Trouble Shooting

The key to finding the problem in a misbehaving sound system is to isolate parts of that system in a logical fashion to track down the fault.

Description of the Diagnostic system built into all MB Quart amplifiers

The diagnostic system will shut down the amplifier, until reset by turning the head unit off, and back on. This state of affairs will be indicated by the front panel PROTECT LED lighting up under the following conditions:

1 - A short circuit on the loudspeaker leads.

2 - An internal amplifier fault that causes a DC offset on the loudspeaker output.

Should the amplifier go into diagnostic mode, simply disconnect all RCA and speaker leads, while keeping +12 volt, power ground and remote leads connected.

1.Now turn the amplifier back on, and if the diagnostic LED lights, the amplifier has an internal fault.

2.If not, plug the RCA cables back, and reset the amplifier. If it goes into diagnostic now, the fault lies in the input, either with bad cables or source unit.

3.If the amplifier seems fine with RCA cables plugged in, connect the speakers, one at a time, and if one of the speakers or its wiring is faulty, it will activate the diagnostic system.

Amplifier heatsink overheating

The amplifiers will shut down when the heatsink temperature reaches 80 degrees centigrade, and turn back on once the unit has cooled down below that point. Causes of overheating:

1 - Inadequate cooling - relocate or remount to provide better natural airflow over the fins.

2 - Driving high power levels into low impedances - back off on the volume control, and/or make sure you are not loading the amplifier with less than the recommended loudspeaker impedance.

Low output power

1 - Check that level controls have been set up properly.

2 - Make sure that the battery voltage, as measured at the amplifier’s +12 volt and ground terminals, is 11 volts or more. 3 - Check all +12 volt and ground connections.

Fuses blowing

1 - The use of loudspeaker impedances below the recommended minimums will draw more current - check. 2 - A short on the main +12 volt cable from the battery to the vehicle chassis will cause the main fuse to blow.

System does not turn on 1 - Check all fuses.

2 - Check all connections.

3 - Measure the +12 volt and remote turn on voltages at the amplifier terminals. If these are non existent or low, take voltage measurements at fuse holders, distribution blocks, the head unit’s +12 volt and remote leads to localize the problem.

Noise problems

System noise can be divided into two categories, hiss, and electrical interference.

Hiss, or white noise

1 - High levels of white noise usually occurs when amplifier level controls are turned up too high - readjust according to the procedures in section ”Setting up systems after installation for best performance”

2 - Another major problem that can cause excessive hiss, is a noisy head unit - unplug the amplifier input RCA cables, and if the hiss level reduces, the source unit is at fault.

Electrical interference

The inside of an automobile is a very hostile electrical environment. The multitude of electrical systems, such as the ignition system, alternator, fuel pumps, air conditioners, to mention just a few, create radiated electrical fields, as well as noise on the +12 volt supply and ground. Remember to isolate the problem - first unplug amplifier input RCA cables, if the noise is still present, check the speaker leads, if not, plug the RCA’s back, and investigate the source driving the amplifier, one component at a time.

A ticking or whine that changes with engine RPM:

1 - This problem could be caused by radiation pickup of RCA cables too near to a fuel pump or a distributor, for instance, - relocate cables.

2 - Check that the head unit ground is connected straight to the vehicle chassis, and does not use factory wiring for ground.

3 - Try to supply the head unit with a clean +12 volt supply directly from the battery +, instead of using a supply from the in dash wiring/fusebox.

A constant whine:

This type of noise can be more difficult to pinpoint, but is usually caused by some kind of instability, causing oscillations in the system. 1 - Check all connections, especially for good grounds.

2 - Make sure that no speaker leads are shorting to exposed metal on the vehicle chassis.

3 -RCA cables are notorious for their problematic nature, so check that these are good, in particular the shield connections.

ONX1.1500D, ONX4.125, ONX4.80/500, ONX1.1000D, ONX4.80 specifications

MB Quart, a renowned name in the audio industry, has made a significant impact with its ONX series, which includes models like the ONX4.80, ONX4.60, ONX2.100, ONX1.1000D, and ONX4.80/500. These amplifiers are designed to deliver powerful audio performance while being versatile enough to cater to various needs in the automotive sound sector.

The ONX4.80 is a 4-channel amplifier capable of delivering a robust 80 watts RMS per channel at 4 ohms, showcasing a total power output of 500 watts. This model incorporates a unique class-D topology that provides high efficiency and low distortion, ensuring that users can enjoy crisp sound quality without draining their vehicle’s power supply. Its compact design allows for easy installation in tight spaces, making it an ideal choice for both experienced installers and DIY enthusiasts.

Meanwhile, the ONX4.60, a slightly smaller 4-channel amplifier, offers 60 watts RMS per channel at 4 ohms, with a similar class-D configuration. This amplifier is particularly well-suited for users looking to power smaller speaker setups or as part of a multi-amplifier system. Its low-profile design and excellent thermal management features further enhance its performance, providing reliable power during extended listening sessions.

For those in need of monoblock power, the ONX1.1000D stands out with its impressive ability to deliver 1,000 watts RMS at 1 ohm. This amplifier is engineered to drive subwoofers with ease, thanks to its high-efficiency operation and comprehensive thermal protection circuitry. The ONX1.1000D also features an adjustable low-pass filter and bass boost controls, allowing users to tailor their low-frequency output to suit their specific preferences.

The ONX2.100, a 2-channel amplifier, rounds out the range with a strong 100 watts RMS per channel at 4 ohms. It is perfect for driving full-range speakers or as part of a larger multi-channel setup. Like its counterparts, the ONX2.100 employs advanced circuitry for low noise and high fidelity, making it an excellent choice for any audio enthusiast looking to enhance their vehicle’s sound system.

Collectively, the ONX series amplifiers from MB Quart embody robust performance, compact design, and superior technology, making them an ideal choice for anyone looking to elevate their automotive audio experience. Whether users seek powerful lows, clear mids, or crisp highs, there is an ONX model tailored to meet those needs while maintaining reliability and efficiency.