Precision Power DCX 1000.4, DCX 800.5, DCX 300.4, DCX 600.4 User Manual

AMPLIFIER MODELS

DCX 300.4 DCX 600.4
DCX 800.5 DCX 1000.4

TABLE OF CONTENTS

Congratulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Caution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Fuse Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Amplifier Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

QBASS/QBASS PLUS Specifications . . . . . . . . . . . . . . . . . . . . . .6

Tools/Parts for Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Ground Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Charging System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Current Draw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Power Wire Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Power Lock Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Amplifier Bridging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Mixed Mono Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

DCX 300.4 Front Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . .13

DCX 300.4 End Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .14

DCX 600.4 and DCX 1000.4 Front Plate Diagram . . . . . . . . . . .15

DCX 800.5 Front Plate Diagram . . . . . . . . . . . . . . . . . . . . . . . . .17

DCX 600.4, DCX 800.5, DCX 1000.4 End Plate Diagram . . . . .19

Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

DCX 300.4, 600.4, 1000.4 Block Diagram . . . . . . . . . . . . . . . . .20

DCX 800.5 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Advanced Instrumentation Input . . . . . . . . . . . . . . . . . . . . . . . . .22

QBASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

QBASS PLUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

TC-X Crossover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Crossover Detent Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Input Combine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Adjusting Input Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

High Mass Internal Heatsink . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Forced Air Thermal Management . . . . . . . . . . . . . . . . . . . . . . . .26

AP-IV Protection Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

1

CONGRATULATIONS

Thank you for choosing

PrecisionPower

TM

audio equipment.
Designed and engineered in the USA, this product combines
innovativ e technology with the finest materials to consistently deliver

Absolutely State of the Art

™

performance, sound quality, reliability,

and value. This

PrecisionPower

TM

product reflects our commitment
to offer you unparalleled performance and quality for years of
dependable service and listening enjoyment.

SERVICE

Do not attempt to service

PrecisionPower

TM

products yourself.
Performing maintenance on your audio equipment will void the
warranty. Many parts of the

PrecisionPower

TM

product are custom
built to our specifications. Our factory parts are not made
available to anyone else nor are they for sale. Our goal is to
make sure that your

PrecisionPower

TM

product will always sound as

good as the day it was purchased. Contact your

Authorized

PrecisionPowerTMDealer

about obtaining any warranty service

through

PrecisionPower

TM

. (See the Warranty on the outside of the

back cover).

CAUTION

Extended use of a high powered audio system may result in hearing
loss or damage. While

PrecisionPower

TM

systems are capable of
“Concert Level” volumes with incredible accuracy, they are also
designed for you to enjoy at more reasonable levels all of the sonic
subtleties created by musicians. Please observe all local sound
ordinances.

2

FEATURES

Advanced Instrumentation Input Stage

TC-X Crossover

12dB/Octave;HP/LP/FULL; 30-4kHz Crossover

Adaptive PWM Power Supply

(DCX 300.4, DCX 600.4, DCX 800.5)

AP-IV

Protection Circuity

Fully Regulated PWM Power Supply

(DCX 1000.4)

Fully Complementary Darlington Output Stage
Forced 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 Switch
Gold Plated RCA Input and Output Connectors

PowerLock

TM

Speaker and Power Wire Connectors
Mixed Mono/Stereo Operation
2 Yr Warranty if installed by an Authorized

PrecisionPower

Dealer

SPECIFICATIONS

Power Ratings

MODEL 4ohm STEREO 2ohm STEREO 4ohm MONO

DCX 300.4 4 X 50 4 X 75 2 X 150
DCX 600.4 4 X 75 4 X 150 2 X 300
DCX 1000.4 4 X 125 4 X 250 2 X 500
DCX 800.5 4 X 50 4 X 100 2 X 200

4ohm MONO

2ohm MONO

5/Ch. 1 X 200 1 X 400

All power ratings given above are tested at 12.5V; 4 ohms; 20Hz - 20kHz.

General Specifications

Frequency Response 20Hz - 20kHz
Power Bandwidth 10Hz - 50 kHz
Total Har monic Distor tion >0.02%
S/N Ratio <110dB
Input Topology Instrumentation
Input Sensitivity 150mV - 12 Volts RMS

(with -12dB pad)
Input Impedance 40 kOhms
Load Impedance (stereo) 2 - 8 Ohms
Load Impedance (bridged) 4 - 8 Ohms
Supply Voltage 11 - 16 Volts
Damping Factor >500
Slew Rate >20V/µs

3

QBASS

TM

Up to +18dB @ 40Hz

QBASS PLUS

TM

Up to +18dB Boost

@30, 36, 44, or 60Hz
Crossovers 12dB/Octave
Crossover Frequency 30-4kHz
Idle Current: DCX 300.4 2 Amps

DCX 600.4 2.5 Amps

DCX 1000.4 3 Amps

DCX 800.5 2.5 Amps

Dimensions

Length Width Height

DCX 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 REQUIREMENTS

You will need to install an in-line fuse or circuit breaker in the power
wire within 18” of the battery .This fuse or circuit breaker is to protect
your vehicle from fire in case the power wire shorts to the vehicle
body. If you are only using one amplifier, use the fuse rating
indicated in this chart. If you are using more than one amplifier, add
up the fuse ratings for all the amplifiers. This sum is the rating for
your fuse or circuit breaker. You may also want to add a power
distribution block near your amplifiers to distribute large gauge
power cable to multiple amplifiers.

Amp Fuse
DCX 300.4 50A
DCX 600.4 70A

DCX 1000.4 100A

DCX 800.5 100A

4

5

AMPLIFIER STATUS LEDS

The LEDs provide the following indications:

1. Power - This LED illuminates RED when the amplifier power is
turned on with the remote input (output muted). After a short time
delay this LED will turn GREEN (amplifier ready).

2. Clip Output - This LED illuminates RED on the peaks of the
output signal when the peaks are too high. This clipping causes
audible distortion in the speakers.

3. Short - This LED illuminates RED on a short condition. The
amplifier will turn off and try to tur n back on.

4.Thermal - This LED illuminates RED on a thermal condition. The
amplifier will turn off and turn back on in a minute or so.

Note: Read the AP-IV Protection Circuit section for additional
information regarding Short and Thermal protection.

POWER CLIP OUT

SHORT PROTECT THERMAL PROTECT

1 2

3 4

QBASS/QBASS PLUS SPECIFICATIONS

QBASS

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 supersede
the boost control on the amplifier endplate.

TOOLS/PARTS FOR INSTALLATION

NOTE:TOOLS ARE NOT SUPPLIED.

Small flat blade screwdriver
Phillips screwdriver (#2 or medium sized)
Wire cutters
Wire strippers
4 - #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 of
grounding)
In-line fuse or circuit breaker
Power and ground wire
Speaker wire - 12-16 gauge
Grommets (sized to work with the power wire you plan to use in y our
installation)
Tube of silicone sealant

6

WIRING

Before beginning, disconnect the negative (-) terminal of the battery
prior to connecting the amplifier to the positive (+) 12V terminal to
prevent a short to ground and potential damage to wiring and
equipment. Some vehicle radios have an anti-theft feature where
when the radio is removed from 12V the r adio will no longer function
and must be code reset.

Note: The cables running from the battery to the rear of the car
should be installed on the side of the car opposite to the antenna.

When using 16 gauge wire or larger, run the speaker wires from the
amplifier location through the vehicle to the speakers. Obser ve the

7

same precautions for routing these wires that you followed for
running the power and remote turn on wires. Cut off excess and,
using wire strippers, strip 1/4-inch of insulation. Locate the
speaker/remote turn-on

Po werLock

TM

connector. Loosen the outer
screws on the underside of the connector. Inser t the speaker leads
into the end. Check to be sure you've maintained proper polarity
before securing each wire, and plug the

Po werLock

TM

into the

amplifier.

Note: The power connector is inserted into the amplifier with
the wire clamping screws in the up position as shown below.

For the rear channels, locate the f our terminal speaker

Po werLock

TM

connector.(For

DCX 800.5

, the 5thchannel also uses a four terminal

Po werLock

TM

connector.) On 4 and 5 channel

DCX

amplifiers, all

speaker

Po werLock

TM

plug into the amplifier with the screws facing
up. Loosen the screws on the top of the blocks and insert the
stripped ends of the speaker wires into the end. Double check
polarity, secure each wire by tightening the screws, and plug the

Po werLock

TM

connector into the amplifier with the screws on top.

8

GROUND WIRING

Locate an area near the amplifier(s) that is metal and clean an area
about the size of a quarter down to bare metal. Inspect the area
around and underneath to be sure you will not drill into wires, brake
or fuel lines, etc.Drill a pilot hole in the middle of this area.Terminate
the ground wire with a ring connector and attach it to the bare metal
using a #8 sheet metal screw and washer or preferable, a bolt, nut
and a star washer. (not supplied). We suggest crimping and

soldering this connection. After the
connection is complete, coat the area
(on both sides) with silicone or some

similar material to prevent rust from
developing on the bare metal.If your grand total current dr a w is o v er
80 amps (

or total power is over 500 watts

). Keep the ground and
power wires as close together as possible , and use the same gauge
wire for both.This will ensure that y ou ha v e a good ground path, and
may eliminate such potential problems as engine noise and
overheated amplifiers.

CHARGING SYSTEM

If your total current draw is over 100 amps (

or total output power is

over 600 watts

), you are probably exceeding the capability of your
charging system. Dimming lights and fluctuating voltage are solid
indicators that you need to upgrade your alternator, battery, or both.
You should also check the condition and current capacity of the
stock battery negative cable and connections, and replace or
upgrade as necessary. Keep in mind that your amplifiers simply
convert electrical energy to acoustical energy, and any electrical
deficiency will compromise the performance of your sound system.
For more information about charging system upgrades, see you
local authorized

PrecisionPower

TM

Dealer or call

PrecisionPower

TM

Technical Suppor t

at

1-800-62POWER x2033

.

9

CURRENT DRAW

The following is a basic formula to be used as a guide to determine
current draw. Your new

DCX

amplifier is more efficient than most
other amplifiers.This f ormula is to be used as a guideline.Using wire
of a larger gauge can only improve the current transfer of your
system. Do NOT use smaller wire gauge.

Total RMS output X 1.5 = Total Input Wattage
T

otal Input Wattage

= Current Draw (in Amps)

Supply Voltage

Example:

A DCX

amplifier has two channels at 250 watts per

channel RMS rating into 4 ohms (250X2 = 500 watts).
You would use the formula in the following way:

500 W X 1.5 = 750 watts
750W

= 62.5 Amps total current draw

12V

If the same amplifier is driven into a 2 ohm stereo or 4 ohm mono
load, double its 4 ohm RMS rating.All

DCX

amplifiers will effectively

double their power at this load.

500W X 1.5 X2 = 1500 watts
1500W

= 125 Amps total current draw

12V

If you are using more than one amplifier, add up the total current
draw f or all of them and choose the appropriate gauge based on the
grand total.

10

POWER WIRE SIZE

A minimum of 8 gauge or a maximum of 4 gauge wire is
recommended dependent on the application.

The ground wire must be the same gauge as the power wire.

POWER LOCK CONNECTORS

Once you have run both the power and ground wires, then connect
the cables to the amplifier. Cut off excess wire, and using wire
strippers, strip the ends of the power and ground cables
approximately 1/4 inch. Locate the

PowerLock

TM

power and ground
connector (supplied). With a small flat blade screwdriver, loosen the
screws before attempting to insert the cable wires. Inser t the wires
into the appropriate hole, and tighten the screws.Once the wires are
secure, the

PowerLock

TM

may be plugged into the amplifier. The

Power/Ground

PowerLock

TM

will accommodate 6 gauge wire for the

DCX 300.2

and

DCX 600.4

, and 4 gauge wire for the

DCX 800.5

and

DCX 1000.4

.

AMPLIFIER BRIDGING

Pairs of channels in

DCX

multi-channel amplifiers are capable of

being bridged into a 4 ohm mono output without switches or bridging

11

modules.This feature permits the creation of a mono channel for a
suitable subwoofer or center channel. Deriving the mono channel is
accomplished by using the Left Channel Positive wire (L+) as the
positive speaker wire and the Right Channel Negative wire (R-) as
the 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 in
the bridged configuration, the amplifier’s protection circuitry may
engage.

Note: This does not apply to the DCX 800.5 sub channel, which can
drive a 2 ohm load safely.

MIXED MONO OUTPUT

The ability to run stereo speakers while simultaneously running a
mono output from the same amplifier is accomplished by running
the stereo speakers normally and tapping into the appropriate wires
for the “mixed mono” channel (left channel positive for the positive
speaker wire and right channel negative for the negative speaker
wire). Speaker impedance should be no lower than 2 ohms on the
stereo channels and 4 ohms on the mono channel.

Note: Passive crossov ers must be used for “mix ed mono”operation.
Choose a low pass crossover around 100Hz for your subwoofer,
then choose a high pass crossover for your stereo channels. The
high pass crossover must be at the same or slightly higher
frequency than the low pass crossover to maintain the correct
impedance. See your

PrecisionPower

dealer or call

1-800-

62POWER

for more information about passive crossovers.

12

DCX 300.4

FRONT PLATE DIAGRAM

1. Cooling Plenums: Maintain a minimum 2” clearance around

cooling plenums for proper amplifier cooling.

2. Rear Speaker Connector: Plug in the

Po werLock

TM

connector

here.

3. Front Speaker/Remote Connector: Plug in the

Po werLock

TM

connector here.

4.

QBASS

TM

Level Control: Controls bass boost, centered at 40Hz

with up to 18dB of boost.

5. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltage
input (4V-12V) capability. This button must be pushed ‘IN’ for use
with speaker level input on common ground head-units or for high
voltage line drivers.

6. RCA Output: RCA outputs provide HP/LP/FULL 30-4kHz signal
to 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 the

source unit to the front channel of the amplifier.

10. Front Freq. Control: Move this detented control in a clockwise
direction 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 crossover
setting. HP/LP/FULL for the speaker output signal of the front
channel.

12. Rear Input INT/EXT Switch: Select the INT position if you want

FREQ

LP

FULL

HP

30 4K

OUTPUTS

LP

FULL

HP

SOURCE

SUM
REAR

LP

FULL

HP

FREQ

30 4K

LP

FULL

HP

GAIN

MIN MAX

REAR

SOURCE

INT
EXT

QBASS

ATT

OUTPUT REARRFRONT

LP

FULL HP

GAIN

ININOUT

L

RR- RR+ RL+ RL-

BRIDGED

FR- FR+ REM FL+ FL-

BRIDGED

0 +12dB

-12dB

MIN MAX

FRONT

FREQ

30 4K

1 6 7 8 9

54

1011

32

121314151617181920
DCX 300.4
Front Panel

13

to use the internal signal path from the front crossover for the rear
input, 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 rear
channel when not using an external rear RCA input.

14. Rear Gain: Use this control to match the output level of the head
unit to the rear channel of the amplifier.

15. Rear Freq. Control: Move this detented control in a clockwise
rotation 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 want
to use the RCA output signal summed from the front and rear audio
channels, or the REAR position to select the input off of the rear
channel only for bandpass capability.

18. Source HP/LP/FULL Switch: Select the desired crossover
setting. HP/LP/FULL for the output signal of the rear channel when
not using the SUM source input.

19. Output Freq. Control: Use this control to adjust the rear high
pass crossover frequency from 30Hz to 4kHz. (See the Crossover
Frequency chart in this manual).

20. Output HP/LP/FULL Switch: Select the desired crossover
setting. HP/LP/FULL for the signal of the output RCA.

DCX 300.4

END PLATE DIAGRAM

1. Power/Ground

PowerLock

TM

: After you have securely

connected your power and ground wires, plug in the Power/Ground

PowerLock

TM

connector here.

DCX 300.4
Rear Panel

1 2

14

2. Cooling Plenums: Maintain a minimum 2” clearance around
cooling plenums for proper amplifier cooling.

DCX 600.4 AND DCX 1000.4

FRONT PLATE DIAGRAM

1. Cooling Plenums: Maintain a minimum 2” clearance around

cooling plenums for proper amplifier cooling.

2. Rear Speaker Connector: Plug in the

Po werLock

TM

connector

here.

3. Front Speaker/Remote Connector: Plug in the

Po werLock

TM

connector here.

4 & 5. QBASS

TM

1 and QBASSTM2 Freq.: Use these switches,

QBASSTM1

and

QBASSTM2

to program the

QBASS PLUS

TM

circuit

frequency.

6. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltage
input (4V-12V) capability. This button must be pushed ‘IN’ for use
with speaker level input on common ground head-units or for high
voltage line drivers.

7. RCA Output: RCA outputs provide HP/LP/FULL 30-4kHz signal
to 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 input

here.

10. Front Gain: Use this control to match the output level of the
source unit to the front channel of the amplifier.

11. Front Freq. Control: Move this detented control in a clockwise
direction to adjust the front crossover frequency from 30Hz to4kHz.

12. Front HP/LP/FULL Switch: Select the desired crossover

LP

FULL HP

GAIN

MIN MAX

FRONT

FREQ

30 4K

OUTPUT REARRFRONT

ININOUT

L

LP

FULL

HP

FREQ

30 4K

LP

FULL

HP

GAIN

MIN MAX

REAR

SOURCE

INT
EXT

QBASS ATT

2 1

-12dB

FREQ

FR- FR+ REM FL+ FL-

BRIDGED

BRIDGED

RR- RR+ RL+ RL-

FREQ

LP

FULL

HP

30 4K

OUTPUTS

LP

FULL

HP

SOURCE

SUM
REAR

1112131415161718192021

1 7 8 9 10

5432 6

DCX 600.4
DCX 1000.4
Front Panel

15

setting. HP/LP/FULL for the speaker output signal of the front
channel.

13. Rear Source INT/EXT Switch: Select the INT position (switch
in) if you want to use the internal signal path from the front crossover
for the rear input, or the EXT position (s witch out) to use the e xternal
rear 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 rear
channel when not using an external rear RCA input.

15. Rear Gain: Use this control to match the output level of the head
unit to the rear channel of the amplifier.

16. Rear Freq. Control: Move this detented control in a clockwise
rotation 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 the
front and rear audio channels.Select the REAR (switch out position)
to select the input off of the rear channel, providing bandpass
capability.

19. Output Source HP/LP/FULL Switch: Select the desired
crossover setting, HP/LP/FULL for the RCA output signal.

20. Output Crossover Freq. Control: Use this control to adjust the
output crossover frequency from 30Hz to4kHz.

21. Output Crossover HP/LP/FULL Switch: Select the desired
crossover setting, HP/LP/FULL for the internal output signal of the
RCA output.

Note: See the next section for the rear panel view of this endplate.

16

DCX 800.5

FRONT PLATE DIAGRAM

1. Cooling Plenums: Maintain a minimum 2” clearance around

cooling plenums for proper amplifier cooling.

2. Sub Speaker Connector: Plug in the

Po werLock

TM

connector

here.

3. Rear Speaker Connector: Plug in the

Po werLock

TM

connector

here.

4. Front Speaker/Remote Connector: Plug in the

Po werLock

TM

connector here.

5. -12dB Attenuation Switch: Push this switch ‘IN’ for high voltage
input (4V-12V) capability. This button must be pushed ‘IN’ for use
with speaker level input on common ground head-units or for high
voltage line drivers.

6. Sub Input: Plug in the front RCA leads from your source unit
here.

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 input

here.

9. QBASS

TM

1 and QBASSTM2 Freq.: Use these switches,

QBASSTM1

and

QBASSTM2

to program the

QBASS PLUS

TM

circuit

frequency.

10. Front Gain: Use this control to match the output level of the
source unit to the front channel of the amplifier.

11. Front Freq. Control: Move this detented control in a clockwise
direction to adjust the front crossover frequency from 30Hz to4kHz.

SUB REAR FRONT

INININ

R

L

QBASS FREQ

-12dB

2 1

GAIN

MIN MAX

FREQ

30 4K

ATT

SOURCE

FRONT

FULL/LP/HP

FULL/LP/HP

INT
EXT

SOURCE

GAIN

MIN MAX

FREQ

30 4K

REAR

FULL/LP/HP

GAIN

MIN MAX

FREQ

30 4K

SOURCE

FULL/LP/HP

SUB

SUM
SUB

FR- FR+ REM FL+ FL-

BRIDGED

RR- RR+ RL+ RL-

BRIDGED

- - + +

SUB

876

9101113141516

5432

181920 1721

1

12

DCX 800.5
Front Panel

17

12. Front HP/LP/FULL Switch: Select the desired crossover
setting. HP/LP/FULL for the speaker output signal of the front
channel.

13. Rear Input INT/EXT Switch: Select the INT position if you want
to use the internal signal path from the front crossover for the rear
input, or the EXT position to use the external rear RCA input.

14. Rear Source INT/EXT Switch: Select the INT position (switch
in) if you want to use the internal signal path from the front crossover
for the rear input, or the EXT position (s witch out) to use the e xternal
rear RCA input.

15. Rear Gain: Use this control to match the output level of the head
unit to the rear channel of the amplifier.

16. Rear Freq. Control: Move this detented control in a clockwise
rotation 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 you
want to use the internal signal path from the rear crossover for the
sub 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 head
unit to the sub channel of the amplifier.

20. Sub Freq. Control: Use this control to adjust the sub high pass
crossover 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 the
speaker output.

18

DCX 600.4, DCX 800.5, DCX 1000.4 END PLATE DIAGRAM

1. Power/Ground

PowerLock

TM

: After you have securely

connected your power and ground wires, plug in the Power/Ground

PowerLock

TM

connector here.

2.

QBASS REMOTE

TM

: Plug in the data cable from the optional

QBASS REMOTE

TM

dash mounted level control here. (The remote

level 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 around
cooling plenums for proper amplifier cooling.

INPUTS

There are two sets of RCA jacks on the front end of your amplifier.
The RCA cables from your source unit go in the set labeled
INPUTS. If your source unit doesn’t have RCA outputs, then add a
set of RCA plugs (available at your dealer) to your front or rear set
of speaker leads (see drawing below). Plug them into the input
jacks, and push in the -12dB input attenuation switch.

t

DCX 600.4, 800.5, 1000.4
Rear Panel

QBASS

REMOTE

QBASS

0 +16

1 2 3 4

19

SOURCE Headunit

eject

VOLUME

123

5

BASS

TREBLE

BALANCE

TRACK

RIGHT

FOWARD

LEFT

4

Trk 1

876

MAR KET

PPI

REVERSE

ING DPT

(+) Positive

(-) Negative

(+) Positive

(-) Negative

LEFT input

RIGHT inpu

DCX 300.4, 600.4, 1000.4 BLOCK DIAGRAM

INPUT ATTENUATIONINPUT ATTENUATION

20

DCX 800.5 BLOCK DIAGRAM

21

ADVANCED INSTRUMENTATION INPUT

The Advanced Instrumentation Input has been incorporated from
the legendary

PrecisionPowerTM2500F1

. This circuit completely
isolates the chassis ground from the audio circuit of the amplifier
and reduces noise radiated into your signal cables by up to 40dB.
This is equivalent to a noise reduction of approximately one hundred
times what the noise level would be without this circuitry. It provides
all the benefits of a true balanced line without the need of any
special cables (see diagram below). This type of input works with
any conventional RCA cables.

QBASS

For extra BOOM from your
system, we’ve developed the

QBASS

TM

bass control circuit.

The

QBASS

TM

control is
located on the end plate
panel, and allows you to add
up to 18dB of boost centered

at 40Hz by rotating the control clockwise.

22

QBASS PLUS

On

DCX 600.4, DCX 800.5

, and

DCX 1000.4

amplifiers, we’ve tak en

bass control to a higher level with

QBASS PLUS

TM

. The two

QBASS

TM

switches (labeled 1 and 2) on the front end of the amplifier
allow you to select one of four frequency centers 30Hz, 36Hz, 44Hz
and 60Hz. On the rear end plate you will find the

QBASS

TM

level

control and plug-in for an optional

QBASS REMOTE

TM

dash
mounted level control. Adjust the level control clockwise for up to
+18dB of boost at your selected frequency.

CAUTION:

QBASS PLUS

TM

should only be used in systems with a
strong subwoofer section. +18dB is a tremendous amount of bass
boost and may damage your speak ers or create e xcessive distortion
if abused.

The optional

QBASS REMOTE

TM

: This boost control can be
mounted in the dash and will supersede the boost control on the
endplate.

The

PrecisionPower DCX

TM

amplifiers no longer need an optional

QPORT

TM

to connect multiple

QBASS PLUS

TM

equipped amplifiers

while using one

QBASS REMOTE

TM

. The new

QBASS PLUS

TM

circuitry in the

DCX

amplifiers is now positioned before the

crossover circuit. In doing this,

PrecisionPower

TM

engineers have
allowed you to daisy chain your RCA output to the next amplifier
input, causing the first amplifier’s

QBASS REMO TE

TM

to become the

master control amplifier. See your authorized

PrecisionPower

TM

dealer for more information!

TC-X CROSSOVER

QBASS

TM

Settings

1 2 Freq.
IN IN 30Hz
IN OUT 36Hz

OUT IN 44Hz
OUT OUT 60Hz

23

Your new

DCX

amplifier has a

TC-X

Crossover (Total Control X-

over

®

) 30Hz-4kHz (see this guide for Crossover Chart).12dB per
octave phase correlated crossover built-in to provide superior
system flexibility without the added expense and installation of an
outboard crossover. The speaker outputs of your amplifier are high
pass, low pass, or all-pass according to the HP/LP/FULL switch on
the front endplate. You would choose low pass (middle position of
switch) to use this amplifier for subwoofers, choose high pass (left
position of switch), or full (right position of switch) to use this
amplifier 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. As
well as being able to independently select HP/LP/FULL, your new

DCX

amplifier allows independent selection of frequencies from

30Hz-4kHz (see Crossover Detent Chart in this guide).

DCX 300.4/600.4/1000.4

Front - 12dB/Octave, Detented High Pass 30Hz-4kHz
Rear - 12dB/Octave, Detented High Pass; HP/LP/FULL

RCA Outputs - 12dB/Octave, Detented High Pass; HP/LP/FULL

QBASS PLUS

TM

- on Rear Channel - up to 18dB @ 30, 36, 44, 60Hz

DCX 800.5

Front - 12dB/Octave, Detented High Pass 30Hz-4kHz
Rear - 12dB/Octave, Detented High Pass; HP/LP/FULL

RCA Outputs - 12dB/Octave, Detented; HP/LP/FULL
Sub-Summed Stereo - 12dB/Octave Detented; 30Hz-4kHz;

HP/LP/FULL

QBASS PLUS

TM

- on Sub Channel - up to 18dB @ 30, 36, 44, 60Hz

24

25

CROSSOVER DETENT CHART

Detent #

Low Pass

Frequency (Hz)

@ -3dB

High Pass

Frequency (Hz)

@ -3dB
1
2
3
4
5
6
7
8
9

10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41

28
28
30
30
30
32
34
36
38
42
46
50
52
54
60
66
76

88
100
116
136
144
168
198
240
286
310
340
380
424
484
576
632
748
932

1076
1428
1700
2436
2830
2980

52
52
52
56
56
60
64
72
76
80
88

92
100
116
132
148
168
192
216
244
284
348
404
468
512
564
624
700
800
932

1036
1144
1300
1504
1812
2196
2840
4116
4540
4728
4728

INPUT COMBINE

Your multi-channel

DCX

amplifier can use both front and rear
outputs from your head unit to maintain the ability to fade front to
rear, or y ou can run a single set of RCAs to the front inputs and push
in the Rear Input INT/EXT switch on the amplifier endplate to route
the front signal to the rear channels as well.

ADJUSTING INPUT GAIN

1. Adjust all amplifier input gain controls to just above minimum

sensitivity (fully counterclockwise).

2. Using the cleanest music source (CD) playing, turn up the head
unit source volume until you can hear distortion. Now turn it down a
bit until you cannot hear the distortion (usually just below full
volume).

3. Increase the amplifier gain (clockwise) until the onset of audible
distortion. Then decrease the gain to the point just before the
distortion starts. This setting minimizes background noise and
prevents overload.

4. Repeat step 3 for any remaining independently controlled
amplifiers (rear and subwoofer gain controls) in the system.

HIGH MASS INTERNAL HEATSINK

The unique heatsink on your

DCX

amplifier has been designed with
fins on the inside of the aluminum extrusion. This allows for the
transfer of heat from the circuitry to the heatsink fins and out through
the vents in the endplates.Be sure you provide ample space around
the amplifier for cooling: at least 2” on all sides.

FORCED AIR THERMAL MANAGEMENT

To manage the additional heat associated with higher output
capability, a thermally controlled fan has been designed into the

DCX 1000.4

. When the heatsink temperature reaches a pre-

determined value, the fan is activated and cool air is drawn in

26

through the lower intake vents on the endplate. This cool air flows
below the circuit board, through the fan and across the internal fins,
cooling the heatsink. The warm air is then forced out through the
upper end-plate exhaust vents.

AP-IV PROTECTION CIRCUIT

Short Circuit Protection engaged: The

DCX

amplifiers will turn off
and try to come back on immediately (the Short RED LED will
illuminate).The amplifier will cycle like this indefinitely with “blips”of
sound each time.If this is the case, check your speakers and wiring
for low impedance and short circuits.

Thermal Protection engaged. The

DCX

amplifiers will turn off and
after a minute or so will come back on (the Thermal RED LED will
illuminate). In this case, ensure that there is nothing blocking the
normal convection airflow of the amplifier. No obstruction should be
within 2” of the amplifier on all sides.

Note: Low battery voltage will cause the amplifier to run
warmer and possibly damage the amplifier.

27

28

TROUBLESHOOTING

NO SOUND Is the LED illuminated?

YES NO

Check Power and Remote
turn-on wire for voltage.
Make sure the ground wire
is secure.

STILL NO SOUND

See your Authorized

PrecisionPower

TM

Dealer or call 1-800-62POWER.
SOUND IN ONE CHANNEL ONLY
Reverse the left and right speakers by unplugging the speaker connector,

turning it over and plugging it back in.

SOUND IS NO

W IN

OPPOSITE CHANNEL SAME CHANNEL

Reverse RCA inputs. Problem is in the speaker or

speaker wire of the silent
channel.

SOUND IS NO

W IN

OPPOSITE CHANNEL SAME CHANNEL

Reverse RCA inputs Problem is in the amplifier.
at head unit. See your local Authorized

PrecisionPower Dealer or
call 1-800-62POWER.

SOUND IS NO

W IN

OPPOSITE CHANNEL SAME CHANNEL

Problem is in the head Problem is in the RCA
unit or before the amplifier. cables.

LIMITED TWO YEAR CONSUMER WARRANTY:

Directed Electronics, Inc. promises to the original purchaser, to replace this
product should it prove to be defective in workmanship or material under normal
use, for a period of two years from the date of purchase b y the dealer as indicated
by the date code marking of the product PROVIDED the product was installed by
an authorized Directed dealer.During this two-year period, there will be no charge
for 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 as
indicated by the date code marking of the product.During this 1-year period there
will be no charge for this replacement PROVIDED the unit is returned to Directed,
shipping pre-paid.This w arranty is non-transf erab le and does not apply to an y unit
that has been modified or used in a manner contrary to its intended purpose, and
does 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 or
unreasonable use, neglect, improper service or other causes not arising out of
defects in materials or construction. ALL WARRANTIES INCLUDING BUT NOT
LIMITED TO EXPRESS WARRANTY, IMPLIED WARRANTY, WARRANTY OF
MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE, AND
WARRANTY OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY ARE
EXPRESSLY EXCLUDED TO THE MAXIMUM EXTENT ALLOWED BY LAW,
AND DIRECTED NEITHER ASSUMES NOR AUTHORIZES ANY PERSON TO
ASSUME FOR IT ANY LIABILITY IN CONNECTION WITH THE SALE OF THE
PRODUCT. DIRECTED HAS ABSOLUTELY NO LIABILITY FOR ANY AND ALL
ACTS OF THIRD PARTIES INCLUDING ITS AUTHORIZED DEALERS OR
INSTALLERS. Unit must be returned to Directed, postage pre-paid, with:
consumer’s name, telephone n umber , and address , authorized dealer’ s name and
address, and product description. IN ORDER FOR THIS WARRANTY TO BE
VALID, YOUR UNIT MUST BE SHIPPED WITH PROOF OF INSTALLATION BY
AN AUTHORIZED DIRECTED DEALER.ALL UNITS RECEIVED BY DIRECTED
FOR WARRANTY REPAIR WITHOUT PROOF OF DIRECTED DEALER
INSTALLATION WILL BE COVERED BY THE LIMITED 1-YEAR PARTS AND
LABOR WARRANTY. Note: This warranty does not cover labor costs for the
removal and reinstallation of the unit. BY PURCHASING THIS PRODUCT, THE
CONSUMER AGREES AND CONSENTS THAT ALL DISPUTES BETWEEN THE
CONSUMER AND Directed SHALL BE RESOLVED IN ACCORDANCE WITH
CALIFORNIA LAWS IN SAN DIEGO COUNTY, CALIFORNIA.

© 2004 Directed Electronics, Inc. All rights reserved. G48235/40/45/55 01-04