What Is A Preamplifier & What Is It Used For?

Are you looking for ways to improve the sound? We are sure that it is. If you are starting in recording, the preamplifier is an indispensable part of recording equipment. The purpose of a preamplifier, as the name suggests, is to amplify low-level signals down to line level, i.e., the standard operating level of your audio equipment.

If you have an AV receiver with a built-in preamp, you might think you don’t need an external preamp. However, many sounding enthusiasts and professionals prefer a separate setup with a preamp and amplifier because it achieves a full sound with minimal distortion. And this gets a  clean sound.

What is a preamplifier?

A  preamplifier is a device that connects to the output of the microphone. Its function is to capture the signal from the microphone and emit an amplified version of those signals with as little external noise as possible.

If you connect the microphone directly to an amplifier or any other device, you introduce too much noise into the audio. Therefore, it will sound less clear. If you’ve been recording for a while, you’ve already used some preamp to boost your microphone signal.

One thing you should know is that preamplifier can be standalone devices. But they can also be integrated into other audio equipment you already have, such as your audio interface, PA system, or mixer.

Its duties?

As you have seen, the preamp is a complex element that does much for the sound. But what exactly are the functions of this device?

As its name suggests, the preamplifier is the first stop for the audio signal before it goes through the preamplifier and reaches the speakers. It makes a weak sound signal loud enough for further processing,  avoiding noise and providing a cleaner output.


The minimum requirement is the microphone input. For stereo recordings, you need at least two. Microphone inputs come with an XLR connector; TRS connectors are not acceptable for microphone inputs. Audio interfaces and some external head amps also have line inputs. These can be balanced or unbalanced. Balanced connections are more immune to electromagnetic interference. Line inputs use TRS or XLR connectors, often found on high-end equipment.

Phantom power

Voice recording microphones contain internal electronic components that require an external power supply. Dynamic microphones don’t need that external power supply. The solution to this dilemma is  Phantom Power. This feature allows microphones to be powered for voice recording from the microphone input without needing an additional cable. That’s why it’s called phantom power because it’s invisible.

Gain control

This is the main function for which an external device of this type is chosen. The quality of a mic preamp becomes more apparent at higher gain settings. Above about 50dB of gain, cheap preamps sound increasingly flat and lifeless. A top-notch preamp retains its superior sound quality even at its highest settings. You should invest in a high-quality mic preamp to get the optimal sound from dynamic mics, especially ribbon mics.

Low cut filter

Many preamps come with a low-cut switch. They have filters that attenuate low frequencies and let higher frequencies through. Low-frequency cutting is a way to eliminate rumble and other unwanted noise within a piece of music. A low cut (at a higher frequency) can also be used for creative purposes, i.e., to shape the sound.

Reverse polarity

This function inverts the polarity of the signal. This function is useful when recording an instrument with more than one microphone. If, for example, you record a cabinet with two microphones, one above and one below, you have to reverse the polarity on one of the two so that both signals are in phase. Because if you left them out of phase, the two signals from the microphones would partially cancel, resulting in a more refined sound.

Reasons why you should have one

There are several reasons to have a device that amplifies the sound in your recording equipment. Here we give you the main ones:

  1. Better sound quality. This becomes more apparent at higher gain settings. High-quality external preamps are equipped with more sophisticated circuitry that retains full transparency even at their highest gain settings.
  2. More profitAn external preamp can deliver over 70 decibels. Those already integrated into the equipment do not reach more than 60 decibels.
  3. Lower noise: This is another of the main functions of preamps. Those that are built-in as standard have low noise levels. What this device does is filter noise.
  4. They add coloration to the sound that is difficult to achieve without them.
  5. It has other improvements like inverting and controls that change the harmonic distortions.

Choose the best for your sound equipment.

As we have already said, preamplifier is tools that greatly impact audio. They are the first equipment that many pros recommend upgrading in a studio setup.

On the other hand, today’s preamplifier is often built into audio equipment. So the most important thing is knowing if you need a separate preamp. It’s easy to get carried away with extra features, but remember that if you’re using a standalone preamp, you can always add other features to your rig later. Lastly, make sure you know what other equipment you have. Remember that upgrading to a good-quality preamp will ensure you get the most value out of your gear. So do not hesitate to seek advice and invest in this key element.


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