Handbook for Sound Engineers

This page intentionally left blank ...

733 Chapter 21 Preamplifiers and Mixers by Bill Whitlock and Michael Pettersen 21.1 Microphone Preamplifier Fundamentals........ ...

734 21.3.4.7 Automatic Microphone Mixers with Matrix Mixing to Multiple Outputs..................... 752 21.3.4.8 Automatic Mixi ...

Preamplifiers and Mixers 735 21.1 Microphone Preamplifier Fundamentals Microphones are transducers that typically have very low ...

736 Chapter 21 then 20 × log 0.91, which is 0.8 dB. Generally, loading loss is negligible (under 1 dB) if load impedance is ten ...

Preamplifiers and Mixers 737 To a greater or lesser degree, the frequency response of any microphone will be affected by the loa ...

738 Chapter 21 with resistor material and construction. Note that only the resistive portion of impedance generates noise— pure ...

Preamplifiers and Mixers 739 to achieve a DLP of 5° or less from 20 Hz to 20 kHz, frequency response must extend from 0.87 Hz to ...

740 Chapter 21 20 Hz–20 kHz, giving it truly excellent waveform fidelity and square-wave response. As discussed in detail in Cha ...

Preamplifiers and Mixers 741 transformers on main inputs and outputs, built-in stereo limiter, input overload indicators, select ...

742 Chapter 21 be considered when the number of microphones required for the sound system is four or greater. When used in a sou ...

Preamplifiers and Mixers 743 increases. All audio systems face the same problems whenever multiple open microphones are needed. ...

744 Chapter 21 21.3.1.4 Summary Keeping the number of open microphones to a minimum always improves overall audio quality. The ...

Preamplifiers and Mixers 745 An automatic microphone mixer cannot improve the performance of microphones. Its primary benefit co ...

746 Chapter 21 Permanent Activation of an Input Channel. In a house of worship, a microphone over the congregation could be kept ...

Preamplifiers and Mixers 747 (21-3) where, N is the number of activated microphones. While NOMA helps maintain stable gain in a ...

748 Chapter 21 simple level compression circuits. If there is no signal, the AGC gain holds at its last value. 21.3.4 Types of A ...

Preamplifiers and Mixers 749 all microphones in the system must be below some maximum value that avoids feedback oscillation. Th ...

750 Chapter 21 21.3.4.4 Direction-Dependent Automatic Microphone Mixers A direction-dependent automatic microphone mixer respond ...

Preamplifiers and Mixers 751 manufactured by Shure, including the now obsolete FP410 battery-operated portable mixer, Fig. 21-21 ...