QSC Audio CX Series user manual IX. Designing the Distributed Sound System

Page 21
sensitivity = 92 dB, 1 watt@1m
1 meter
2 meters
1watt in

IX. Designing the Distributed Sound System

There are several main steps in designing a distributed sound system:

•Determining loudspeaker coverage and placement

•Determining power levels for each loudspeaker

•Choosing the right amplifier

LOUDSPEAKER COVERAGE AND PLACEMENT

The goal in placing the loudspeakers in a distributed system is to acoustically cover the required area effectively but economically. An effective coverage would be one where the sound from the system’s loudspeakers is not only audible, but intelligible, over all of the area. An economical coverage would be one that achieves the goal with the fewest loudspeakers necessary.

A loudspeaker in a partially or fully enclosed area produces two sound fields: the direct field, which is sound coming directly “line-of-sight” from the loudspeaker; and the diffuse field, which is sound from the loudspeaker which has reflected off of surfaces in the area, such as floors, walls, tables, ceilings, etc. The direct sound field decreases with distance from the loudspeaker; every time you double the distance, the sound pressure level drops 6 dB. This is called the Inverse Square Law because the result of a 6 dB sound pressure level decrease is the same as 1/4 of the sound intensity (i.e., the sound power per square centimeter), which varies inversely with the square of the distance.

Even though it too is subject to the Inverse Square Law, the intensity of the diffuse field is more difficult to predict, especially with multiple acoustically reflective surfaces. The problem

is that moving away from one surface may also be moving closer

to another. Controlling the diffuse field often involves architectural planning as well as acoustical treatment with absorptive surface materials.

To maintain intelligibility, maximize the ratio of direct field to diffuse field; this generally involves placing

92 dB SPL

3 meters

the loudspeakers as close to the listeners as is both physically and economically prac- tical.

86 dB SPL

4 meters

Sometimes, a distributed line system can help a coverage area with difficult acoustical char- acteristics. For example, a very re- verberant room with all large hard,

82.5 dB SPL

80 dB SPL

20

Page 20 Page 22
Image 21
Page 20 Page 22
Contents CX Series Table of Contents Explanation of Graphical Symbols Lifting Precautions Rack Mounting PrecautionsSpeaker Damage Speaker Output Shock HazardPortable rack II. Overall DescriptionCX4 IV. Outputs III. InputsInput Sensitivities Caused by a floating inputOutput connections for CX, bridged mono mode Controls & Displays AC PowerVI. Operation CX4 and CX4TCX6, CX6T, CX12 and CX12T TroubleshootingCX6, CX6T, CX12 & CX12T Problem OverheatingPage CX4 and CX4T BRIDGED-MONO Mode CautionAC Current Consumption Maximum LONG-TERM Output PowerHeat Emissions Protection Circuits Frequency Response VII. SpecificationsDamping Factor Output RegulationVoltage Gain Power RequirementsInput SENSITIVITY, Vrms Input ImpedanceWeight DimensionsVIII. Distributed lines Line for different power levelsIX. Designing the Distributed Sound System Loudspeaker Coverage and PlacementPage Determining Power Levels IntelligibilityRequires Example Selecting the AmplifierUsing Components with Different Voltages Watts for the speakers How Many Speakers?25 x 1.25 = Or 64 speakers tapped at 5 watts, etcSpeaker Transformer Saturation XI. Other Design ConsiderationsPower Transfer Coefficient = RLOAD/RWIRE + RLOAD2 Wire LossPage Heat Emissions XII. Address & Telephone Information

CX Series specifications

QSC Audio, a recognized leader in professional audio solutions, presents the CX Series of amplifiers, a fusion of power, efficiency, and cutting-edge technology designed to meet the demands of various sound reinforcement applications. Known for their reliability and outstanding performance, the CX Series amplifiers are perfect for installations in venues, theaters, and houses of worship, delivering high-quality audio reproduction regardless of the setting.

At the core of the CX Series is its robust Class D amplification. This technology not only ensures excellent audio fidelity but also enhances energy efficiency, resulting in lower operational costs and cooler running temperatures. The amplifiers utilize a linear power supply, which contributes to exceptional audio quality by providing stable and clean power to the components. With varying power ratings, including options ranging from 200 to 1200 watts per channel, the CX Series caters to different venue sizes and specific audio requirements.

The CX Series is engineered with a range of features that enhance usability and performance. Integrated DSP (Digital Signal Processing) allows users to access advanced sound processing algorithms, enabling fine-tuning of audio settings for optimal performance. The amplifiers include comprehensive protection circuitry to safeguard the equipment from thermal overload, short circuits, and signal clipping, ensuring longevity and reliability in demanding environments.

Connectivity is also a significant aspect of the CX Series. The amplifiers are equipped with a variety of input and output options, including XLR, 1/4" TRS, and barrier strip connectors, facilitating seamless integration with a wide range of audio sources and speakers. Moreover, the user-friendly interface includes LCD displays for easy monitoring, making setup and adjustments straightforward for audio engineers and technicians.

Another defining feature of the CX Series is its lightweight design. This portability makes installation and transport easy without compromising on performance. Additionally, QSC’s commitment to sustainability is evident in the design, as the amplifiers are constructed with environmentally friendly materials and have a reduced carbon footprint, aligning with modern practices in eco-conscious audio engineering.

In summary, the QSC Audio CX Series amplifiers blend professionalism with versatility, delivering exceptional performance that satisfies both audio quality and operational reliability. Their innovative technologies and thoughtful design make them a powerful ally for professionals in any sound reinforcement scenario.
Top Page Image Contents