PIONEER GM-X252
Service Manual

Connecting the Unit
Connecting the Power Terminal
� Always use the special red battery and ground wire [RD-223], which is sold separately. Connect the battery wire directly to the car battery positive terminal (+) and the ground wire to the car body.

4. Connect the wires to the terminal.
� Fix the wires securely with the terminal screws. GND terminal Power terminal System remote control terminal System remote control wire Ground wire

3. Connect the speaker wires to the speaker output terminals.
� Connect the speaker wires, passing them through the terminal cover. � Fix the speaker wires securely with the terminal screws. Terminal screw

Using the Speaker Input
Connect the car stereo speaker output wires to the amplifier using the supplied speaker input connector.
� Do not connect both the RCA input and the speaker input at the same time.

Connecting the Speaker wires
The speaker output mode can be two-channel (stereo), one-channel (mono), or threechannel (stereo + mono). Connect the speaker leads to suit the mode according to the figures shown below.
� Do not connect both the RCA input and the speaker input at the same time.

Setting the Filter Constant
Three-channel mode, two-way system

Low-pass filter (for subwoofer/woofer): 6 dB/octave
0dB L1 �6dB f

Band-pass filter (combination of low-pass filter and high-pass filter for midbass/mid): 6 dB/octave
L2 C2 0dB �6dB

1. Pass the battery wire from the engine compartment to the interior of the vehicle.
� After making all other connections to the amplifier, connect the battery wire terminal of the amplifier to the positive (+) terminal of the battery. Engine Fuse (30 A) compartment

7 Connections when using the speaker input

C1

Mid-high (Right) Woofer (Mono) Mid-high (Left)
fC 2fC

Two-channel mode (stereo)
Speaker output terminal Terminal cover Car Stereo

L1

C1

High-pass filter (for mid/mid-high): 6 dB/octave
C1 0dB �6dB

fCL 2

fCL

fCH 2fCH

Interior of the vehicle Battery wire

Three-channel mode, three-way system
Speaker output Speaker wire (Right) Speaker (Left)
L2 C1 C2

� A multi-channel system can be set up using a combination of filters. The inductance (L) and capacitance (C) will determine the frequency (fc) that the speaker will reproduce. Refer to the chart below to determine the components required. � Use the capacitors specified. Non-polarized capacitors rated at over ±25 V should be used for C1 and C2 in the diagram. Because of the voltage output of the amplifier, it is very important to use non-polarized capacitors rated at or over 25 V. This will prevent a safety hazard.

Fuse (30 A) Positive terminal Insert the O-ring rubber grommet into the vehicle body.

High/mid-high (Right) Mid/mid-bass (Right) Woofer/subwoofer (Mono) Mid/mid-bass (Left) High/mid-high (Left)

Drill a 14 mm hole into the vehicle body.

Connecting the Speaker Output Terminals
1. Expose the end of the speaker wires using nippers or a cutter by about 10 mm and twist.
Twist

fC 2

fC

f

4. Push on the terminal cover.

L1 L2 C2

2. Twist the battery wire, ground wire and system remote control wire.
Twist
10 mm

White/black: Left � White: Left +

Gray/black: Right � Gray: Right +

One-channel mode (mono)
C1

Component Guide

3. Attach lugs to wire ends. Lugs not supplied.
� Use pliers, etc., to crimp lugs to wires. Lug

2. Attach lugs to speaker wire ends. Lugs not supplied.
� Use pliers, etc., to crimp lugs to wires. Lug Speaker wire

Speaker input connector To speaker input terminal of this unit.

� Inductors (L1 and L2 in the diagrams) act as low-pass filters. Capacitors (C1 and C2 in the diagrams) act as high-pass filters. Inductors (L) are used for the woofer/subwoofer, and capacitors (C)
Speaker (Mono)

Speaker load Impedance
fc (Hz) 50 80 125 200 320 500 800 1,250 2,000 3,200 5,000 8,000 10,000 6.4 4.0 2.5 1.6 1.0 0.64 0.4 0.25 0.16 0.1 0.06 0.04 0.03

2�
L (mH) C (µF) 1,600 1,000 640 400 250 160 100 64 40 25 16 10 8

4�
L (mH) 12.70 8.00 5.10 3.20 2.00 1.30 0.80 0.50 0.30 0.20 0.13 0.08 0.06 C (µF) 800.0 500.0 300.0 200.0 125.0 80.0 50.0 30.0 20.0 12.5 8.0 5.0 4.0

8�
L (mH) 25.50 16.00 10.00 6.40 4.00 2.60 1.60 1.00 0.64 0.40 0.26 0.16 0.13 C (µF) 400.0 250.0 160.0 100.0 62.0 40.0 25.0 16.0 10.0 6.2 4.0 2.5 2.0

are used for the high/mid-high. � Remember when bridging an amplifier it will see only half of the original speaker impedance. Therefore, you must use speakers that have ratings of 4 ohms or higher. If you use speakers that have lower impedance ratings it may cause damage to the amplifier. � When the inductors and capacitors are connected to the speaker wires, secure or solder them so they cannot be pulled loose. Tape or use heat shrink on the joints to prevent short circuits.

Ground wire Lug Battery wire

Three-channel mode (stereo + mono)

The power amplifier is basically a twochannel/one-channel bridgeable amplifier, but three channels can be achieved by combining the stereo and mono modes using inductors and capacitors.