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.	5

NAU460, NAU660, NAU260 specifications

MB Quart has long been synonymous with high-performance audio systems, and their NAU series—specifically, the NAU660, NAU460, and NAU260—continues this legacy. Each model in the NAU series is engineered to provide superior sound quality and robust performance, making them ideal choices for car audio enthusiasts and home audio applications alike.

The NAU660 is the flagship model of the series, featuring a powerful power output of 600 watts. This model is designed to deliver crystal-clear sound across a wide frequency range, ensuring that every note and beat is faithfully reproduced. The NAU660 includes advanced Class D amplification technology, which not only enhances sound efficiency but also reduces heat generation, leading to increased longevity of the unit.

Next in line is the NAU460, which offers a balance between performance and affordability. With a power output of 400 watts, this model doesn't compromise on sound quality. It features high-quality components, including custom-engineered driver elements designed to deliver deep bass and clear highs. The NAU460 is particularly suitable for users looking to upgrade their factory audio systems without breaking the bank.

Lastly, the NAU260 is a versatile model that caters to compact car audio setups. With a power output of 260 watts, it is designed for urban drivers who want a quality audio experience without the bulk. Despite its smaller size, the NAU260 boasts impressive sound reproduction with enhanced bass response, making it perfect for modern music genres.

All three models feature user-friendly controls, allowing for easy adjustments to suit individual listening preferences. The sleek design ensures that they seamlessly integrate into any audio setup, whether in a vehicle or a home theater system. Additionally, these models incorporate various protection circuits to safeguard against overheating and short circuits, ensuring safe operation during extensive use.

The MB Quart NAU series is equipped with high-pass and low-pass crossover technologies, enabling users to optimize frequency output based on speaker configurations. This feature enhances the overall audio experience, ensuring that the right frequencies reach the right speakers.

In summary, the MB Quart NAU660, NAU460, and NAU260 each deliver impressive audio performance, tailored to meet the varying needs of audio enthusiasts. With advanced technology and robust design, these models exemplify MB Quart's commitment to innovation in sound quality. Whether for everyday use or a high-performance system, the NAU series stands out as a reliable choice.

TROUBLE SHOOTING

A ticking or whine that changes with engine RPM:

A constant whine:

NAU460, NAU660, NAU260 specifications