Connecting a GAS MAD car audio speaker board
This guide applies to GAS MAD PB1-46, PB1-48, PB2-46 and PB2-48 when connected to a two-channel amplifier.
For a conventional stereo connection, connect the board’s left and right sides to one amplifier channel each. The AST jumpers must remain in place, and the speaker cables must connect to W+ and W− on each side.
Which amplifier do I need?
Use a separate amplifier that supports 2 ohms per channel and has a suitable high-pass filter, HPF.
All models in this guide have a nominal impedance of 2 + 2 ohms. This means the board has two separate speaker sections, each at 2 ohms. With a stereo connection, each amplifier channel used has a 2-ohm load.
Also check that the amplifier’s power suits the particular model. The board must be driven by a separate amplifier and must not be connected directly to the car stereo’s speaker outputs.
What is the AST jumper?
AST stands for Active Smart Terminal. The jumpers link the midbass and tweeter connections so the speakers on each side can be driven by the same amplifier channel.
For conventional two-channel operation, both AST jumpers must be in place. The tweeters’ built-in capacitor filters then attenuate low frequencies.
You do not need to connect the midbass drivers and tweeters separately with this wiring arrangement.
What should I consider before starting?
Disconnect power to the system before working on the connections.
Secure the board properly and mount the amplifier firmly with sufficient ventilation. Route the cables so they are protected against pinching and sharp edges.
Check that all connections are secure and that no loose wire strands could cause a short circuit.
How do I connect power and signal to the amplifier?
The amplifier needs the following connections:
Ground: Start by connecting the ground cable to a suitable, clean, unpainted ground point on the car’s bodywork.
Power: Run a positive cable from the battery to the amplifier. Fit a fuse on the cable no more than 30 cm from the battery.
Audio signal: Connect an RCA cable from the stereo’s preamp output, also called line-out, to the amplifier’s input.
Remote: If the installation uses separate remote control wiring, connect the stereo’s remote output to the amplifier’s remote terminal. This controls the amplifier switching on and off.
The remote wire is often blue/white, but check the correct wire in the stereo’s installation instructions.
Cable cross-sectional area and fuse rating must suit the amplifier and cable routing. Keep the system without power until all connections are complete and checked.
How do I connect the speaker cables to the board?
First check that the AST jumpers are in place on both sides.
Then connect the speaker cables as follows:
Amplifier output |
Connection on the board |
|---|---|
Left channel, positive (+) |
Left side, W+ |
Left channel, negative (−) |
Left side, W− |
Right channel, positive (+) |
Right side, W+ |
Right channel, negative (−) |
Right side, W− |
With this two-channel connection, speaker cables must only connect to the W terminals.
Follow the terminal labels and check polarity. The speaker cables’ negative conductors must connect to the amplifier’s speaker outputs and must not be connected to the car’s bodywork.
How should I set the high-pass filter?
Enable HPF, the high-pass filter, on the channels driving the board. The filter attenuates deep bass and reduces the load on the midbass drivers.
Start with the following settings:
Model |
Midbass driver size |
HPF |
|---|---|---|
GAS MAD PB1-46 |
6.5 inches |
Approximately 120 Hz |
GAS MAD PB1-48 |
8 inches |
Approximately 100 Hz |
GAS MAD PB2-46 |
6.5 inches |
Approximately 120 Hz |
GAS MAD PB2-48 |
8 inches |
Approximately 100 Hz |
Follow the instructions for your model and amplifier. A lower crossover frequency subjects the midbass drivers to more deep bass.
How do I set Bass Boost and Gain?
Set Bass Boost to 0 dB.
Gain matches the amplifier’s input sensitivity to the stereo’s signal level. Start with gain at minimum and follow the amplifier’s instructions for level adjustment.
If the amplifier has a CLIP indicator, use it according to the manual. Reduce the level if the sound becomes distorted.
Turning gain up to maximum does not automatically produce better or cleaner sound and can cause distortion and overloading.
Should I bridge the amplifier?
No. Use a conventional stereo connection, with one side of the board per channel.
An amplifier supporting 2 ohms per channel does not mean it supports 2 ohms in bridged mode. Therefore, do not connect a 2-ohm section to bridged outputs unless the amplifier’s manual explicitly permits that load.
Excessively low load impedance can overload and damage the amplifier.
Can BRL help me with the connections?
Yes! Tell us which GAS MAD board you have and which car stereo and amplifier you use. We can then help check the connections, AST jumpers and suitable settings for your equipment.