Nakamichi NGO-A4250 User Manual
4 CHANNEL POWER AMPLIFIER
Website: nakamichicaraudio.com | nakamichi.global | nakamichi.caraudio
Introduction
Thank you for your purchase of our Nakamichi product. We warmly welcome you to the Nakamichi family! Please keep your original invoice and purchase receipt in a safe place for future service and warranty claims. You may also contact your appointed Nakamichi service agent for any future technical support requirements.
Accessory List
- User Manual: 1 pc
- Amplifier: 1 pc
- Mounting Screw (M4x16mm): 4 pcs
- 16P Cable: 1 pc
Specifications
| Feature | Specification |
|---|---|
| Max power | 50Wx4 |
| T.H.D | <0.1% |
| Frequency Response | 20Hz-20KHz |
| Signal To Noise Ratio | ≥88dB |
| Sensitivity | 0.2~6 |
| Unit Dimensions (LxHxW) | 77x107x43mm |
| Net Weight | Approx. 0.8kg |
All specifications subject to change without notice.
Dimensions (Unit: MM)
The amplifier has dimensions of 77mm (width) x 107mm (length) x 43mm (height).
Panel Controls and Features
The front panel features:
- A/B: Left/Right RCA output
- C: Rear 2-channel volume adjustment
- D: Front 2-channel volume adjustment
- E: Connection to Android Navigation Host
- F: Car connection with original car harness
Power Connection Leads
The amplifier connects to an Android Receiver via a power and audio cable. The unit also has connections labeled 'TO HEAD UNIT' and 'TO AUTOMOTIVE'.
A. Power Supply Wiring Details
| No. | Color | Full Name |
|---|---|---|
| 1 | Yellow | +12V Power Cord |
| 2 | Black | Ground Wire |
| 3 | Orange | Small Light Detection Line |
| 4 | Red | Ignition Switch Wire |
| 5 | Brown | Steering Wheel Control Line 2 |
| 6 | Pink | Reversing Detection Line |
| 7 | Blue | Automatic Antenna Power Supply |
| 8 | Orange/Black | Steering Wheel Control Line 1 |
| 9 | Green/black | Rear Left Speaker - |
| 10 | Gray/black | Front Right Speaker - |
| 11 | Green | Rear Left Speaker + |
| 12 | Gray | Front Right Speaker + |
| 13 | Purple | Rear Right Speaker + |
| 14 | White/black | Front Left Speaker - |
| 15 | Purple/black | Rear Right Speaker - |
| 16 | White | Front Left Speaker + |
B. Audio Input
C. Audio Output
Interference
All cables can create interference. Power and RCA audio cables are more prone to interference than remote cables. Interference is often caused by the generator, ignition, or 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 wiring between the low-level input of the amplifier and the RCA or DIN output of the radio.
- Lay signal, speaker, and power cables separately with sufficient distance from each other and from other car cables. If not possible, you can lay the circuit and ground cable together with the serial cables. Audio and speaker cables should be as far away 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 the 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. Otherwise, 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/loose contacts, please solder the cable ends or use multi-core cable ends, spade terminals, or others. Gold-plated spade terminals are free of corrosion and have the lowest contact resistance.
- If all these measures do not bring about any success, the use of a ground loop isolator may solve the problem.
Troubleshooting
If you experience operation or performance problems, compare your installation with the electrical wiring diagram. If problems persist, read the following troubleshooting tips:
| Symptom | Possible Cause | Action to Take |
|---|---|---|
| NO OUTPUT | Low or no remote turn-on input | Check remote turn-on voltage output at amplifier and correct as needed. |
| Fuse blown | Check power wire integrity and reversed polarity, repair as needed and replace fuse. | |
| Power wires not connected | Check power wire and ground connections and repair or replace as needed. | |
| AUDIO CYCLES ON AND OFF | Audio input not connected or no output from source | Check input connections and signal integrity, repair or replace as needed. |
| Speaker wires not connected | 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. | |
| DISTORTED OUTPUT | Thermal protection engages when amplifier heat sink temperature exceeds 90°C | Ensure there is proper ventilation for amplifier and improve ventilation as needed. |
| Loose or poor audio input | Check input connections and repair or replace as needed. | |
| DISTORTED OUTPUT (CONT'D) | Amplifier level sensitivity set too high, exceeding maximum output capability of amplifier | Reset gain referring to the tuning section of the manual for detailed instructions. |
| Impedance load to amplifier too low | Check speaker impedance load; if below 2Ω stereo or 4Ω mono, rewire speakers to achieve a higher impedance. | |
| POOR BASS RESPONSE | Shorted speaker wires | Check speaker wire connections and repair or replace as needed. |
| Speaker not connected to amplifier properly | Check speaker wiring and repair or replace as needed; refer to the installation section of this manual for detailed instructions. | |
| DISTORTED OUTPUT (CONT'D) | Internal crossover not set properly for speaker | 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. | |
| CONTINUOUS OUTPUT | Speaker wired wrong polarity causing cancellation at low frequencies | Check speaker polarity and repair as needed. Reset crossovers referring to the multi-cross crossover configuration section of this manual for detailed instructions. |
| Impedance load to amplifier too low | Check speaker impedance load; if below 2Ω stereo or 4Ω mono, rewire speakers to achieve a higher impedance. | |
| LOW BASS RESPONSE | Short in power wire or incorrect power connections | Check power and ground connections and repair as needed. |
| Fuse used is smaller than recommended | Replace with proper fuse size. | |
| Too much current being drawn | Check speaker impedance load; if below 2Ω stereo or 4Ω mono, rewire speakers to achieve a higher impedance. | |
| LOW BASS RESPONSE (CONT'D) | Short in power wire or incorrect power connections | Check power and ground connections and repair as needed. |
| LOW FREQUENCY CANCELLATION | Speaker wiring polarity is incorrect | Check speaker polarity and repair as needed. |
| LOW FREQUENCY CANCELLATION (CONT'D) | Crossover settings are incorrect | Reset crossovers referring to the multi-cross crossover configuration section of this manual. |
