model
6550
CONGRATULATIONS
Congratulations for choosing a Directed
Audio power amplifier from Directed
Electronics, the industry leader in high
quality automotive security and audio
equipment since 1990.
enthusiast with years of high-quality
audio reproduction.
Directed Audio power amplifiers come
with a two-year limited warranty if
installed by an authorized Directed
dealer. If not installed by an authorized
dealer, Directed Audio power amplifiers
are covered by a one-year, parts-and-
labor limited warranty.
Directed Audio power amplifiers
continue to set new standards of perfor-
mance, reliability, and affordability in
the mobile electronics industry.
Featuring high-efficiency MOSFET power
supplies, flexible on-board crossovers,
and state of the art audio design,
Directed Audio power amplifiers will
excite and delight the mobile sound
Be sure to retain your original sales
receipt and refer to the warranty section
of this guide for full details about your
coverage.
TABLE OF CONTENTS
Limited Two-Year Consumer Warranty . . . . . . . . . . . . . . . . . . . . . . . . .4
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Installation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Front Panel Connections/Status LED . . . . . . . . . . . . . . . . . . . . . . . . . .8
Rear Panel Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Top Panel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Top Panel Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Speaker Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Crossover Settings and Gain Adjustment . . . . . . . . . . . . . . . . . . . . . . .13
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
3
© 2002 Directed Electronics, Inc
LIMITED TWO-YEAR CONSUMER WARRANTY
Directed Electronics, Inc. promises to the
original purchaser, to replace this product
should it prove to be defective in workman-
ship 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 Directed dealer. During this two -
year period, there will be no charge for this
replacement PROVIDED the unit is returned
to Directed, shipping pre-paid. If the unit is
installed by anyone other than an autho-
rized Directed dealer, the warranty period
will be one year from the date of purchase
by the dealer as indicated by the date code
marking of the product. During this one-year
period there will 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 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 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
DIRECTED DEALER. ALL UNITS RECEIVED
BY DIRECTED FOR WARRANTY REPAIR
WITHOUT PROOF OF DIRECTED DEALER
INSTALLATION WILL BE COVERED BY THE
LIMITED ONE-YEAR PARTS AND LABOR
WARRANTY. Note: This warranty does not
cover labor costs for the removal and rein-
stallation 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.
4
© 2002 Directed Electronics, Inc
FEATURES
„ Dual high-speed MOSFET switching
power supplies and complimentary
bipolar outputs.
„ Two, four, and six channel input
allows full access to source or
processor output functions.
„ Thermal, DC offset, reverse polarity,
„ Summed stereo full-range RCA
outputs with variable two-way
crossover.
and short circuit protection.
„ Top-mounted controls easily
accessed for system tuning.
„ Gold-plated wire terminals and RCA
connectors ensure maximum signal
transfer.
„ Dual continuously variable 12
dB/octave two-way active
crossovers (ch 1-6, RCA output).
„ Rugged one-piece extruded heat
sink finished with injection-molded
mounting feet.
„ Switchable 8 dB bass EQ function
and optional remote subwoofer
level control (ch 5-6).
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.
5
© 2002 Directed Electronics, Inc
INSTALLATION GUIDELINES
1. Please read this owner’s manual
carefully before installing this ampli-
fier.
terminal. Use a fuse or circuit
breaker rated slightly more 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 auto sound
competition organizations have
charts available for this; you can
also find a chart in the MECP study
guide. Minimum wire gauge recom-
mendations for the individual ampli-
fiers are listed on the specification
page. Always 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 if neces-
sary, upgrade it by adding an addi-
tional ground wire that is the same
gauge as the amplifier’s power
wire. Remember, the amplifier can
only deliver its rated output when it
is not current limited by the power
and ground supply wires.
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 amplifier.
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, preferably
scraped body sheet metal. Do not
use factory ground locations, seat
bolts, or brackets that are
spotwelded.
8. This amplifier is designed to drive a
speaker load that measures from 2
to 8 ohms. Keep in mind that heat
is the long-term enemy of automo-
tive electronics and the lower your
7. Always fuse your power connection
within 8 to 10 inches of the battery
6
© 2002 Directed Electronics, Inc
speaker load, the more heat 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, 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. Battery and ground connections to
the vehicle should be made with
crimped ring terminals of the appro-
priate size (surface area is what
counts); soldering the terminals
after crimping is also recom-
mended.
7
© 2002 Directed Electronics, Inc
FRONT PANEL CONNECTIONS/STATUS LED
RCA Input Jacks -
1.
Accepts line level
amplifier shuts down due to short
circuit, DC offset, or overheating
detected by the on-board protection
circuitry.
outputs from head units or signal
processors at voltages between
150mV and 8 volts.
RCA Output Jacks -
Remote Sub Level Control
- Controls
2.
These pass
4.
through RCA jacks can be used to
send a signal to a second amplifier. It
is the summed stereo output of the
one through four channel inputs of
the amplifier.
the gain of channels five and six
from a remote location for ease of
adjustment during listening.
Warning: DO NOT connect a level control knob from other
manufacturers to the Remote Sub Level Control of
any Directed amplifier. Even though the connectors
fit properly, the control knob and connector pin
positions may be different and the amplifier will be
damaged.
Status LED
3.
- Lights GREEN to indi-
cate the amplifier is on and oper-
ating normally, and will be off if the
FIGURE 1—AMPLIFIER CONNECTIONS 6550 FRONT
1
2
3 4
1+2
3+4
5+6
1-4 OUT
R
L
R
L
POWER
REMOTE
8
© 2002 Directed Electronics, Inc
REAR PANEL CONNECTIONS
Speaker Out Terminals
1.
- Connect
the remote turn on lead of the head
unit or signal source. If a (+) 12
volt remote turn on lead is not
available, the Remote Power
Adapter (P/N #55000) can be
used to supply a remote turn on
signal. DO NOT connect this
terminal to constant (+) 12 volt.
the speakers to these terminals.
(Refer to the Speaker Wiring
Diagrams section of this guide.)
Power Fuses -
2.
These fuses protect
the amplifier against internal elec-
trical damage and are meant to
protect the amplifier only. All other
power connections should be fused
at the source.
Ground -
5.
Connect this terminal
directly to the sheet metal chassis
of the vehicle, using the shortest
wire necessary to make this
connection. Always use wire of the
same gauge or larger than the (+)
12 volt power wire. The chassis
connection point should be scraped
free of paint and dirt. Use only
quality crimped and/or soldered
connectors at both ends of this
wire. DO NOT connect this terminal
directly to the vehicle battery
ground terminal or any other
factory ground points.
(+) 12 Volt Power
3.
- Connect this
terminal through a FUSE or CIRCUIT
BREAKER to the positive terminal of
the vehicle battery or the positive
terminal of an isolated audio
system battery.
WARNING: Always protect this power wire by installing a fuse
or circuit breaker of the appropriate size within
12 inches of the battery terminal connection.
Remote Turn On
4.
- This terminal
turns on the amplifier when (+) 12
volt is applied to it. Connect it to
FIGURE 2—AMPLIFIER CONNECTIONS 6550 REAR
1
5
2
3 4
CH 1+2
R
CH 3+4
R
CH 5+6
R
FUSE
30A x 2
BATT
REM
GND
BRIDGE
R
SPEAKER
OUTPUT
L
L
L
L
9
© 2002 Directed Electronics, Inc
TOP PANEL CONTROLS
Input Gain Adjustment
Bass EQ Switch -
Adds 8 db of addi-
tional boost to channels five and six
output when active.
1.
- Controls
4.
5.
amplifier sensitivity and is used to
match the input level of the amplifier
to the output level of the signal
source.
Input Parallel Switch
- Controls the
input signal to the indicated channels.
If the 3+4 switch is ON, channels
three and four will derive their signal
from channels one and two RCA jacks
and no input is needed. If the 3+4
switch is OFF, channels three and four
RCA jacks must have input. If the
5+6 switch is ON, channels five and
six will derive their signals from chan-
nels one through four RCA jacks and
no input is needed. If the 5+6 switch
is OFF, channels five and six RCA
jacks must have input.
Crossover Selection Switch
2.
-
Controls the type of filter for the on-
board active crossovers. FLAT does
not attenuate any frequencies and is
for full-range speaker systems. HPF
attenuates low frequencies and is
used for mid-range speakers and
tweeters. LPF attenuates high
frequencies and is typically used for
subwoofers.
Crossover Frequency Adjustment
Adjusts the crossover point for the
on-board active crossovers.
3.
-
FIGURE 3—AMPLIFIER CONTROLS TOP
BASS EQ
5+6
HPF
4
OFF
ON
LPF
FLAT
FREQ
FREQ
FREQ
3
50Hz50Hz505H00zHz500Hz500Hz
2
1+2
3+4
5+6
LPF
HPF
LPF
HPF
FLAT
FLAT
GAIN
GAIN
GAIN
1
MIN
MAX
MIN
ON
MAX
MIN
MAX
5
OFF
OFF
ON
3+4
INPUT
5+6
INPUT
10
© 2002 Directed Electronics, Inc
TOP PANEL FEATURES
Control Panel Cover
Remove/Install
The gain and filter controls are located
under a control panel cover on top of
the amplifier. The control panel cover
must be removed to gain access to the
gain and filter controls.
Four Allen-head screws hold the control
panel cover to the amplifier top panel,
one at each corner. They can be
removed with the wrench supplied in
the hardware pack.
SPEAKER WIRING DIAGRAMS
Stereo operation (top view)
Six Channel Stereo
Four Channel Stereo with Mono Sub
11
© 2002 Directed Electronics, Inc
Tri amp operation (top view)
Bridged operation (top view)
Three Channel
NOTE:
When wiring the 6550 for three channel operation, connect the left audio signal to both channels one and two RCA jacks
and the right audio signal to both channels three and four RCA jacks using RCA Y adapters.
12
© 2002 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.
„ For full-range and simultaneous stereo/mono bass applications, the crossover
selection switch should be set to FLAT. If the amplifier is driving your subwoofers,
set the switch to LPF, and for mid-bass/midrange output, set to HPF.
„ The crossover frequency control needs to be adjusted to suit your particular system.
For subwoofer applications, try to keep the setting low enough to prevent the
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. For mid-bass/midrange settings, try to keep the setting
low enough to keep your sound stage in front of you, without overdriving the
speaker. It will be to your advantage to spend some extra time with this adjust-
ment, 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 ampli-
fier operation. For full-range and simultaneous stereo/mono bass applications,
start by playing some music you are familiar with. With the gain adjustment 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.
„ For systems using the Remote Sub Level Adjustment, increase the subwoofer gain
on the amplifier by 25% and set the Remote Sub Level knob to the center position
after making all system gain and filter adjustments. This will give the Remote Sub
Level Control a wider range of adjustment to the subwoofer output.
„ The same procedure should be used for adjusting the amplifier when the on-board
crossover is set to LPF or HPF, but you will also have to take into consideration the
effect that gain adjustment has on system frequency response and imaging.
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!
13
© 2002 Directed Electronics, Inc
SPECIFICATIONS
Directed model 6550 Ch 1-4 Ch 5-6
50
watts
75
watts
RMS continuous power per channel, Channels 1-4 driven
into 4 ohms from 20 to 20,000 Hz, with less than 0.08%
total Harmonic Distortion @ 14.4 VDC. Channel 5-6
driven into 4 ohms from 20-250 Hz, with less than
0.08% THD @ 14.4 VDC.
RMS continuous power per channel, Channels 1-4 driven
into 2 ohms from 20 to 20,000 Hz, with less than 0.1%
Total Harmonic Distortion @ 14.4 VDC. Channel 5-6
driven into 2 ohms from 20-250 Hz, with less than 0.1%
THD @ 14.4 VDC.
75
watts
125
watts
RMS continuous power, 3-channel operation, channels 1-
4 bridged into 4 ohms from 20 to 20,000 Hz, with less
than 0.1% Total Harmonic Distortion @ 14.4 VDC.
Channel 5-6 bridged into 4 ohms from 20-250 Hz, with
less than 0.1% THD @ 14.4 VDC.
150x2
watts
250
watts
Dynamic power rating (IHF-202 Standard) at minimum
700 watts
load
Signal-to-Noise Ratio
Frequency Response
Damping Factor @ 4 ohm
Crossovers (ch 1-6)
Greater than 95 dB
20-20,000 Hz 0.5 dB
Greater than 100
Switchable high or low pass
12 dB/octave, continuously
variable 50 to 500 Hz
Bass Equalization (Ch 5-6)
Switchable 8dB,
centered at 40Hz
Input Impedance
20K ohms
Input Sensitivity
Variable from 150 mV to 8 volt
Output Impedance (ch 1-6)
2 to 8 ohms, stereo
4 to 8 ohms, bridged
Supply Voltage
10 to 16 VDC
Fusing and Power
60A
#8
Minimum Cable Requirements (AWG)
(Per amp, trunk mounted)
14
© 2002 Directed Electronics, Inc
The company behind this system is Directed Electronics, Inc.
Since its inception, Directed has had one purpose, to provide customers with the
finest vehicle security, car stereo products, rear seat entertainment, and accessories
available. The recipient of more than 20 patents in the field of advanced electronic
technology, Directed is ISO 9001 registered.
Directed Electronics, Inc.
Vista, California 92083
Directed® is committed to delivering world-class quality
products and services that excite and delight our customers.
Directed is a proud member of
Quality Directed products are sold and serviced throughout North America and around the world
Call 800 274 0200 for more information about our products and services
© 2002 Directed Electronics, Inc. - All rights reserved - G45066 02/02
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