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What is a Microphone Preamplifier? – A Vital Device!

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.

Neve Mic Pre Compressor

Portico 5015 Mic Pre Compressor / Photo by Hens Zimmerman / CC BY 2.0

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.

Noise Interference

Photo by Ian Gregory / CC BY 3.0

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

Technical Aspects

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.

ADC

In this case, the mic preamp is inside the computer / Photo by Teeks99 / CC BY-SA 3.0

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.

Main Function

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.

Mixer Preamp

Mixing console mic preamps / Photo by Bubba73 at English Wikipedia / CC BY-SA 3.0

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!

Do leave a comment or question below, and share this article if you have benefited from it!

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Farhan

When I'm not rocking out to great music, I'd prefer to be sleeping on a field on a windy day =)

6 Comments

  1. It’s been a while since I thought anything about the different components that make up a sound system for the type of mic you may be using and what requirements the pre-amps of the mic may be.

    The part I like nowadays with the technology being used is the added feature of having wireless mics.

    Do you still prefer the older style of corded mics or do you find the wireless are better these days?

    • Hello Travis!

      There are advantages and disadvantages when using wireless. Many prefer the wireless for the most obvious reason, which is convenience. However it does come at the cost of having possible radio interference, limited transmission range (depending on model), relatively short battery life etc.

      For me, it really depends on the application. For most corporate shows where the usage duration for each session with the microphone is often short, then wireless mics are preferred. However in a music festival where bands are performing sets of at least an hour each, then wired mics will be ideal.

      Wireless mics are often much bigger and heavier than their wired counterparts as well. Hence, you might want to take that into consideration when choosing which type of microphone to use. They also seem less durable (in my experience) as they contain extra transmitting circuitry, and extra features on the mic itself.

      Thanks for your comment, and do drop by again for more updates!

  2. It’s amazing to see just how much technical knowledge has to go into making a quality recording! You have picked a great niche and obviously have a lot of knowledge about the subject of audio devices.

    I thought the site was laid out very nicely, and the graphics within the post helped me to better understand the functionality of a microphone preamplifier.

    • Hi Alec!

      I am happy to know that you have enjoyed reading this article. Do keep in touch with me if you have any questions!

      Thanks a bunch!

  3. hi farhan. great arcticle! i actually produce music on ableton live myself and it was so painful to teach myself the basics of sound engineering, EQ, compression, sidechaining, all of those things! i remember when i first bought my first synth, massive OSC i was staring at all of the circuitry completely dumbfounded, i wish i had a blog like this to educate me faster! one thing that might help is for people like me who are slightly sleep deprived, very simple terminology that is easy to follow would help to give me the initial idea, and then digging into the technical terms 😛

    do u have a soundcloud? they are saying my comment is not unique and i’m thinking wtf? this is 100% unique

    • Hey Ben!

      It brings me great joy to hear that my website is providing quality information to people who needs them. That is the whole point of this site, which is to educate people in different aspects of audio engineering, in a more laid-back and casual fashion.

      Unfortunately, many technical terms that are used in my articles have to remain, as this is central in aiming to produce more accurate content. In order to balance between readability and technicality in my articles, I cannot afford to explain every single technical term. My aim is for people to have a strong general understanding of various topics.

      I used to have a soundcloud account, however that was sometime ago. I will be sure to update the website if I have any tracks to share.

      Thanks a lot for your thoughts, and feel free to come back anytime!

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