OWNER’S MANUAL
Model 250d
TABLE OF CONTENTS
Installation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 2
Amplifier Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 4
Amplifier Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 5
Speaker Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
Crossover Setting and Gain Adjustment . . . . . . . . . . . . . . . .Page 7
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 8
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 9
WARNING
High-powered car audio
systems may produce
sound pressure levels that exceed the
threshold at which hearing loss may
result.
They may also impair a driver’s ability to
hear traffic sounds or emergency vehi-
cles. Use common sense and practice
safe listening habits when listening to or
adjusting your audio system.
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© 1999 Directed Electronics, Inc
INSTALLATION GUIDELINES
1. Please read the owner’s manual
carefully before you install the ampli-
fier.
2. Disconnect the battery ground
terminal prior to making any elec-
trical connections.
3. Check for any hazards or obstruc-
tions such as gas tanks, fuel or
brake lines, and wiring harnesses
before mounting the amplifiers.
4. Pick a mounting location that will
provide adequate access and venti-
lation and protect the amplifier
from heat, moisture, and dirt.
5. Avoid sharp metal areas when
routing cables to the amplifier, and
run RCA cables away from the
power cables and other potentially
noisy car harnesses.
6. The amplifier should be grounded
with a short, heavy gauge wire
connected directly to the car at a
bare metal surface. Make sure that
the metal area is part of the car
chassis or frame, not a separate
part with poor electrical connection
to the chassis.
7. Always fuse your power connection
at the battery within 8-10 inches of
the battery terminal. Use a fuse or
circuit breaker rated at about 5-10
more amps than the on board
fuse(s) of the amplifier(s). The
gauge of power wire used should
take into account the total current
draw of the system, and the length
of wire used. IASCA and other
autosound competition organiza-
tions have charts available for this;
you can also find a chart in the
MECP study guide. Minimum wire
gauge recommendations for the
individual amplifiers are listed on
the specification page. It is a good
idea to use the same gauge wire
for the amplifier ground that you
use for the power wire. Be sure to
examine the battery ground cable
of the vehicle and upgrade it to a
gauge of wire that can accommo-
date the extra load created by your
amplifier installation. Remember,
the amplifier can only deliver its
rated output when it is not current
limited by the power and ground
supply wires.
8. This amplifier is designed to drive a
speaker load that measures from 2-
4 ohms. Keep in mind that heat is
the long-term enemy of automotive
electronics and that the lower your
speaker load, the more heat
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© 1999 Directed Electronics, Inc
INSTALLATION GUIDELINES (continued)
is generated. For low impedance
speaker applications or restricted
ventilation installations, an external
cooling fan may be advisable.
10. Due to the high-frequency MOSFET
switching power supply used in all
Directed Audio amplifiers, 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.
9. Your connections to the amplifier’s
speaker and power terminals
should be made with crimped spade
lugs, and the battery and ground
connections to the vehicle should be
made with crimped ring terminals
of the appropriate size (surface
area is what counts); soldering the
terminals after crimping is also
recommended.
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© 1999 Directed Electronics, Inc
AMPLIFIER CONNECTIONS
Refer to Figure 1 for details.
not connect this terminal to a
constant source of +12V.
1. GROUND TERMINAL - connect this
terminal to the car chassis with a
short heavy gauge wire, DO NOT
CONNECT TO THE NEGATIVE
TERMINAL OF THE CAR BATTERY or
to factory chassis ground points
already occupied by factory wires!
If you are grounding multiple ampli-
fiers, you may use a high-current
distribution block with proper gauge
cables, or use individual grounds for
each amp attached to the vehicle at
separate but close ground points.
2. REMOTE TERMINAL - connect this
terminal to the amplifier remote
output from your head unit or signal
source, if it provides one. You may
also use the power antenna output
wire from decks that do not have
separate amp remote outputs. This
input requires a switched +12V
signal to activate the amplifier. Do
3. +12V POWER TERMINAL - connect
this terminal to the positive terminal
of the car or separate audio system
battery. Refer to the installation
guidelines and specs page for proper
gauge of wire. YOU MUST PROTECT
THIS WIRE WITH A FUSE or circuit
breaker located close to the battery.
4. POWER FUSE - protects the ampli-
fier against electrical damage. DO
NOT REPLACE THE FUSE OR FUSES
WITH LARGER AMPERAGE FUSES !
If the fuse(s) blows, check your
system for wiring problems or see
your dealer.
5. SUBWOOFER OUTPUT TERMINALS
- connect the speakers to these
terminals. Refer to the speaker
wiring diagrams (pg. 6) for
different wiring options.
FIGURE1—AMPLIFIER CONNECTIONS
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© 1999 Directed Electronics, Inc
AMPLIFIER CONTROLS
Refer to Figure 2 for details.
1. RCA OUTPUT JACKS - use these
jacks to route the input signal to
another amplifier.
5. CROSSOVER FREQUENCY - controls
the frequency range of the ampli-
fier.
2. RCA INPUT JACKS - accepts line-
level outputs from head units or
signal sources at voltages from
200 mV to 8 volts.
6. BASS EQ - This switch activates an
8 dB bass boost circuit. Use as
necessary for low frequency
enhancement.
3. GAIN ADJUSTMENT - controls the
gain (input sensitivity) of the
amplifier.
4. PHASE INVERT SWITCH - controls
the output phase of the amplifier.
The signal is inverted with the
switch set to 180.
7. LED INDICATOR - the green Power
LED lights to indicate normal opera-
tion. The green LED will shut off to
indicate amp shutdown due to
thermal, short circuit, DC offset, or
over-current conditions detected by
on-board protection circuits.
FIGURE 2—AMPLIFIER CONTROLS
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© 1999 Directed Electronics, Inc
SPEAKER WIRING DIAGRAMS
Single subwoofer connection
Speaker nominal impedance must be at
least 2 ohm. Amplifier parallels the
speaker terminals internally.
Two subwoofer connection
Parallel speaker nominal impedance must
be at least 2 ohm. Amplifier parallels the
speaker terminals internally.
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© 1999 Directed Electronics, Inc
CROSSOVER SETTINGS AND GAIN ADJUSTMENT
Your Directed Audio power amplifier needs to be adjusted carefully to achieve
maximum performance. These are some guidelines to follow when fine-tuning the
amplifier.
• Because the 250d is only suited for subwoofer applications, the low-pass crossover is
active at all times. The crossover point is adjustable to allow more precise system oper-
ation.
• 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 advan-
tage 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. With the gain adjust-
ment on the amplifier in the middle of its rotation, bring up the volume on your head
unit to the 3/4 volume setting or until you start to hear distortion or clipping. If you
hear distortion before you reach the 3/4 volume setting of your head unit, reduce the
gain setting on the amplifier and start to raise the head unit volume again. When you
can listen to the music at or slightly above 3/4 on your head unit without audible
distortion, slowly raise the gain of the amplifier until distortion is heard, then back off
the gain until the distortion is not audible. This setting will allow you to reach full
output with all but the quietest of source material, while avoiding excessive noise in the
system.
• You should take into consideration the effect that gain adjustment has on system
frequency response and staging. Again, plan on spending some time with music that
you know getting the gain and crossover settings the way you like. Test discs and
analyzers may help with this process, but in the end it's your ears that count - listen to
the music !
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© 1999 Directed Electronics, Inc
SPECIFICATIONS
model 250d
RMS continuous power driven into 4 ohms
from 20 to 250 Hz with less than 0.4% Total
Harmonic Distortion @ 14.4 VDC
125 watts
250 watts
300 watts
RMS continuous power driven into 2 ohms
from 20 to 250Hz with less than 0.6% Total
Harmonic Distortion @ 14.4 VDC
Dynamic power rating (IHF-202 Standard) at
minimum load
Signal-to-Noise Ratio
Frequency Response
Greater than 80 dB
20-250 Hz +0, -1 dB
Damping Factor
Crossover
50 (typical)
Low-pass 12 dB/octave
variable from 30 to 250 Hz
Bass Equalization
Input Impedance
+8 dB, centered at 40Hz
20K ohms
Input Sensitivity
Output Impedance
Supply Voltage
Variable from 150 mV to 8 volt
2 to 4 ohms
10 to 16 VDC
Fusing and Power
Cable Requirements (AWG)
(Per amp, trunk mounted)
20A
#12
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© 1999 Directed Electronics, Inc
LIMITED TWO YEAR CONSUMER WARRANTY
®
Directed Electronics, Inc. (DEI ) 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 by the dealer as indicated by the
date code marking of the product
PROVIDED the product was installed by an
authorized DEI dealer. During this two year
period, there will be no charge for this
replacement PROVIDED the unit is returned
to DEI, shipping pre-paid. If the unit is
installed by anyone other than an autho-
rized DEI dealer, the warranty period will be
1 year from 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 DEI, ship-
ping pre-paid. This warranty is non-transfer-
able and does not apply to any 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 PARTIC-
ULAR PURPOSE, AND WARRANTY OF
NON-INFRINGEMENT OF INTELLECTUAL
PROPERTY ARE EXPRESSLY EXCLUDED TO
THE MAXIMUM EXTENT ALLOWED BY
LAW, AND DEI NEITHER ASSUMES NOR
AUTHORIZES ANY PERSON TO ASSUME
FOR IT ANY LIABILITY IN CONNECTION
WITH THE SALE OF THE PRODUCT. DEI
HAS ABSOLUTELY NO LIABILITY FOR ANY
AND ALL ACTS OF THIRD PARTIES
INCLUDING ITS AUTHORIZED DEALERS
OR INSTALLERS. Unit must be returned to
DEI, postage pre-paid, with: consumer’s
name, telephone number, 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 DEI
DEALER. ALL UNITS RECEIVED BY DEI FOR
WARRANTY REPAIR WITHOUT PROOF OF
DEI 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 DEI SHALL BE RESOLVED IN ACCOR-
DANCE WITH CALIFORNIA LAWS IN SAN-
DIEGO COUNTY, CALIFORNIA.
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© 1999 Directed Electronics, Inc
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SIGNAL PROCESSORS
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SINGLE AND DUAL VOICE COIL SUBWOOFERS
COAXIAL SPEAKERS
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COMPONENT SPEAKER SYSTEMS
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COMPONENT NEODYMIUM SPEAKER SYSTEMS
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SINGLE AND DUAL VOICE COIL DIE-CAST SUBWOOFERS
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HIGH PERFORMANCE POWER CABLES
PREMIUM SPEAKER/AUDIO CABLES AND ADAPTERS
POWER CAPACITORS
GOLD-PLATED POWER DISTRIBUTION AND FUSING BLOCKS
GOLD-PLATED POWER AND SPEAKER TERMINALS
Always use a
DEI is a proud member of
G45012 9/99
© 1999 Directed Electronics, Inc • Vista, CA 92083 • All Rights Reserved
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