The importance of a sound card in the sound recording process cannot be overstated. A sound card, also known as an audio interface, is a kind of bridge between the composer and their work in the form it will take during the recording process.
Without a doubt, the more reliable this musical bridge is, the more likely you are to achieve the desired result faster — a great-sounding, high-quality track, podcast or any other audio recording.
Sound cards come in multimedia and gaming varieties, as well as built-in and compact models. In this article, we will only discuss full-size external audio interfaces designed for recording in a home or professional studio.
Why do you need an audio interface?
At the highest level, an audio interface is needed to connect a musical instrument or microphone to a computer and record them in special DAW (Digital Audio Workstation) software, as well as to work with music plugins.
An audio interface converts the analogue signal received, for example, from an electric guitar or microphone, into a digital signal of the highest quality, in a sense replacing analogue amplification methods such as tube and transistor amplifiers.
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Beginners may ask: ‘Can I connect a microphone directly to my laptop and record my voice or instrument?’ Yes, you can do this, for example, with a USB microphone, but the sound card built into a laptop is not designed to work with high-resolution audio. With a built-in or even multimedia (consumer) sound card, you can achieve acceptable sound quality, but it will not be professional, and this will be noticeable. In addition, you will not be able to monitor the recorded signal properly.
And here is the second most important role of an audio interface — monitoring sound using studio monitors or headphones. During the recording process, it is very important to hear the nuances of what you are recording in order to control the quality of the performance, voice intonation, and other parameters. In this case, a characteristic such as sound delay becomes very important. With direct monitoring through a sound card, it tends to be zero, but when monitoring sound processed by a DAW, there is a slight delay, and the higher the quality of the audio interface, the shorter the delay will be.
Important characteristics of audio interfaces
A delay of more than 20 ms is a serious obstacle to high-quality recording and live performance; 10–20 ms is acceptable for some tasks; less than 10 ms is inaudible to most people. It is also important that the audio interface has a direct monitoring function, i.e. without any delay at all.
Bit depth and sampling frequency directly affect signal quality. A value of 24 bits at 96 kHz is optimal for professional sound work.
Number of inputs — for connecting multiple instruments simultaneously. For example, electric guitars via instrumental TRS, microphones with phantom power via XLR, MIDI controllers or synthesizers via MIDI input. Modern audio interfaces can have from two to several dozen inputs, and there are also options with an expanded number of channels.
The number of outputs for studio monitors and headphones, TRS or RCA, can be two or more.
Connection to a computer via USB-C (the most common option), Thunderbolt, FireWire, USB-A.
The quality of the preamplifiers is the most important characteristic for signal volume and clarity.
Additional features include built-in DSP processors for real-time sound processing without delay.