We all use microphones in our audio and music productions. But do you know what is one of the most important tools behind high quality microphone recordings? If you are looking forward to a life long career in the audio world, then you will need to understand various crucial aspects of recording audio. Hence, today we will ask this question – What is a Microphone Preamplifier?
As with all other articles, this one is no different. We will look into the various topics surrounding the microphone preamplifier. Find out more about the core function of this important device. Understand the basic principles in its design and also how it is often used in the professional audio world. Can’t wait to start learning more? Then, let us start right away!
Introduction – Core Function
Microphone preamplifier is a term that either refers to a microphone’s internal electronic circuitry, or to an external device or circuit that the microphone is patched into. However, a microphone preamplifier’s function remain consistent in both cases.
Essentially, a microphone preamplifier is an electronic device that is used in sound engineering, for the purpose of preparing a microphone’s signal for processing by other audio devices. Signals from microphones are typically too weak to retain its quality, before being transmitted to other recording devices (such as mixing consoles).
Preamplifiers work by providing a stable supply of gain and at the same time, prevents noise interferences that may distort the signal. This ultimately increases the microphone’s signal to line level, which is the level of signal strength that is needed by other audio equipment for processing.
Other common terms that are used to identify a microphone preamplifier includes: microphone preamp, mic preamp, preamp (not the same as a control amplifier in high-fidelity reproduction equipment), mic pre and pre.
The topics that we are going to discuss further, are as follows:
- Technical aspects
- Main function
- Impact on recording
A dynamic microphone often produces a very low output voltage, usually ranging between 1 to 100 microvolt. A microphone preamplifier will normally increase that level by up to 70 dB (anywhere up to 10 volts). The audio signal will then be strong enough to be processed by various equipment.
The amplified microphone signal (after going through the preamplifier) can then be used to drive equalization circuitry within an audio mixer, to drive external audio effects processors, and to sum with other signals in the creation of a final audio mix for studio recording or for live performances.
Not only does a microphone preamplifier provides gain for the microphone signal, it is also often integrated into mixing consoles or designed to be a discrete component which functions to provide phantom power to microphones (typically condenser microphones).
Impact on Recording
Microphones, being transducers themselves, are the major source of coloration in an audio signal. Most audio professionals would agree that a microphone preamplifier will also affect the sound quality of the recording. Using a preamplifier might cause the microphone to work harder, as it may be loaded with low impedance. This ultimately alters its tonal quality.
Various preamplifiers with different designs, may induce unique colorations by adding different characteristics as compared to an audio mixer’s built-in preamplifiers. There are some microphones that must driven by a preamplifier, in order to function properly (for instance, condenser microphones).
When you look at a mixing desk or console, the microphone preamplifier exist as one part of a channel strip (usually controlled by a “gain” knob at the very top), which can also feature other integrated signal processors such as compressors, equalization (EQ), noise gates, and enhancers.
With that, with have come to the end of this article. Learnt something new today? Well I hope you now have a better understanding of this vital audio device!
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