Everything You Need to Know About Preamps

 A voice over artist doesn’t necessarily have to be a tech wizard to practice their craft, but understanding their equipment and how it works can help make them better at what they do. 

That’s why it’s essential to learn about everything from microphones to audio signals and processing when designing a home recording studio. 

This blog is a double-down on preamps (preamplifiers) and interfaces. 

What’s a Preamp?

Voice Over Home Studio Assembly

A preamp is a piece of processing equipment commonly used in recording audio. It allows an engineer or voice talent to boost an audio signal by increasing the gain. Typically the signal produced by microphones is relatively low—this is called ‘mic level’—and it needs a boost to ‘line level’ before it can be processed. That’s the work of a preamp. 

It’s also part of the chain of equipment that gets the sounds you record via microphone into a computer, which requires converting analog signals into digital recording. Every voice actor needs the ability to pre-amplify their recording before the analog signal becomes a digital one. When you’re just starting, you might be able to use a USB microphone with a built-in preamp, but most freelance talent quickly outgrow a simple USB mic. 

Now that we understand the basic concept of a preamp, let’s look at how it fits into the production process. While it’s really important, it’s usually only half of the equation for getting the most out of your voice. 

What is an Interface?

An audio interface is a system that gets the microphone’s signal onto a computer. It increases and improves the sonic capabilities of a computer when converting the analog signal from your microphone into a digital format. 

The quality of the interface affects the quality of your recording. Less expensive interfaces tend to lose detail and definition in the process and can often mask or dampen the voice qualities that producers want from your vocal performance. 

Interfaces always convert analog signals to digital ones, but most also boost the level of the microphone’s signal through a built-in preamp. In other cases (like high end professional studios), the converter and the preamp are separate pieces of hardware.

Choosing the Right Interface and Preamp

Since the audio interface is an essential part of any recording, it’s critical to understand your options before buying one. The combination of microphone, preamp, and digital converter can have a tremendous amount of influence on the quality of voice recordings you produce. 

Here are three main criteria you should look at when considering an audio interface or a preamp:


First, make sure your preamp is compatible with your other equipment. For example, does it use USB, USB-C, a Lightning Connector, or FireWire? Do you need adapters to make connections? If you do, will they degrade the overall quality of the signal, or add more self noise to the recording? Check all the connections for compatibility.

Quality and Features 

Many studios and voice actors use a version of a condenser microphone, making a preamplifier necessary to boost the output. The preamp helps to pump up the gain. 

High-quality preamps preserve the subtleties of the signal, effectively increasing the power without sacrificing the overall quality. These preamps are usually external, standalone pieces of equipment purchased separately from other components (not the combo preamp/interface boxes that are still commonly used).

Equally useful to voice actors—and usually much less expensive—preamplifiers are often bundled with the digital converter into one piece of hardware: the interface. This is convenient and affordable, but it tends to degrade the overall signal before it reaches your computer. 


Today’s mics almost all have great input and are usually adept at catching most of the subtleties in a voice actor’s performance. But the output is usually a very quiet signal, even when set up properly. To get that signal up to the right level for additional processing or amplification, it needs to run through a preamp for the best results. 

There are quite a few mics that offer a USB-type connection. If you’ve used one, you may be wondering why they don’t have a preamp or a digital converter…but they do. Instead of an external interface, it’s built into the mic. The signal coming through the wire is already digital and needs no more boosting or converting. 

That’s different from higher-grade, professional XLR style microphones. These mics are much better than a USB mic in terms of the sound quality they capture, but they will need an external interface to get their output onto your computer. 

Microphone Special Note

All condenser mics require phantom power. Phantom power is an electrical current sent through a microphone cable to power a microphone or another device. If you have a mic that uses phantom power, be sure your audio interface supports that feature or your mic won’t be energized. 

Audio Interfaces For Voice Over

Preamps and Audio Interfaces: Choices

It might be easier to think about preamps and audio interfaces separately. At their most elementary, a preamp boosts the signal. An interface usually has a preamp built-in, so you can both increase the signal’s strength and convert it to a digital format for your computer. 

The giveaway that an interface has a preamp built into is a set of controls that say ‘level’ or ‘gain.’

Here are some specific pieces of hardware to check out when shopping for an interface:

Mbox Pro and Mbox Mini

Mbox offers a professional-level audio interface in either a Pro or Mini version. Each unit allows you to capture sounds exceedingly well and converts them into recordings of the highest quality. The larger Mbox Pro has eight inputs and eight outputs, including two dedicated headphone jacks. It connects to your computer using a FireWire cable. 

The Mbox Mini pares things down for portability and has only two inputs, two outputs, and a single headphone jack. It connects to your computer via a standard USB cable. Both versions come with Pro Tools recording software, which is pretty much the voice actor’s industry’s standard.

The Pro is $600+ while the Mini will run you $300.

Griffin iMic — USB Audio Interface

The iMic universal audio adapter is a simple external sound card that offers a stereo input and output to your Mac or PC through its USB port. iMic’s audio is typically better than all but the most expensive desktop’s built-in soundcard due to its use of a USB for transferring the audio signal. This is a simple, portable interface that offers a single ⅛” input and output for connecting devices. 

The Apogee One and Duet

The Apogee Duet is an outgoing audio interface with two inputs, four outputs, and a USB interface. It has a two-channel audio interface with a 48-volt phantom supply for both channels. Its preamps and digital converter are exceedingly accurate. 

It’s been replaced by the Duet 3, which offers similar connectivity, but even better processing. If you don’t need as many connections, consider the less expensive Apogee One with a built-in mic, two inputs, and two output channels. However, it doesn’t have a 48+ (48-volt phantom power) connection.

The Apogee One will cost you $350, while the Apogee Duet (refurbished) will run you $550 and the Apogee Duet 3 clocks in at $650.

Note that if you’re an Apple user, Apogee products typically integrate seamlessly and require less software configuration with GarageBand and Apple Logic Studio.

Focusrite Red

The Red range of audio interfaces offers an impressive array of audio processing controls. This suite of hardware and plug-in software allows voice artists and professional studios alike the options they need to extract the sound they want from their vocal performance. 

Check out their Focusrite Scarlett 2i2, with USB connectivity and two input and output channels, with a digital converter and preamp in one. 

The Focusrite Scarlett 2i2 costs $150.

Apollo Twin

The Apollo Twin may just be the new gold standard in desktop audio processing. It has all the features and connectivity you can dream of, including multiple channels, a preamp, a digital converter, +48V power, and more. It’s a little hard to find, though, so you may need to buy one second-hand. 

SSL2 Audio Interface

The SSL2 Interface uses a USB-C connection and offers two input and four output channels. Both inputs have 48+ power, and there are two dedicated headphone outputs. Tune the gain on each channel independently to mix vocals and other sounds in the studio.

An SSL2 Interface is about $350. 

Other Interface and Hardware Options

You should also look into a few other interfaces and hardware options when designing and assembling your voice over home studio.

  • M-Audio Interfaces
  • Roland’s Edirol AudioCapture
  • Lexicon Lambda

Preamps Bottom Line

Every good home studio needs a preamp. It’s up to you to find one that works best for your voice talent!

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