U.S. Amps MERLIN2 User manual

Owners Manual
and
Installation
Guide
MD
MD
series
2

1
on your selection of a U.S.Amps MD series amplifier.
We take pride in manufacturing our products and you
can expect your new amplifier to give you years of
trouble-free service.
To make your installation as easy and reliable as
possible, please read this manual carefully before
beginning.
If you need more information, your U.S.Amps Dealer
will be glad to help.
Founded in Gainsville, Florida. USA
First “no negative feedback” amplifier
First one-half ohm stable amplifier
“Magnetic Loop Regulation”
First dual-board amplifiers
“Power amplifier strapping”
Plexiglas panel
“Vari-loud” tone filters
First class “D” amplifier at the IASCA Finals
Mirror-polished heat sink
First dual-torroid master/slave MOSFET power supply
XTERMINATOR
“Smart Amp Technology”(SAT)
TRUE DIGITAL full-range stereo performance
Utilize the vacuum tube
Takes a solid step into multi-channel amplifiers
“Class DE” Digital Amplifiers
New lines of products: Merlin2, IS, and AX-Series
New facility in California, USA
XTERMINATOR is BACK!
Introducing “Multi-Link Technology”(MLT)
Whole NEW design of Merlin2 series
1986
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2006
2007
Congratulations
Milestone

2
Congratulations / History(Milestone)
TOC / Genuine Power
Features & Installation
Basic Wiring
• 2-channel / Monoblock
• 4-channel
Bridged Wiring
• 2-channel • 4-channel
• Monoblock(MLT wiring)
Specifications
Troubleshooting
Caution / For Better Listening Experience
Memo
Limited Warranty
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back •••••
CONTENTS
Genuine Power
U.S.Amps is a manufacturer of reliable, high-power quality car
audio amplifiers and accessories.
What is your expectations?
U.S.Amps will meet your needs and provide you with genuine
power and accurately reproduced sound.
No other company offers a wide range of high quality purpose-
designed amplifiers as we do.
Discover the secret of car audio professionals and serious sound
enthusiasts. For 21 years, U.S.Amps has defined the standard of
amplifier quality and power. High performance listeners agree: the
best systems are built on a rock solid foundation of U.S.Amps.
Designed and hand-crafted in our Florida Factory, U.S.Amps are
the finest car amplifiers ever built. All U.S.Amps products are
uniquely designed and carefully engineered to allow for maximum
versatility and dependability.

3
• Use at least 8-gauge wire for power and ground connections
• Use at least 12-gauge wire for speaker connections
• Use at least 16-gauge wire for remote connection
• Mount the amplifier where it can receive the best ventilation
• Use the shortest ground connection to the chassis of the vehicle and make
sure that the paint is removed at the connection point
• Connect the remote input to the remote/antenna output of the head unit
• Mount the fuse holder within 200mm(8”) of the vehicle’s battery. Use a
fuse equal to that specified for your amplifier if a large, single +12V line is
run which feeds more than one amplifier add up all required fuse ratings
and use the total rating for the fuse
• Connect the speaker to the amplifier observing the correct phasing. Make
sure that none of the speaker connections can touch the vehicle chassis
• Connect the RCA inputs to the appropriate signal source using only the
highest quality RCA cables
• Make sure that the RCA and speaker cables do not run parallel to the
+12V wiri ng
INSTALLATION
• High efficiency Class D design(1D/2D/3D)
• Output stages utilize high-current MOSFET devices
• High speed, audio-grade components in all low-level stages
• Active Constant Current Bias Tracking Circuit
• Platinum-plated RCA inputs and connectors
• Wide range of sensitivity accepts signal from any head unit
• 24dB/octave Subsonic Crossover
• 24dB/octave Lowpass Crossover
• True Line Output
• Auto Bridge feature
• Short Circuit Protection
AMPLIFIERS
• High-current MOSFET devices
• MMT-regulated Power Supplies
• 35 nanosecond Switching Diodes
• High capacity Power Transformer
• Multiple Bypass Capacitors on incoming 12V supply
• Time Delay Turn-on with Opto-coupled Muting Circuits
• Power supplies use Pulse-width Modulation
• Thermal and Reverse Polarity Protection
POWER SUPPLY
FEATURES

4
+12V
REM
GND
Impedance: 4~8Ω
GROUND
from REMOTE OUTPUT
of HEAD UNIT
to BATTERY +
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
Both in
“FULL” position
to OUTPUT of
HEAD UNIT
4-channel [MD42/43] Amplifiers
GND
REM
+12V
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
GROUND
+
from REMOTE OUTPUT
of HEAD UNIT
to BATTERY
Impedance: 4~8Ω
[for Monoblock: 1~2Ω]
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
in “FULL” position
to OUTPUT of HEAD UNIT
2-channel [MD21]
and Monoblock [MD1D/2D/3D] Amplifiers
[Basic Wiring]
CONNECTIONS

5
+12V
REM
GND
Impedance: 4~8Ω
GROUND
from REMOTE OUTPUT
of HEAD UNIT
to BATTERY +
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
Both in
“LOW PASS” position
to OUTPUT of
HEAD UNIT
(Y-adapter)
4-channel [MD42/43] Amplifiers
GND
REM
+12V
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
GROUND
+
from REMOTE OUTPUT
of HEAD UNIT
to BATTERY
Minimum
Impedance: 4Ω
P
o
w
e
r
f
u
l
A
m
a
z
i
n
g
l
y
in “LOW PASS” position
to OUTPUT of HEAD UNIT
(Y-adapter)
2-channel [MD21] Amplifier
[Bridged Wiring]
CONNECTIONS

6
GROUND
from REMOTE OUTPUT
of HEAD UNIT
+
to BATTERY
GROUND
from REMOTE OUTPUT
of HEAD UNIT
+
to BATTERY
COMMON
GROUND
Impedance: 4~8Ω
MT
MT
to MLT-in
of “Slave”
to OUTPUT
of HEAD UNIT
for Monoblock [MD1D/2D/3D] Amplifier only
[MLT Wiring] - Master/Slave
CONNECTIONS

7
SPECIFICATIONS
Power Output (RMS)
at full frequency (10Hz~20KHz) (before clipping)
Total Harmonic Distortion S/N Ratio Channel Separation @ 4ΩRMS
Frequency Response Power Band Width (Frequency Response) Crossover Frequency Bass Boost Control @ 45Hz Wired Remote Control Bridged Mono Capable Master Slave Capable Gain Control Damping Factor Dimensions [(W) 2.5/63.5(H) x 8.75/222(D) in/mm] Fuse Rating Protection (thermal, overload, short circuit, dc offset)
Power Voltage Range Input Sensitivity Input Impedance
4Ω 4Ω
4Ωmono
2Ω 1Ω
Input Short
Low Pass
Low Level
High Level
Low
High
Subsonic
High Pass
4Ω
@ 12V
@ 14.4V
100Hz 100Hz
1KHz 1KHz 1KHz 1KHz 1KHz 1KHz
-1dB
24dB 24dB 12dB
4Ω
mV/V
in/mm
A V V
W W W W W W
%
dB dB dB dB
Ω
KΩ
Ω
Hz Hz Hz Hz
KHz
MD21
2 x 75
2 x 100 1 x 200
0.03
105
95 10 10 50
600
7.9/200
30A x 1
40~250
•••
0~12
Yes Yes Yes
12~16V
200/8.0
4
15~40
10~30K
MD42
4 x 75 4 x 90
2 x 180
0.03
100
83 10 10 50
400
12.6/320
30A x 3
40~250
•••
0~12
optional
Yes Yes
12~16V
200/8.0
4
15~40
10~30K
MD43
4 x 100 4 x 150 2 x 300
0.03
100
80 10 10 50
400
12.6/320
30A x 3
40~250
•••
0~12
optional
Yes Yes
12~16V
200/8.0
4
15~40
10~30K
MD1D
1 x 200 1 x 400 1 x 750
1 x 1200
0.09
80
N/A
20~500
22
•••
100
16.5/420
30A x 3
40~250
40~1K
0~12
Yes Yes Yes
12~16V
200/8.0
••• ••• •••
15~40
20~250
MD2D
1 x 550 1 x 300
1 x 1000
1 x 1500
0.09
80
N/A
20~500
22
•••
100
12.6/320
40A x 3
40~250
40~1K
0~12
Yes Yes Yes
12~16V
200/8.0
15~40
20~250
MD3D
1 x 650 1 x 500
1 x 1200 1 x 2000
0.09
80
N/A
20~500
22
•••
100
13.8/350
40A x 3
40~250
•••
0~12
Yes Yes
Yes Yes Yes••• ••• •••
Yes
12~16V
200/8.0
15~40
20~250

8
• Re-adjust the Input Level Control to better suit the input signal.
Weak output
• If the noise is a “whine” whose pitch follows the engine speed, confirm that
the amplifier and any other signal sources (head unit, equalizer, etc) are
properly grounded.
• If the noise is a “clicking” or “popping” noise whose rate follows the engine
speed, this usually means that the vehicle is equipped with resistor spark plugs
and wires, or that the ignition is in need of service.
• Check the routing of the speaker and input wires to make sure they are not
adjacent to wires which interconnect with lights and other accessories.
• If the above steps fail to improve or clear noise interference, the system
souled be checked by a authorized U.S.Amps Dealer.
Noise in the audio
• Confirm that all terminal strip connections are secure and tight.
• Check the “BALANCE” control on the head unit (or other source) to verify that
it is set to its mid point.
• If you are using the low-level RCA input, reverse the input plugs at the
amplifier (switch the R with the L). If the channel which is silent switches to the
other side, the problem is either in the head unit/other source or the connecting
cables.
Only one channel works
• Confirm that all terminal strip connections are secure and tight.
• Check both in-line and built-in fuses.
• Confirm that the audio signal source (car radio, equalizer, etc) is connected
and is supplying output signal. To check if the amplifier is supplying signal,
unplug the RCA cables from the signal source (but leave them plugged into the
amp) and briefly tap the center pin of each of the disconnected RCA plugs
with your finger. This should produce a noise (feedback) in your speakers.
No Output
Before removing your amplifier, refer to the list below and follow
the suggested procedures. Always test the speakers and their wires
first.

9
Information courtesy of the Deafness Research Foundation
Subway, motorcycle, truck traffic, lawn mower90
Garbage truck, chain saw, pneumatic drill100
Rock band concert in front of speakers, thunderclap120
Gunshot blast, jet plane140
Rocket launching pad180
The following noises can be dangerous under constant exposure
Quiet library, soft whispers30
Living room, refrigerator, away from traffic40
Light traffic, normal conversation, quiet office50
Air conditioner at 20 feet, sewing machine60
Vacuum cleaner, hair dryer, noisy restaurant70
Average city traffic, garbage disposal, alarm clock at 2 feet80
ExamplesdB level
Used wisely, you new Merlin will provide a lifetime of fun and enjoyment. Since
hearing damage from loud sound is often undetectable until it is too late, U.S.Amps
and the Electronic Industry Association’s Consumer Electronics Group recommend
you avoid prolonged exposure to excessive loud sound.
We want you listening for a lifetime!
Jump starting your vehicle can cause large voltage spikes within your
automobile’s electrical system. To prevent damage to your stereo system, make
sure the entire system is shut down until full battery charge has been reached
and jumper cables have been removed from the battery.
Caution !

10
Write down key information of your Merlin amplifier(s) as noted
above. Please refer this information when you need assistance
from our technical support or RA service.
You can find important warranty information on the back cover.
Model #:
Serial #:
Purchased Date:
Purchased From:
MEMO

MD
www.usamps.com
Limited Warranty:
U.S.Amps warrants all manufactured electronic products to be free from defects in material and workmanship
for a period not to exceed TWO YEARS from the date of purchase.
IMPORTANT WARRANTY NOTICE: U.S.Amps will only warrant and service products
displaying valid U.S.Amps serial numbers. WARRANTY SERVICE WILL ONLY BE
PERFORMED WHEN THE UNIT IS ACCOMPANIED BY A COPY OF THE ORIGINAL SALES
RECEIPT FROM AN AUTHORIZED DEALER. All product returned to U.S.Amps for service
MUST be accompanied by a Return Authorization Number, issued by U.S.Amps in
advance of shipment. The Return Authorization Number must be clearly and conspicu-
ously displayed on the shipping carton or U.S.Amps will refuse delivery.
For Return Authorization Numbers, first call your U.S.Amps dealer you purchased the products from. The
dealer will help you to obtain Return Authorization Numbers.
This warranty extends only to the original purchaser and is not transferable. Defective equipment must be
returned within the warranty period, freight prepaid, to the U.S.Amps Factory or an Authorized U.S.Amps
Warranty Station.
This warranty covers only detects in materials and workmanship of manufactured electronic
products(amplifiers). Incidents of misuse, abuse, neglect, or unauthorized modification will not be covered
within the terms of this warranty.
U.S.Amps reserves the right to refuse warranty service under such conditions.
U.S.AMPS WILL NOT BE RESPONSIBLE FOR ANY DAMAGES, WHETHER INCIDENTAL OR
CONSEQUENTIAL, RELATED TO THE USE OF THIS OR ANY OTHER PRODUCT BEARING
OR SOLD UNDER THE U.S.AMPS BRAND NAME. USE THIS PRODUCT AT YOUR OWN
RISK. IMPROPER USE OF THIS PRODUCT CAN RESULT IN PROPERTY DAMAGE, BODILY
HARM, AND OR OTHER DAMAGE. U.S.AMPS ASSUMES NO RESPONSIBILITY FOR YOUR
HEALTH OR SAFETY.