Do Condenser Microphones Need A Preamp? - Easy Explaination

When I first started recording, one of the first things I wanted to do was record some simple acoustic guitar and vocals. I only owned an acoustic guitar at the time, and all that was missing to begin recording was a microphone. So I did some research and decided to purchase my first condenser mic. I knew that condenser mics needed phantom power, but what about the preamp?

So, do condenser microphones need a preamp? 

A mic preamp is needed for condenser microphones because it provides 48v phantom power for the microphone to work. Moreover, the audio signal produced by the microphones is weak, so they need a preamp to amplify the signal so that it can be transmitted to mixing consoles and other recording devices.

In this article, I will explain in detail why you need a preamp for your condenser microphone, as well as give you a good idea of what a microphone preamp does, how much it costs, how to use it with your audio interface, and much more.

Do I Need A Preamp For My Condenser Mic

Despite the fact that mic preamps are crucial instruments in any recording studio, not everyone who has a home recording studio – or is thinking about setting one up – understands its importance or appreciates the value of a decent mic preamp.

What Is A Mic Preamp?

A microphone preamplifier is an active electronic device that is designed primarily to supply gain to a mic signal in order to output the signal at line level.

Audio signals produced by the microphone (“mic level)” are usually too weak and can not be transmitted and processed by devices such as the mixing consoles or DAWs. 

A mic preamp amplifies these microphone signals from “mic level” to “line level”.

Once the audio signals are amplified to “line level”, they can be used with other audio equipment such as mixing consoles, recording devices, or digital audio workstations.

Mic preamps aren’t necessarily “100% transparent” – they can change the tonal characteristics of microphones, and, therefore, are an important part of the recording process.

The quality of the mic preamp is of utmost importance. You will notice that most budget preamps inherently introduce at least some degree of hiss and background noise to your signal. A good mic preamp will surprise you with just how much quieter your signal can be.

Poorly designed and cheaply made preamps will deliver thin-sounding, poor-quality audio with high noise levels.

Why Do Condenser Microphones Need A Preamp

As I mentioned at the beginning of this article, condenser microphones need a preamp for two main reasons:

  • Condenser mics need a preamp for 48v phantom power.
  • Mic preamp amplifies the audio signal to “line level”.

Now let’s discuss these two reasons in greater detail.

Condenser Mics Need Preamp For Phantom Power

Condenser mics need a separate power source to work and record.

A condenser microphone contains a diaphragm, which is usually made of very thin metal, and another piece of metal called a backplate. 

Electricity is applied to both of these creating a static charge between them. The amount of electricity required ranges from between 9 and 48 volts.

This tiny bit of electricity needed to make the diaphragm move in a condenser mic is called the “Phantom Power”. This power usually comes from your audio interface or the mic preamp

So, it’s the preamp that provides the charge for phantom power, causing the condenser microphone to record sounds.

Preamps Amplify Condenser Mic Signals To “Line Level”

A mic preamp not just provides phantom power to a condenser mic to record, it also brings the sound levels of the condenser microphone from “mic level” up to the “line level” so that the signals can be processed by other devices.

A microphone preamp takes a microphone audio signal at its input, applies an appropriate amount of gain (which is typically adjustable), and outputs a line-level signal.

The audio signals that are produced by condenser mics or any other mics are too weak to be transmitted and processed by other recording devices such as mixing consoles.

Microphones produce audio signals at a “mic level” that greatly ranges from -60 dBV and -20 dBV.

A mic preamp takes these low-level signals and amplifies them to a “line level” of +4dBu (1.78 dBV).

This “line level” is the professional standard for recording/mixing audio devices such as mixing consoles and digital audio workstations.

As I mentioned before, a mic preamp applies “GAIN” to the condenser mic signal to bring it up to the “line level”.

Gain works by adding energy to the signal. This energy is converted from an external power source of some sort (whether that’s an AC wall plug, phantom power, or batteries).

Gain boosts signal strength from mic level to line level so the condenser microphone signal is compatible with professional recording devices. Mic preamps control gain and are typically the first circuits a signal passes through after the condenser mic output.

Is My Audio Interface A Preamp?

 Most Audio Interfaces, even the inexpensive ones, come built-in with mic preamps. These preamps that come with audio interfaces sound amazing and should be more than enough for 99% of the users. Generally speaking, any interface with XLR mic inputs will already be a microphone preamplifier as well.

If you’re just beginning to record, audio interfaces will help bring the recorded sound from the microphone to the computer or amplifiers.

If you have a condenser microphone, it’s essential to buy an interface with phantom power capabilities and preamps. 

My favorite is the Focusrite Scarlett 2i2 USB Audio Interface, as I have been using it for some time now and moreover, it contains award-winning preamps.  It’s pretty simple with limited functionality but is more than enough for many project studios.

I would also like to inform you that the most expensive audio interfaces by top brands will feature much better outstanding preamps. The Focusrite Scarlett 18i20 3rd Gen USB Audio Interface is a perfect example of a top-of-the-range audio interface with great preamps.

In cases like these, your audio interface will be more than enough, pretty much blurring the line between “audio interface” and “preamp”.

Do I Need An External Preamp For My Condenser Mic

All condenser microphones have a preamp; this includes head-worn condenser mics and lavalier condenser mics.  With handheld condenser microphones and studio condenser microphones, the preamp is not as obvious, because the preamp circuity is contained within the mic handle/housing.

Although condenser mics come with built-in preamps, these are generally weak sound boosters and need an extra push to make it up to the average line level. 

If you’re only starting out, forget about an external preamp. Instead, get a slightly more expensive audio interface with decent built-in preamps (Any one of the above that I mentioned above). 

But If you already have an audio interface or don’t want to buy one, you can go ahead and purchase an external mic preamp.

If you decide to buy an external mic preamp then I highly recommend the MXL Mic Mate. It’s perfect for on-the-fly recordings, podcasting, streaming, field recordings, and more. It converts any existing condenser microphone to a USB. Includes studio-quality USB microphone preamp, fully balanced low-noise analog front end, and 3-position analog gain switch, and it also supplies 48V phantom power.

How To Connect a Preamp To an Audio Interface

An audio interface will be an integral part of your recording setup. If you decide to upgrade to an external preamp, you’ll still need to use your interface.

Here’s how you can connect an external mic preamp to your audio interface:

  1. Plug your microphone (using an XLR cable) into the external preamp’s mic input.
  2. Connect a cable either an XLR or TRS cable ( balanced 1/4 inch cable) to the output of the preamp
  3. Your audio interface may have some microphone XLR inputs as well as some 1/4 inch TRS inputs for line-level sources. Plug your preamp’s output into a line-level input.

Make sure that you never plug your preamp output into an audio interface mic input. This would mean that you are inputting a line-level signal from your preamp straight to the interface’s own mic preamp. Doing so will surely cause unwanted distortion of the signal, as you’re basically running the signal through two preamps.

Conclusion

A preamp is necessary to amplify the audio signal of a condenser mic up to line level and to provide the phantom power required for the mic to work. If you are just starting out, then forget about external preamps, you should rather purchase an interface or mixing board that includes a few high-quality preamps, like Focusrite Scarlett 18i20 (3rd Gen) USB Audio Interface.

Frequently Asked Questions

Do I Need A Mic Preamp If I Have An Audio Interface?

Most audio interfaces, even the inexpensive ones have built-in preamps which are capable of producing good transparent sound quality. However, getting an external preamp will help you achieve an overall better signal and, therefore, a better sound as well.

Does A Preamp Improve Sound Quality?

A dedicated preamp imparts a great texture to the sound. A good mic preamp will deliver a cleaner, more accurate signal, with higher gain, lower noise, less distortion, and more headroom.

Do I Need A Mic Preamp If I Have A Mixer?

Most mixers nowadays come with built-in mic preamps, so you don’t need to buy a separate external preamp.

However, a dedicated external preamp can improve the sound quality if the preamp in your mixer isn’t up to the job.

Do Dynamic Microphones Need a Preamp?

Dynamic microphones need a preamp to boost their signal strength from mic level to line level. A dedicated standalone preamp is not needed as most audio devices such as mixing consoles, DAWs, audio interfaces already come with one built into them.

Written by:
Amit Gupta
Amit Gupta

Hi, my name is Amit Gupta, and I am the owner and contributor at Radaudio. My passions include guitar, bass, and piano, as well as a range of classical instruments that I have been playing since school.

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