Nakamichi NKTA75.2 User manual

NKTA75.2
2 CHANNEL POWER AMPLIFIER
nakamichi.caraudio
nakamichicaraudio.com nakamichi.global

1. User Manual
2. Amplifier
3. Mounting Screw (Φ4x20mm)
4. Fuse(20A)
5. High Level Input Cable
INTRODUCTION
ACCESSORY LIST
N-power Output@4Ω
N-power Output@2Ω
N-power Output@4Ω(bridged)
Max power
T.H.D
Frequency Response
Signal To Noise Ratio
Sensitivity
Fuse Size
Unit Dimensions(LxHxW)
Net Weight
Box Dimensions(LxHxW)
Gross Weight
SPECIFIATIONS
2pcs
1pc
4pcs
1pc
1pc
75Wx2
100Wx2
150Wx1
900W
≤0.1%
20Hz-20kHz
≥90dB
0.15V-8V
20Ax1
240x212x50mm
Approx. 1.7kg
340x267x87mm
Approx. 2.0kg
All specifications subject to change without notice.
Thank you for your purchase of our Nakamichi product and we warmly welcome you
to the Nakamichi family! Do keep your original invoice and purchase receipt in a safe
place in case of future service and warranty claims. You may also contact your
appointed Nakamichi service agent for any future technical support requirements.
1 EN

DIMENSIONS (UNIT:MM)
212
50
240
2 EN

POWER CONNECTION LEADS
BATTERY
3 EN
Notes on the power supply
Connect the +12V power input lead only after all other leads have been connected.
Be sure to connect the ground wire of the unit securely to a meatal part of the car. A
lose connection may cause a malfunction of the amplifier.
REMOTE:
The unit is turned on by applying +12Volts to this terminal. This terminal does not draw
heavy current like the two power terminal so a thinner connecting wire is acceptable.
Standard 18 GAUGE is fine and the standard colour is yellow. If the radio is equipped
with a power antenna control wire, it can drive this terminal. If the power antenna wire
is already in use, you can still splice into it. With this method, the unit will turn on
automatically with the radio.

POWER CONNECTION LEADS
2 - 8 2 - 8
SPEAKER SPEAKER
CONNECTION 1: 2-CHANNEL MODE
4 EN
Use the power supply lead with a fuse attached whose value is the same as original
fuse. Place the fuse in power supply lead as close as possible to the car battery.
During a full power operation, MaxImum current will run through the system. Therefore.
Make sure the that the leads to be connected to the +12V and GND terminals of the
unit respectively must be larger than 8-Gauge(AWG.8).

4 - 8
SPEAKER
POWER CONNECTION LEADS
CONNECTION 2: BRIDGE MODE
5 EN

PANEL CONTROLS AND FEATURES
A B D E F
I
H J K L
CG
A. HIGH LEVEL (speaker level) INPUTS
If your head unit does not have RCA ouputs you can use the speaker outputs for the
audio source for the subwoofer. Use the supplied cable and wire harness and connect
the outputs properly as shown in the connection diagram in this manual.
B. SPEAKER GAIN CONTROL
The gain control will match the amplifiers sensitivity to the source signal voltage.
C. LOW LEVEL RCA INPUT
These RCA input jacks connect with your source unit RCA low level outputs or via
optional adapter with your source unit speaker high level outputs. The use of high
quality twisted pair car audio cables is recommended to reduce the possibility of audio
signal degration.
D. SPEAKER LOW PASS CROSSOVER CONTROL
Amplifier low frequency selector switch.
6 EN

PANEL CONTROLS AND FEATURES
E. SPEAKER LOW PASS CROSSOVER FREQUENCY
Controls low frequency of the amplifier between 40Hz to 150Hz..
F. BASS BOOST
The BASS BOOST feature will increase the sound level in the bass frequencies
G. POWER AND PROTECTION INDICATOR
The protection red LED will light up and flash if there is a fault present in the amplifier.
Please disconnect the amplifier and resolve the foult before reconnecting the
amplifier.
The power indicator green LED will light up when the amplifier is working correctly.
H. GND(-) = GROUND CONNECTION
Connect this coble directly to the metal frame of the vehicle, ensuring that the metal
frame has been strpped of all paint down to the bare metal. Use the shortest distance
possible. It is atways a good idea to replace the vehicle battery groudn terminal or
any other factory ground points.
I. REM(0N/0FF) REMOTE CONTROL
When using HI-INPUT, the omplifier can detect the DC offset from the high level input
signal to outomatically turn the amplifier on or off. When the amplifier turns on, the
REM terminal will output +12V DC to control the other devices to turn on or off. When
using low level inputs, the amplifier REM-IN should be connected to the REM-OUT of
the source unit. The source unit will control the amplifier to automatically turn on or
off.
J. +12V = POWER SUPPLY
Connect this terminal through a fuse or circuit beraker to the positive terminal of the
vehicle battery or the positive terminal of an isolated audio system battery.
K FUSE
Do not use a fuse with a different value and NEVER replace the fuse with a wire or
coin.
L. SPEAKER CONNECTIONS
Connect your speakers and woofers to there terminals, ensuring proper polarity
during connection. Never connect the speaker cables to the chassis ground.
7 EN

INTERFERENCE
All cables can create interference. The power cable and cinch / RCA audio cables are
very prone to interference from other sources, while remote cables are less prone.
Interference is often caused by the generator, ignition, or any other electronic parts or
systems. Most of these problems can be eliminated by correct and careful wiring
during setup. Here are some guidelines to follow.
• Use only a shielded audio cable for the wiring between the low level input of the
amplifier and the RCA or DIN output of the radio.
• Lay the signal, speaker and power cables separately with enough distance from one
another and also from each other car cable. Ir not possible, you can lay the circuit and
ground cable together with the serial cables. Audio and speaker cable should be as
far away from these as possible. The REM cable to the automatic antenna output of
the radio can be laid together with the signal cables.
• Avoid ground loops by laying the ground wiring of all components towards a central
point in a star layout. You can locate fne best point by measuring the voltage directly
at the battery, and comparing the voltage value with the chosen ground point and
the positive terminal of the amplifier. If the measured voltage is only slightly different,
you've found the correct central location. Other wise please look for another point.
You should measure with the ignition point
for earth switched on.
• If there are pickups from external electrical sources into the speaker cables, divide
the core leads and twist them together.
• If there are noises from the car electrics, add an interference suppression choke into
the power wiring.
• If there are humming noises, use thicker ground cables or add further ground cables
to the chassis.
• To reduce contact resistance and bad and loose contacts, please solder the cable
ends or use multi core cable ends, spade terminals or others. Gold Plated spade
terminal are free of corrosion and have the lowest contact resistance.
• Should all these measures not bring about any success, the use of a ground loop
isolator may solve the problem.
8 EN

If you experience operation or performance problems with this product, compare your
installation with the electrical wiring diagram on the previous pages.If problems persist,
read the following troubleshooting tips which may help eliminate the problems.
9 EN
TROUBLESHOOTING
SYMPTOM POSSIBLE CAUSE
Low or no remote turn-on input Check remote turn-on voltage output at amplifier and
correct as needed
Fuse blown
Power wires not connected
Audio input not connected or no
output from source
Speaker not connected to amplifier
properly
Internal crossover not set properly for
speaker
Speaker wires not connected
ACTION TO TAKE
Check power wire integrity and reversed polarity, repair
as needed and replace fuse
Check power wire and ground connections and repair
of replace as needed
Check input connections and signal integrity, repair or
repalce as needed
Short in power wire or incorrect power
connections
Check power and ground connections and repair as
needed
Fuse used is smaller than
recommended
Check speaker wires and repair or replace as needed
Speaker are blown Check system with known working speaker and repair
or replace speaker as needed
Loose or poor audio input
Impedance load to amplifier too low
Check input connections and repair or replace as
needed
Shorted speaker wires Check speaker wire connecrions and repair or replace
as needed
Reset crossovers referring to the multi-cross crossover
configuration section of this manual
Speaker are blown Check system with known working speaker and repair
or replace as needed
Crossover set incorrectly
Replace with proper fuse size
Impedance load to amplifier too low
Crossover configuration secrion of this manual for
detailed instructions
Short in power wire of incorrect Check power and ground connections and repair as
needed
Reset gain referring to the turning section of the manual
for detailed instructions
Thermal protection engages when
amplifier heat sink temperature
exceeds 90℃
Make sure there is proper ventilation for amplifier and
improve ventilation as needed
Check speaker impedance load, if below 2Ω stereo or
4Ω mono rewire speakers to achieve a higher
impedance
Amplifier lecel sensitivity set too high;
exceeding maximum output capability
of amplifier
Check speaker wiring and repair of replace as needed
refer to the installation section of this manual for
detailed instructions
Speaker wired wrong polarity causing
cancellation at low frequencies
Check speaker polarity and repair as needed Reset
crossovers referring to the multi-cross
Check speaker impedance load, if below 2Ω stereo
or 4Ω mono rewire speaker to achieve a higher
impedance
Too much current being drawn
Check speaker impedance load, if below 2Ω stereo
or 4Ω mono rewire speaker to achieve a higher
impedance
NO OUTPUT
DISTORTED
OUTPUT
AUDIO
CYCLES
ON AND
OFF
DISTORTED
OUTPUT (CONT’D)
DISTORTED
OUTPUT
(CONT’D)
POOR BASS
RESPONSE