How to choose the right audio interface

The audio interface is essential in every home studio setup. But how to choose the right one, considering all your needs? And what do all those technical terms like sample rate, Hi-Z and 48V mean?

How to choose the right audio interface

The audio interface is essential in every home studio setup. But how to choose the right one, considering all your needs? And what do all those technical terms like sample rate, Hi-Z, and 48V mean?

Contents

What is an audio interface?

The audio interface plays a central role in any home studio. It connects devices like your computer, studio monitors, headphones, microphones, and instruments such as a guitar, synthesizer, or drum machine.

The audio interface converts analog signals into digital signals and vice versa. In addition, it ensures that you can easily play software instruments and effects with a MIDI keyboard. All without those annoying playback delays (latency).

Most modern audio interfaces are connected to a PC or Mac via USB. Some are connected via thunderbolt or firewire.

How to choose the right audio interface - the front of an audio interface
Audio interface with 2 combined microphone/instrument inputs on the front, both with volume and signal controls.
How to choose the right audio interface - the back of an audio interface
The connections for studio monitors, headphones, and MIDI cables are at the back.

Is an audio interface the same as a sound card?

Yes, it does the same as a sound card. It converts analog signals to digital signals and back again. The audio interface can be seen as an external sound card. The advantage is that you don’t need to open the computer case for installation. And it’s much easier to plug in your microphones and instruments for spontaneous recordings. For laptop users, it’s the only option for high-quality audio recordings.

Why do you need an audio interface?

The audio interface is very easy to use. You connect instruments and microphones without any effort. So you can focus on making music. In addition, the audio interface allows your DAW software to play audio without any delay (latency). That’s great while mixing and mastering music too.

Some audio interfaces have MIDI inputs and outputs for hardware synthesizers or drum machines. For example, you can connect the instruments with a MIDI cable and play them back with your DAW software.

How to choose the right audio interface?

Before buying an audio interface, you need to consider what connection you need (USB, Thunderbolt, or Firewire). In most cases, USB will be the way to go. Then think about how many instruments and microphones need to connect at the same time. And which outputs you need, for example for studio monitors and headphones.

Summary

  • USB, Thunderbolt or Firewire?
  • How many mic/instrument inputs?
  • Hi-Z support for guitar?
  • 48V phantom power for vocals (condenser microphone)?
  • Outputs?
  • MIDI output/input?

For most beginners, an audio interface with 2 microphone-instrument inputs will probably be enough.

Example 1: singer-songwriter

A singer-songwriter needs at least 1 microphone input, 1 line input for instruments, and direct monitoring.

Are you a singer-songwriter? Then you probably want an audio interface with at least 1 microphone input with 48V phantom power and 1 line input for instruments such as a keyboard or electric guitar. This way, you can immediately make live recordings of songs that come to mind.

Direct Monitor will also come in handy. It allows you to listen to your vocals directly via the headphones while recording. You don’t have any annoying delays during playback.

Example 2: the synthesizer enthusiast

Do you want to play older hardware synthesizers via MIDI and record them within your DAW software? Then choose an audio interface with MIDI input/output and at least one instrument input for recording.

Modern synthesizers, drum machines, and MIDI controllers often have a USB connection for MIDI playback. Then your audio interface doesn’t need to have MIDI connections. One or two instrument inputs are all you need for mono or stereo recordings.

When do you need more than 2 microphone instrument inputs?

Audio interface with more than 2 inputs
The Zoom UAC-8 has 8 microphone-instrument inputs, enough for recording a band!

Do you have several instruments in your studio, like synths, microphones, guitars, and drum machines? Then more than 2 instrument inputs could be very useful. This way you can connect all instruments to the audio interface at once and record them spontaneously after switching on. This way you can make and record music without much extra work.

An audio interface with more than 2 microphone-instrument inputs is also useful if you want to record a live band on different tracks in your DAW software. It makes it easier to mix the music later.

48V phantom power for condenser microphone

When recording vocals or an acoustic guitar, you get the most beautiful recordings with a condenser microphone. You connect them to an XLR connection with 48V phantom power. The audio interface has a dedicated switch or button for the phantom power.

Audio interface with 48V phantom power
48V button for microphone phantom power.

Hi-Z for electric guitar and bass

You can connect an electric guitar or bass directly to an audio interface with Hi-Z support. By pressing the Hi-Z button, the (weak) signal of your electric guitar is amplified for recording into your DAW software. You don’t need a DI box.

Tip for electric guitarists: Archetype Plini

There are great plug-ins available which emulate the sound of famous amps like the classic Marshall. I myself use the impressive Archetype Plini plugin by Neural DSP. It takes quite a bit of computing power, but it sounds fantastic. Highly recommended for electric guitarists. You no longer need a bulky amplifier and effects box in your home studio!

There are great plug-ins available that emulate the sound of famous amps like the classic Marshall. I use the impressive Archetype Plini plugin by Neural DSP. It takes quite a bit of computing power, but it sounds fantastic. Highly recommended for electric guitarists. You no longer need a bulky amplifier and effects box in your home studio!

Line outputs for studio monitors

Studio monitors are connected to the line outputs on the back of the audio interface. More expensive audio interfaces are equipped with balanced line outputs for a better sound signal.

The longer the cable, the weaker the signal. Keep this in mind when buying new cables for your studio monitors. With new cables, you should also take a look at the connections of your studio monitors and audio interface.

Do I need an audio interface for my USB microphone?

No, you don’t need an audio interface for a USB microphone. It already has a built-in audio interface. You can immediately start recording after connecting the USB microphone to your computer.

You can easily connect the RØDE NT-USB condenser microphone via USB.

Technical terms

Sample rate

The sample rate is the number of times per second at which the sound is digitally sampled. It’s an indication of the quality of your recordings. The sample rate is indicated in kilohertz (kHz). At a sample rate of 44.1 kHz, the analog signal is sampled 44,100 times per second.

The sample rate must be at least twice as high as the highest sound frequency you want to capture. The human ear can perceive frequencies from 20 Hz to 20 kHz. In that case, you need a minimum sample rate of 40 kHz. With a sample rate of 44.1 kHz (CD quality), you have enough buffer to record music without any problems.

More expensive audio interfaces can even make recordings at 96 or 192 kHz. These higher sample rates make pitch shifting or time-stretching more easily after recording. But the audio files become a lot larger too.

Sampling an analog signal - sample rates explained
Sampling an analog signal at discrete times. Source: Wikipedia.

Bit depth: dynamic range

The sample rate always shows the bit depth too (in number of bits). For example, a CD-quality recording is 44.1 kHz/16 bits. The bit depth represents the dynamic range of the recording.

The higher the dynamic range, the less you will be bothered by noise in your recordings. The dynamic range of 16-bit is 96 dB. The studio world often works with 24 bits, which gives a dynamic range of no less than 144 dB.

I usually make recordings in 44.1 kHz/24-bit quality. This is even higher than CD quality (44.1 kHz/16 bits). This way, I always get good recordings without any noise.

Latency

This is the (noticeable) delay between the sound being played and the playback on your headphones or studio monitors. Latency can be annoying with vocal recordings because you cannot hear yourself immediately through the speakers.

Latency can also be annoying when playing a software synthesizer with a MIDI keyboard. You will not immediately hear a tone when you press the keys, it always plays back with a delay.

Audio interfaces address this problem by drastically reducing latency, including support for Steinberg ASIO. You can find the latency in milliseconds (ms) in the audio settings of your DAW software.

Microphone Preamp

A microphone preamp boosts the weak microphone signal. It allows you to make a recording into the DAW software of your computer.

48V phantom power

Certain types of microphones require additional power to function properly. For example a condenser microphone for vocals. You can turn on the 48V phantom power with a button or switch.

Direct Monitor

Direct Monitor is a useful feature when recording vocals and instruments. By enabling Direct Monitor, you listen to your vocals or instrument directly via the headphones without annoying delay.

MIDI IN/OUT

The MIDI IN/OUT allows you to connect a synthesizer or MIDI controller via the good old MIDI cable. New synths and controllers are often equipped with USB. In this case, you don’t need this option.

MIDI cable
A MIDI cable lets you connect (older) synths, keyboards, and MIDI controllers to your audio interface

Unbalanced/ Balanced

The longer the cable, the weaker the sound signal. Longer cables can cause noise or hum in weak signals. You can avoid this by using a balanced cable. The connected equipment must be suitable for this technique. For example, both your audio interface and studio monitors or microphone.

Cheaper audio interfaces often have unbalanced connections for economic reasons. However, you can usually make recordings without any problems.

Drivers

The driver software ensures that the audio interface works with low latency. You can usually download the latest drivers from the manufacturer’s website. During installation, it’s best to check whether new drivers are available for your audio interface. This way you can be sure that your audio interface works properly.

Conclusion

After you know your needs you can go shopping for a nice audio interface. In general, the more microphone/instrument inputs, the more expensive the audio interface.

Most of us will have enough with only 1 microphone and 1 instrument input. There are audio interfaces for less than 100 euro that meet these requirements. Read The best 8 budget audio interfaces under €200 to learn more!

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