Premier Service Center Certification: Advanced Amplifiers

QSC does offer power amplifiers with Class D output circuitry technology.

In the AC Line Filter circuit of QSC's switch mode power supply, a slow blow fuse is used. This type of fuse is designed to withstand short high current bursts without blowing immediately. It has a delayed response to high current, allowing it to handle temporary surges without interrupting the circuit. This is important in switch mode power supplies where there can be sudden changes in current flow. Using a fast blow fuse would result in frequent blowing and interruption of the power supply. The specific current rating of the fuse is not mentioned in the question.

In a Class D amplifier, the power dissipation is low during higher signal levels because the output transistors are either fully on or fully off. This means that they are not in the linear region where they would dissipate significant power. Instead, they switch rapidly between these two states, resulting in very little power loss. This switching behavior allows Class D amplifiers to achieve high efficiency and minimize power dissipation, making them more efficient than Class A, B, AB, and H amplifiers.

The power supply IGBTs in QSC's switch-mode PLC platform switch on and off at a frequency of 110 kHz.

The step driver in a Class H amplifier is a comparator. A comparator is a circuit that compares two voltage inputs and outputs a digital signal based on the comparison. In the case of a Class H amplifier, the comparator is responsible for turning the MOSFET switch on and off to control the amplification of the audio signal. It compares the input voltage with a reference voltage and generates the appropriate control signal to switch the MOSFET.

IC U18 is a driver IC that provides valid gate drive pulse trains to the IGBTs. This means that it controls the timing and amplitude of the signals that are sent to the IGBTs, which are insulated-gate bipolar transistors. The IGBTs are responsible for switching the high voltage power supply on and off, and the driver IC ensures that the signals are accurate and reliable.

The switch-mode power supply in the PLX2-04 models and GX7 are simplified versions of the PLC platform of amplifiers. This means that the power supply in these models has been simplified and designed based on the PLC platform, which is a type of amplifier platform.

In Class D technology, the switching frequency refers to how quickly the audio signal is converted into a digital waveform. The switching frequency needs to be at least 10 times faster than the highest audio frequency to accurately reproduce the audio signal. This is because the switching frequency determines the resolution and fidelity of the digital waveform, ensuring that all the nuances and details of the audio are captured and reproduced faithfully.

A Class H output circuitry has the disadvantage of requiring more components compared to other types of output circuitry. This means that the circuitry becomes more complex and potentially more expensive to manufacture and maintain.

The purpose of the housekeeping supply circuit in the PLC platform is to provide the operating voltages for components within the power supply. This circuit ensures that all the necessary components receive the correct voltage for their operation, ensuring the proper functioning of the power supply. It is responsible for supplying power to various components such as relays, sensors, and other electrical devices within the power supply system.

In a Class D amplifier, the switching transistors are driven by a Pulse Width Modulated (PWM) signal. This means that the amplitude of the signal remains constant, but the width of the pulses varies according to the input audio signal. This allows for efficient power conversion and high fidelity audio reproduction. The PWM signal is generated by comparing the input audio signal with a high frequency carrier signal and adjusting the width of the pulses accordingly.

In the PL380 video orientation by Pat Quilter, there are two relays that click on the PL380 before the amplifier comes out of muting and is ready to go.

IC U19 is a controller IC that generates alternating signals for the gate driver IC. This means that it is responsible for controlling the timing and frequency of the signals that tell the IGBTs when to turn off and on. By generating these alternating signals, IC U19 ensures that the power supply operates efficiently and effectively.

The primary purpose of the MOSFET in a Class H amplifier is to switch the output to a higher voltage rail. This is achieved by controlling the flow of current through the MOSFET, which allows the amplifier to efficiently amplify the input signal to a higher voltage level. By switching the output to a higher voltage rail, the MOSFET helps to increase the overall power output of the amplifier.

QSC's most widely used switch-mode power supply platform is called "PLC."

The "I" in IGBT stands for "Insulated." IGBT stands for Insulated Gate Bipolar Transistor, which is a type of semiconductor device used for power control and switching applications. The term "Insulated" refers to the fact that the gate of the IGBT is electrically isolated from the rest of the device, allowing for better control and protection against voltage spikes.

In the PLC platform of amplifiers, there are several types of protect circuits that exist in the power supply. These include AC Loss, which protects against the loss of AC power supply; Undervoltage, which protects against voltage levels below the acceptable range; Overcurrent, which protects against excessive current flow; and DC Fault, which protects against faults in the DC power supply. These protect circuits help ensure the proper functioning and safety of the amplifier system.

A Class H output circuitry uses 2 or more bipolar supply rails. This means that it requires at least two supply rails, with one being positive and the other being negative. The use of bipolar supply rails allows for the amplification and output of audio signals with both positive and negative voltage swings, providing more flexibility and dynamic range in the audio output.

IC U13 pins 8 and 9 compare the bridge rectifier input voltage to detect loss of AC.

A low-pass reconstruction filter is used in a Class D amplifier to smooth the PWM (Pulse Width Modulation) pulse train back into an audio signal. This filter allows only the lower frequency components of the signal to pass through, while attenuating the higher frequency components. By doing so, it removes the high-frequency switching noise of the PWM and reconstructs a clean audio signal that can be amplified and reproduced by the speaker.

The correct answer is Class D output devices and auxiliary devices. In the PL380 video orientation by Pat Quilter, the largest heatsink is covering these components. Class D output devices are responsible for amplifying the audio signal, while auxiliary devices provide additional support and functionality to the amplifier. These components generate heat during operation, which is why they are placed under the largest heatsink to dissipate the heat effectively and prevent overheating.

The comparator in a step driver of a Class H amplifier compares the trigger and reference voltages. The trigger voltage is the input signal that initiates the switching action, while the reference voltage is the threshold level that the trigger voltage is compared against. When the trigger voltage exceeds the reference voltage, the comparator triggers the switching action in the amplifier.

In the PLC platform's switching power supply circuit, the input AC energy is rectified to DC using a bridge rectifier. A bridge rectifier is a circuit that converts alternating current (AC) to direct current (DC). It consists of four diodes arranged in a bridge configuration. The diodes allow the current to flow in only one direction, effectively converting the AC input into a pulsating DC output. This rectified DC output is then used to power the various components of the PLC platform.

Class D technology refers to a type of amplifier that uses pulse width modulation (PWM) to deliver high power audio signals efficiently. One of the problems with Class D technology is that rail noise and voltage fluctuations can affect the quality of the signal being amplified. This can result in distortion or other unwanted artifacts in the audio output. Another problem is the dead time between positive and negative pulses, which can cause distortion or audible artifacts in the audio signal. Therefore, the correct answers are "Rail noise and voltage fluctuations affecting signal" and "Dead time between positive and negative pulses".

A Class H output circuitry offers advantages such as being more efficient and having reduced current consumption. This means that it can deliver power more effectively and consume less energy, resulting in improved overall performance and energy savings. However, the statement "More components" is not correct as Class H circuitry typically involves fewer components compared to other circuit designs. Additionally, the statement "Easy to troubleshoot" is not applicable as the ease of troubleshooting depends on various factors and cannot be solely attributed to the use of Class H circuitry.

The power supply in the PLC platform of amplifiers protects from overcurrent by measuring the average current draw and reducing the load on the power supply. This means that when the current draw exceeds a certain threshold, the power supply automatically adjusts the load to prevent any damage or failure. By monitoring and regulating the current draw, the power supply ensures the safe and efficient operation of the amplifiers.

A Class AB output circuitry typically uses only one bipolar supply rail. This means that there is one positive (+) rail and one negative (-) rail, which are counted as a single rail. This type of circuitry is commonly used in audio amplifiers and other applications where high power and low distortion are required. By using a single bipolar supply rail, the circuit can efficiently amplify both positive and negative signals without requiring additional power supplies.

The QSC amplifiers that were developed with the PLC switch-mode power supply platform are PLX, DCA, and Powerlight 2.

The positive step driver in a class H amplifier differs from the negative step driver by having a bootstrap power supply. This means that the positive step driver utilizes a circuit that allows the voltage to be boosted or "bootstrapped" to a higher level, which can improve the efficiency and performance of the amplifier. In contrast, the negative step driver does not have this feature.

A 2-tier Class H amplifier should have 1 pair of step drivers. This is because a 2-tier amplifier consists of two stages, and each stage requires a pair of step drivers to control the voltage supply. Therefore, there should be a total of 1 pair of step drivers in a 2-tier Class H amplifier.

QSC amplifiers use 2-tier, 3-tier, and 4-tier Class H output circuitry. Class H amplifiers are designed to improve efficiency by using multiple power supply rails. The tiers refer to the number of voltage levels used in the amplifier's output stage. In a 2-tier configuration, there are two voltage levels, while a 3-tier configuration has three voltage levels, and a 4-tier configuration has four voltage levels. By using multiple tiers, QSC amplifiers can optimize power usage and reduce distortion, resulting in improved performance and efficiency.