Sony XM-N502 - Stereo Power Amplifier Operating Manual

Features

• Maximum power output of 150 W per channel (at 4 Ω).
• This unit can be used as a monaural amplifier with a maximum output of 500 W.
• Dual mode connection possible for a multi-speaker system.
• Built in Low-pass filter (80 Hz, 18 dB/oct).
• Protection circuit and indicator provided.
• Hi-level Sensing Power On feature allows unit to be activated without need for REMOTE connection.
• Pulse power supply* for stable and regulated output power.
• Direct connection can be made with the speaker output of your car audio unit if it is not equipped with the line output (High level input connection).

* Pulse power supply
This unit has a built-in power regulator which converts the power supplied by the 12 V DC car battery into high speed pulses using a semiconductor switch. These pulses are stepped up by the built-in pulse transformer and separated into both positive and negative power supplies before being converted into direct current again. This is to regulate fluctuating voltage from the car battery. This light weight power supply system provides a highly efficient power supply with a low impedance output.

Specifications

Design and specifications are subject to change without notice.

CEA2006 Standard
Power Output: 65 Watts RMS × 2 at 4 Ohms <1% THD+N
SN Ratio: 93 dBA (reference: 1 Watt into 4 Ohms)

Dimensions

Unit: mm

Location and Function of Controls

1. LEVEL adjustment control
   The input level can be adjusted with this control. Turn it in the clockwise direction when the output level of the car audio unit seems low.
2. LPF switch
   When the LPF switch is set to ON, the Low-pass filter (80 Hz) is effective.
3. POWER/PROTECTOR indicator
   Lights up in green during operation. When the PROTECTOR is activated the indicator will change from green to red. When the PROTECTOR is activated refer to the Troubleshooting Guide.

Precautions

• This unit is designed for negative ground 12 V DC operation only.
• Use speakers with an impedance of 2 to 8 Ω (4 to 8 Ω when used as a bridging amplifier).
• Do not connect any active speakers (with built-in amplifiers) to the speaker terminals of the unit. Doing so may damage the active speakers.
• Avoid installing the unit in areas subject to:
  • high temperatures such as from direct sunlight or hot air from the heater.
  • rain or moisture.
  • dust or dirt.
• If your car is parked in direct sunlight and there is a considerable rise in temperature inside the car, allow the unit to cool down before use.
• When installing the unit horizontally, be sure not to cover the fins with the floor carpet etc.
• If this unit is placed too close to the car audio unit or aerial, interference may occur. In this case, relocate the amplifier away from the car audio unit or aerial.
• If no power is being supplied to the car audio unit, check the connections.
• This power amplifier employs a protection circuit* to protect the transistors and speakers if the amplifier malfunctions. Do not attempt to test the protection circuits by covering the heat sink or connecting improper loads.
• Do not use the unit on a weak battery as its optimum performance depends on a good power supply.
• For safety reasons, keep your car audio unit volume moderate so that you can still hear sounds outside your car.

* Protection circuit
This amplifier is provided with a protection circuit that operates in the following cases:

• when the unit is overheated
• when a DC current is generated
• when the speaker terminals are short-circuited.

The colour of the POWER/PROTECTOR indicator will change from green to red, and the unit will shut down.
If this happens, turn off the connected equipment, take out the cassette tape or disc, and determine the cause of the malfunction. If the amplifier has overheated, wait until the unit cools down before use.

Fuse Replacement

If the fuse blows, check the power connection and replace the fuse. If the fuse blows again after replacement, there may be an internal malfunction. In such a case, consult your nearest Sony dealer.

Warning

When replacing the fuse, be sure to use one matching the amperage stated above the fuse holder. Never use a fuse with an amperage rating exceeding the one supplied with the unit as this could damage the unit.

If you have any questions or problems concerning your unit that are not covered in this manual, please consult your nearest Sony dealer.

Connections

Cautions

• Before making any connections, disconnect the ground terminal of the car battery to avoid short circuits.
• Be sure to use speakers with an adequate power rating. If you use small capacity speakers, they may be damaged.
• This is a Phase-Inverted Amplifier.
• Do not connect the terminal of the speaker system to the car chassis, and do not connect the terminal of the right speaker with that of the left speaker.
• Install the input and output cords away from the power supply wire as running them close together can generate some interference noise.
• This unit is a high powered amplifier. Therefore, it may not perform to its full potential if used with the speaker cords supplied with the car.
• If your car is equipped with a computer system for navigation or some other purpose, do not remove the ground wire from the car battery. If you disconnect the wire, the computer memory may be erased. To avoid short circuits when making connections, disconnect the +12V power supply wire until all the other wires have been connected.

Parts for Installation and Connections

Installation

Before Installation

• Mount the unit either inside the trunk or under a seat.
• Choose the mounting location carefully so the unit will not interfere with the normal movements of the driver and it will not be exposed to direct sunlight or hot air from the heater.
• Do not install the unit under the floor carpet, where the heat dissipation from the unit will be considerably impaired.

Mount the unit

First, place the unit where you plan to install it, and mark the positions of the 4 screw holes on the mounting board (not supplied). Then drill a 3 mm pilot hole at each mark and mount the unit onto the board with the supplied mounting screws. The mounting screws are all 20 mm long, so make sure that the mounting board is thicker than 20 mm.

Power connections

Make the terminal connections

Pass the wires through the cap, connect the wires, then cover the terminals with the cap.

Note
When you tighten the screw, be careful not to apply too much torque* as doing so may damage the screw.
* The torque value should be less than 1 N•m.

Make the power connections

*¹ If you have the factory original or some other car audio unit without a remote output for the amplifier, connect the remote input terminal (REMOTE) to the accessory power supply. In High level input connection, car audio unit can also be activated without need for REMOTE connection. However, this function is not guaranteed for all car audio units.

Notes on the power supply

• Connect the +12V power supply wire only after all the other wires have been connected.
• Be sure to connect the ground wire of the unit securely to a metal point of the car. A loose connection may cause a malfunction of the amplifier.
• Be sure to connect the remote control wire of the car audio unit to the remote terminal.
• When using a car audio unit without a remote output on the amplifier, connect the remote input terminal (REMOTE) to the accessory power supply.
• Use a power supply wire with a fuse attached (25 A).
• All power wires connected to the positive battery post should be fused within 450 mm of the battery post, and before they pass through any metal.
• Make sure that the vehicle's battery wires connected to the vehicle (ground to chassis)*² are of a wire gauge at least equal to that of the main power wire connected from the battery to the amplifier.
• During full-power operation, a current of more than 25 A will run through the system. Therefore, make sure that the wires to be connected to the +12V and GND terminals of this unit are at least 14-Gauge (AWG-14) or have a sectional area of more than 2 mm².

Input Connections

For details on input connections, see below

Line Input Connection (with Speaker Connection)

Line Input Connection (with Speaker Connection)

High Level Input Connection (with Speaker Connection)

High Level Input Connection (with Speaker Connection)

High Level Input Connection (with Speaker Connection)

Speaker Connections

Turn on or off the LPF switch at the unit rear. For details on speaker connections, see below

2-Speaker System (with Input Connection)

Subwoofer (with Input Connection)

Note
If you wish to use a subwoofer as the monaural speaker, connect the speaker as illustrated above. The output signals to the subwoofer will be the combination of both right and left output signals.

1-Speaker System (with Input Connection)

Note
Make sure that the line output from the car audio unit is connected to the jack marked "L (BTL)" on the unit.

Dual Mode System (with a Bridged Subwoofer)

Table of crossover values for 6 dB/ octave (4 Ω) (Speaker Connections)

* Not supplied

Notes

• When using passive crossover networks in a multi-speaker system, care must be taken as the speaker system's impedance should not be lower than that of the suitable impedance for this unit.
• When you are installing a 12 decibels/octave system in your car, the following points must be considered. In a 12 decibels/octave system where both a choke and capacitor are used in series to form a circuit, great care must be taken when they are connected. In such a circuit, there is going to be an increase in the current which bypasses the speaker with frequencies around the crossover frequency. If audio signals continue to be fed into the crossover frequency area, it may cause the amplifier to become abnormally hot or the fuse to blow. Also if the speaker is disconnected, a series-resonant circuit will be formed by the choke and the capacitor. In this case, the impedance in the resonance area will decrease dramatically resulting in a short circuit situation causing damage to the amplifier. Therefore, make sure that a speaker is connected to such a circuit at all times.

Troubleshooting Guide

The following checklist will assist in the correction of most problems which you may encounter with your unit.
Before going through the checklist below, refer to the connection and operating procedures.

The POWER/PROTECTOR indicator does not light up

• The fuse is blown. Replace the fuse with a new one.
• The ground wire is not securely connected. Fasten the ground wire securely to a metal point of the car.
• The voltage going into the remote terminal is too low.
  • The connected car audio unit is not turned on. Turn on the car audio unit.
  • The system employs too many amplifiers. Use a relay.
• Check the battery voltage (10.5 – 16 V).

The POWER/PROTECTOR indicator will change from green to red

• Turn off the power switch. The speaker outputs are shorted. Rectify the cause of the short.
• Turn off the power switch. Make sure the speaker cord and ground wire are securely connected.

The unit becomes abnormally hot

• Use speakers with suitable impedance. 2 – 8 Ω (stereo), 4 – 8 Ω (when used as a bridging amplifier).
• Make sure to place the unit in a well ventilated location.

The sound is interrupted

• The thermal protector is activated. Reduce the volume.

Alternator noise is heard

• The power connecting wires are installed too close to the RCA pin cords. Keep the wires away from the cords.
• The ground wire is not securely connected. Fasten the ground wire securely to a metal point of the car.
• Negative speaker wires are touching the car chassis. Keep the wires away from the car chassis.

The sound is muffled

• The LPF switch is set to the "OFF" position. When connecting the full range speaker, set to "OFF" position.

The sound is too low

• The LEVEL adjustment control is not appropriate.
  Turn the LEVEL adjustment control in the clockwise direction.

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Documents / Resources

References

• Sony Corporation - Home

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