminate). In this case, ensure that there is nothing blocking thenormal convection airflow of the amplifier. No obstruction should bewithin 2” of the amplifier on all sides.Note: Low battery voltage will cause the amplifier to runwarmer and possibly damage the amplifier.27

TROUBLESHOOTINGNO SOUND Is the LED illuminated?YESNOCheck Power and Remoteturn-on wire for voltage.Make sure the ground wireis secure.STILL NO SOUNDSee your Authorized PrecisionPower TM Dealer or call 1-800-62POWER.SOUND IN ONE CHANNEL ONLYReverse the left and right speakers by unplugging the speaker connector,turning it over and plugging it back in.SOUND IS NOW INOPPOSITE CHANNELReverse RCA inputs.SAME CHANNELProblem is in the speaker orspeaker wire of the silentchannel.SOUND IS NOW INOPPOSITE CHANNELSAME CHANNELReverse RCA inputs Problem is in the amplifier.at head unit.See your local AuthorizedPrecisionPower Dealer orcall 1-800-62POWER.SOUND IS NOW INOPPOSITE CHANNELSAME CHANNELProblem is in the head Problem is in the RCAunit or before the amplifier. cables.28

LIMITED TWO YEAR CONSUMER WARRANTY:Directed Electronics, Inc. promises to the original purchaser, to replace thisproduct should it prove to be defective in workmanship or material under normaluse, for a period of two years from the date of purchase by the dealer as indicatedby the date code marking of the product PROVIDED the product was installed byan authorized Directed dealer. During this two-year period, there will be no chargefor this replacement PROVIDED the unit is returned to Directed, shipping prepaid.If the unit is installed by anyone other than an authorized Directed dealer,the warranty period will be 1 year from the date of purchase by the dealer asindicated by the date code marking of the product. During this 1-year period therewill be no charge for this replacement PROVIDED the unit is returned to Directed,shipping pre-paid. This warranty is non-transferable and does not apply to any unitthat has been modified or used in a manner contrary to its intended purpose, anddoes not cover damage to the unit caused by installation or removal of the unit.This warranty is void if the product has been damaged by accident orunreasonable use, neglect, improper service or other causes not arising out ofdefects in materials or construction. ALL WARRANTIES INCLUDING BUT NOTLIMITED TO EXPRESS WARRANTY, IMPLIED WARRANTY, WARRANTY OFMERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE, ANDWARRANTY OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY AREEXPRESSLY EXCLUDED TO THE MAXIMUM EXTENT ALLOWED BY LAW,AND DIRECTED NEITHER ASSUMES NOR AUTHORIZES ANY PERSON TOASSUME FOR IT ANY LIABILITY IN CONNECTION WITH THE SALE OF THEPRODUCT. DIRECTED HAS ABSOLUTELY NO LIABILITY FOR ANY AND ALLACTS OF THIRD PARTIES INCLUDING ITS AUTHORIZED DEALERS ORINSTALLERS. Unit must be returned to Directed, postage pre-paid, with:consumer’s name, telephone number, and address, authorized dealer’s name andaddress, and product description. IN ORDER FOR THIS WARRANTY TO BEVALID, YOUR UNIT MUST BE SHIPPED WITH PROOF OF INSTALLATION BYAN AUTHORIZED DIRECTED DEALER. ALL UNITS RECEIVED BY DIRECTEDFOR WARRANTY REPAIR WITHOUT PROOF OF DIRECTED DEALERINSTALLATION WILL BE COVERED BY THE LIMITED 1-YEAR PARTS ANDLABOR WARRANTY. Note: This warranty does not cover labor costs for theremoval and reinstallation of the unit. BY PURCHASING THIS PRODUCT, THECONSUMER AGREES AND CONSENTS THAT ALL DISPUTES BETWEEN THECONSUMER AND Directed SHALL BE RESOLVED IN ACCORDANCE WITHCALIFORNIA LAWS IN SAN DIEGO COUNTY, CALIFORNIA.© 2004 Directed Electronics, Inc. All rights reserved. G48235/40/45/55 01-04