MDS MDS GP800 Service manual

MOSFET POWER AMPLIFIERS
Installation Instructions / Owner's Manual
MDS GP800
MDS - Multi Dynamic Systems of Sweden AB
Midsommarv. 8-10
126 35 Hägersten
[phone]
www.mds.se

1

INTRODUCTION
Congratulations on your purchase of a MDS state-of-the-art power amplifier. Your
selection of a MDS product indicates a true appreciation of fine musical reproduction.
Whether adding to an existing system or including your MDS amplifier in a new system,
you are certain to notice immediate performance benefits.
KEEP YOUR SALES RECEIPT
Take this time to attach your sales receipt to the manual and put in a safe place. In case
of any unforeseen reason this product may need warranty service, your receipt will be
necessary to establish purchase date.
RECOMMENDATION
A power amplifier’s performance is only as good as its installation. Proper installation will
maximize the system’s overall performance. It is recommended that you have our
product installed by an authorized MDS retailer. However, if you decide to install it
yourself, please carefully read through this manual and take your time to do a quality
installation.
WARNING!
Exposure to high power sound system can cause hearing loss or damage.
Listening to your system at loud levels while driving, will impair your ability to
hear traffic sounds and emergency vehicles. Use common sense when listening
to your system.
WARNING!
Exposure to high power sound system can cause hearing loss or damage.
Listening to your system at loud levels while driving, will impair your ability to
hear traffic sounds and emergency vehicles. Use common sense when listening
to your system.
IMPORTANT! Before making any connections, disconnect the car’s battery until
the installation is completed to avoid possible damage to the electrical system.
Serial # Model #
2

SAFETY PRECAUTIONS
Fuse amplifiers power wire at the battery.
Be sure to fuse the power wire within 12” of the car's battery. This will protect the car's
battery in case of a short circuit between the power amplifier and battery. THIS IS A
MUST, the amplifier's built-in fuse will only protect the power amplifier not the car's
battery!
Use high grade wire connectors.
To ensure maximum power transfer and secure safe connections, it is recommended to
use high grade barrier spades (for connection at amplifier) and terminal rings (for
connection at battery).
Do not run any wires underneath vehicle.
Exposed wires have a chance of being cut or damaged. It is best to run all wires through
the vehicle under the carpet and/or side panels. This lends to a cleaner installation and
less risk of damage.
Use caution when mounting amplifier.
Remember there are many electrical wires, gas lines, vacuum lines, brake lines as well
as a gas tank in the automobile. Make sure you know where they are when mounting the
amplifier to avoid puncturing lines, shorting wires or drilling holes in the gas tank.
Run signal wires away from electrical wires.
To avoid possibility of induced noise from the car's electrical system (i.e. popping noises
or engine noise), run wires away from the car's electrical wiring.
Make all ground wires as short as possible and at the same point.
In order to reduce the chance of ground loops (i.e. engine noise), make the grounding
wire as short as possible to reduce the wire's resistance. Also, when using multiple
components, make sure all units are grounded at the same point.
Avoid sharp edges when running the wires.
To avoid the possibility of power, signal or speaker shorts, be careful not to allow the
amplifiers wires to come in contact with sharp edges. Use a grommet to protect the wire
when running through the fire wall .
3

FEATURES AND BENEFITS
DC Offset Protection
This circuit protects the output of the amplifier against DC voltage. If for some reason DC
voltage is detected at the output stage, the amplifier will shut down protecting the
speakers from direct current.
Short Circuit Protection
The circuit protects the amplifier from damage due to a short found in the speakers or
wiring. If one of the speakers or its wiring comes in contact with ground, the amplifier will
shut down. To resume normal operation, correct the problem and turn the head unit off,
then back on. The amplifier will reset and play again.
Thermal Protection
To protect the amplifier circuitry against damage caused by prolonged exposure to high
temperatures, a thermal protection circuit is activated if the amplifier reaches excessively
high operating temperature. Once the thermal circuit is activated, the amplifier will shut
down to cool off. The amplifier will automatically turn back on once it cools down to a safe
operating temperature.
Power & Protection Indicator
The power L.E.D. Illuminates when the amplifier is on and receiving power. The protect
LED Illuminates when the amplifier has gone into the protection mode (Please refer to our
trouble shooting section).
Built-in Crossover
The MDS amplifier include a built-in combination variable high and low pass crossover.
The low pass filter works together with the (subsonic) high pass filter to achieve band
pass filtering. This concentrates the amplifier’s output power to your subwoofer optimum
frequency range .
Bass Boost
For added low frequency performance the amplifiers are equipped with a variable
0~12 dB bass boost @ 45Hz.
Power Fusing
This protects the amplifier against short circuits and excessive current.
Adjustable Input Sensitivity
Allows you to fine-tune the level matching between your source and the power amplifier.
4

Remote Turn-on
Automatically turns amplifier on when connected to the head unit's remote output. The
amplifier will turn on and off with the head unit to save current consumption. This control
also operates the reset circuit for the amplifier's protection. It must be connected with the
head unit in order to reset protection circuits.
Stable To 2 Ohm
Amplifier output impedance stable down to a 2 ohm load.
5

MOUNTING LOCATION
Before you start the installation, it will be necessary to find a mounting location for the
amplifier. Find a location in which the amplifier will receive adequate ventilation in order
to dissipate the heat it develops during operation. Two popular mounting locations are in
the trunk or under the seat.
Select the location in which you wish to mount the amplifier. Use caution when mounting
amplifier, there are many wires, gas lines, vacuum lines, brake lines as well as a gas tank
in the automobile. Make sure you know where they are when mounting the amplifier to
avoid puncturing lines, shorting wires or drilling holes in the gas tank. Once you are
ready, use a pencil to mark the mounting holes in the bottom panel. After you have
marked the locations of the holes move amplifier out of the way and drill small starter
holes to make the tapping screws easier to install. Use provided screws to tighten down
the amplifier.
6
BASS BOOST REMOTE
12dB
OdB
HIGH PASS LOW PASS
50Hz 400Hz
10Hz 40Hz
LEVEL
0.2V
5V
POWER
INPUT
L
R
PROTECT

SPEAKER FUSE POWER
+12V REM GND
20A 20A 20A 20A
CAR BATTERY
+12V
CAR BATTERY
+12V
--
++
POWER CONNECTIONS
IN-LINE POWER FUSE
MOUNTED WITHIN 12"
FROM BATTERY RECOMMENDED
IN-LINE POWER FUSE
MOUNTED WITHIN 12"
FROM BATTERY RECOMMENDED
(NOT PROVIDED)(NOT PROVIDED)
94.794.7
RADIO'S REMOTE
TURN-ON OUTPUT
RADIO'S REMOTE
TURN-ON OUTPUT
Connect the amplifier to the car's battery.
At times, the amplifier will need to draw large levels of current that cannot be provided by
any circuit in the car's fuse box. We recommend using a 4 to 8 gauge power wire for your
connections depending on the length of the wire. Strip one end of the wire and connect
to the terminal on the amplifier marked “+12V”. Loosen screw terminal and insert bare
wire and tighten. Use caution to make sure no stray wire stands come in contact with
surrounding terminals causing short circuits. Run the wire directly to the positive terminal
of the car's battery. Make sure to use an in-line fuse within 12” of the car's battery to
protect the electrical system and amplifier against short circuits and/or power surges.
Connect the ground terminal of the amplifier to the car's chassis.
For the ground connection, use an 4 to 8 gauge wire (black) to connect to the terminal
marked GND and then connect it to the car's chassis. Try to keep the length of the cable
as short as possible, preferably less than 6". Also make sure that the point on the car
where the connection is to be made is free of paint and dirt.
Connect the remote terminal of the amplifier to a switchable +12V source.
This connection allows the amplifier to be turned on and off with the power control of the
radio. If the radio has a REMOTE output terminal, connect it to the amplifier's terminal
marked REMOTE (using a 16 gauge wire or heavier). Now when the radio is turned on,
the amplifier will automatically turn on. This connection can also be made to the radio’s
PowerAntennawire.
IMPORTANT! Before making any connections, disconnect the car’s battery until the
installation is completed to avoid possible damage to the electrical system.
7

BASS BOOST REMOTE
12dB
OdB
HIGH PASS LOW PASS
50Hz 400Hz
10Hz 40Hz
LEVEL
0.2V
5V
POWER
INPUT
L
R
PROTECT
SIGNAL CONNECTIONS
8
SIGNAL CONNECTIONS
Connect the RCA output of the head unit (AM/FM cassette player, CD, or DAT) to
the RCA input terminals of the amplifier.
To make these connections, we recommend high quality RCA cables, which are
available at your local car audio retailer. Run signal wires away from electrical wires to
avoid possibility of induced noise from the car's electrical system (i.e. popping noises or
engine noise). Please note that when making these connections the signal inputs
correspond with the speaker outputs.
LLRR

Make the speaker connections using speaker wire that is at least 16 gauge or heavier.
As with any audio component, proper phasing of the amplifier and speakers is essential
for strong bass response. When connecting, make sure that positive (+) from the
amplifier is connected to the positive (+) of the speaker, and the same for negative (-).
SPEAKER CONNECTIONS
9
SINGLE 4 OHM SPEAKER
SPEAKER FUSE POWER
+12V REM GND
20A 20A 20A 20A
4 Ohm Speaker4 Ohm Speaker
++
--
CAUTION! The amplifier must see a 2 Ohm load or higher. Any lower than 2 Ohms will
cause the amplifier to overheat and possibly cause permanent damage to the amplifier!
TWO 4 OHM SPEAKERS IN PARALLEL (2 Ohm)
SPEAKER FUSE POWER
+12V REM GND
20A 20A 20A 20A
4 Ohm Speaker4 Ohm Speaker
++
--
4 Ohm Speaker4 Ohm Speaker
++
--

BASS BOOST REMOTE
12dB
OdB
HIGH PASS LOW PASS
50Hz 400Hz
10Hz 40Hz
LEVEL
0.2V
5V
POWER
INPUT
L
R
PROTECT
REMOTE BASS CONTROL MODULE
Before connecting the remote, it will be necessary to find a mounting location that will be
easy to access for adjustment. Once you select your mounting location, you will need to
run the control wire from the remote to the amplifier. To avoid possibility of induced noise
from the car's electrical system (i.e. popping noises or engine noise), run the cable from
the remote to the amplifier away from the car's electrical wiring.
Please note: Once the remote is plugged in, it overrides the bass boost on the amplifier
and becomes the primary bass adjustment.
10

The MDS amplifier features a built-in combination variable high and low pass crossover.
The low pass filter works together with the (subsonic) high pass filter to achieve band
pass filtering. This concentrates the amplifier’s output power to your woofer’s optimum
frequency range for maximum performance.
Before making adjustments, lower the (subsonic) “High Pass” control to 10Hz by rotating
in the full counter clockwise position. Next select the desired Low Pass frequency. The
crossover point should be determined by the speaker’s recommended operating range.
Once you have set the “Low Pass frequency, adjust the “High Pass” control clockwise
while listening to the system until you hear the Bass output start getting thinner (lower) in
sound then stop. This will filter out the subsonic frequencies below the speaker’s normal
operating range for improved output.
Fine tune the bass by adjusting the Bass Boost Control to deliver up to 12dB of boost at
45Hz.
You can add up to 12dB bass boost by
increasing the Bass Boost control.
Filter out unwanted subsonic frequencies
below the woofer’s audible range by
adjusting the high pass filter.
Select the Low Pass crossover point
for your woofers.
ADJUSTING THE X-OVER AND BASS
Fine tune the amplifier's input sensitivity.
The gain sensitivity control for the MDS
amplifier is located on the side panel. This gain control
has been included to allow adjustment to properly
match the output of the radio. This is one of the most
misunderstood adjustments. By rotating the control in
the clockwise direction, the amplifier‘s input will
become more sensitive and the music will play louder. This
is not a volume control and you will not get more power out of the amplifier in the
maximum position! It may seem to deliver more output, but actually the system is only
playing louder faster as you turn the volume control on the radio. Ideally, to properly level
match the system the goal is to achieve maximum output from the amplifier without
distortion at about 3/4 of the volume control.
To determine if the amplifier’s gain is set properly, turn the system on and slowly increase
the volume control. You should be able to use about 3/4 volume before the system gets
loud but not distorting. It is very important when making these adjustments that you do
not over drive the speakers (at point of distortion) this will cause permanent damage to
the speakers. If you are unable to achieve 3/4 volume before distortion you will need to
adjust gain control (in this case you would reduce the gain). The gain controls should be
adjusted very slowly. It may help to have another person to assist you by adjusting the
gain controls while you listen for distortion.
FINE TUNE THE SYSTEM
11
MAX
MIN
LEVEL
0.2V
5V
BASS BOOST
12dB
OdB
HIGH PASS LOW PASS
50Hz 400Hz10Hz 40Hz

TROUBLE SHOOTING THE SYSTEM
We have put together this trouble-shooting guide if you experience problems after
installing the amplifier. Please keep in mind that the majority of problems incurred are
caused by improper installation and not the equipment itself. In addition, there are many
components in the system that could cause various signal problems such as inducted
electrical noise and engine noise.
Before you can properly address the problem, you must first find the component that is
causing the problem. This will take patience and a process of elimination.
LOOK FOR.... SOLUTION
No Output
Blown fuse Replace
Bad RCA Cable(s) Replace
+12V at power terminal Check connection
+12V at remote terminal Check connection
Grounding point clean and tight Check for ground w/meter
Head Unit's fader not in center position Set to center position
Low Output
Check level adjustments Re-adjust
Bad RCA cable(s) Replace
Improper level matching Re-adjust
Engine Noise
Grounding points are clean and tight Check for ground w/meter
Ground all components at same point Ground at same point
Try different grounding point Change for better ground
Bad RCA cable(s) Replace
Use High Quality shielded RCA cables Rejects inducted noise
Low Vehicle charging system and/or battery Fix and/or replace
Protection L.E.D. Illuminated
Speaker short Check speakers connection
for short circuit
Speaker grounding out Make sure speaker wires
do not touch chassis ground
Impedance too low Check speaker impedance
(Min 2 ohm )
Overheating Check mounting location
for Adequate air Circulation
Speaker impedance too low
12

13
SPECIFICATIONS
MDS GP800
Output Power @ 14.4 VDC :
4 ohm ........................................................................................................................400W
2 ohm ........................................................................................................................800W
Frequency Response ................................................................................................10Hz-400Hz
S/N Ratio (A-weight.............................................................................................................>85dB
THD with 20k filter ............................................................................................................... .50%
Low Input Level.............................................................................................................200mV-5V
Battery Voltage Range ....................................................................................10.5VDC-15.5VDC
Crossover High Pass ..................................................................................................10Hz-50Hz
Crossover Low Pass..................................................................................................40Hz-400Hz
Crossover Slope .............................................................................................................12dB/Oct
Bass EQ ...............................................................................................................0-12dB @ 45Hz
Remote Bass control................................................................................................................Yes
Fuse...................................................................................................................................4 x 20A
Due to continuing product improvement, specifications subject to change without notice.

14

MDS - Multi Dynamic Systems of Sweden AB
Midsommarv. 8-10
126 35 Hägersten
[phone]
www.mds.se
Manual By
www.extremeconcepts.com
MDS GP800 REV 4.20.06