What Is The Difference Between An Audio Interface And A Soundcard?


Today I am attempting to answer another question which I frequently get asked via email. Frequent readers of the blog will know that I say a key part of any home studio is a good audio interface. But is this the same as an external soundcard?

Yes, an audio interface IS an external soundcard that is specifically designed for audio production. But it is also much more besides, with specialised drivers, inputs and outputs, making recording music a much better experience.

In this article I will explain what a soundcard is, where you are likely to find one and why I think an audio interface is worth the investment.

All computers and laptops will have a soundcard built in

Soundcards have been appearing in computers and laptops since the late 1970s with the Apple II computer. But it wasn’t until the late 1980s that the majority of machines began to have then pre-built in.

It is an internal expansion card with various inputs and outputs to allow you to get sound into or out of the computer.

Why are they required?

Although they may eventually take over the world, for the time being a computer is not able to understand an audio signal. It is the equivalent of a foreign language to it. Computers still like to think in digital format, basically a series of 1s and 0s.

A sound card helps by acting as this translator. It uses a digital to analog converter which converts the analog audio signal coming in from perhaps a microphone into a digital signal that the computer can interpret. It also does the same in the other direction, when you play a song on Spotify the soundcard converts the digital signals into audio signals that allows you to plug headphones or speakers in and listen.

The earliest soundcards were only really capable of producing a series of beeps and boops. But they have come a long way since, now able to produce high quality audio in stereo (sending different audio to left and right speakers).

An audio interface IS an external soundcard

The best way to think of a professional audio interfaces, such as my Focusrite interface shown above, are as soundcards with added extras.

This is where confusion can often creep in and why I often get asked what the difference is.

So you don’t need to buy an audio interface AND and external soundcard because they are the same thing.

These days most connect to a computer via a USB connection. Although it is worth double-checking this as some use other connection types such as thunderbolt.

So why do I need an external soundcard then?

You may well also be asking; “If all laptops and computers have a built-in soundcard, why do you need to buy an external soundcard or audio interface?”

Another great question.

The reason for this is a question of quality and also all those extra features I mentioned.

Let me quickly break down all the added extras that you get when you choose to use an external soundcard. 

A Higher Quality Digital to Audio Converter

An external soundcard or audio interface is built for the job of audio production. The soundcard that comes built into your computer or laptop just needs to be ‘functional’.

Computers or laptops aren’t designed with professional musicians in mind, they just need to do a basic job. They might be used by people to watch Youtube videos or play games. They do all these things just fine but are not specialised and you therefore don’t get the highest quality.

An external soundcard has enhanced digital to audio conversion capabilities. I.e it does the job much better.

One of the biggest factors is the speed at which the signal is converted.

‘Latency’ is the term used to describe a gap between when a sound is played and when it is heard. So a slow digital to analogy conversion will cause higher latency.

Latency is the enemy of musicians. Even a small amount can make recording virtually impossible. Imagine recording along to a backing track, thinking you are perfectly in time to realise it has been recorded ever so slightly out of time due to slow conversion by the soundcard. Frustrating is an understatement!

Higher Sampling Rate and Bit Depth

This may sound like it is getting a bit technical now, but bear with me, this is important.

Bit depth describes the detail of the digital signal processed. So the more ‘bits’ the higher the bit depth and therefore the more detail within the sound and the better the quality of your recording.

The sample rate is the amount of data your gear captures in a single moment. The higher the sampling rate the more information is captured and the better the quality once more.

Dedicated drivers

To improve performance even more. An audio interface will have dedicated drivers.

In simple terms a driver is a group of files that allow hardware devices to communicate with a computer operating system.

Although you can download special drivers for your computer such as ASIO. Which I wrote an entire article about if you are interested. The drivers in audio interfaces are of the highest quality following professional sound engineering protocols.

Various input types

Perhaps one of the more immediately obvious differences and therefore benefits of an audio interface over a built in sound card are the additional specialised inputs you have.

A built in soundcard will usually have a few very simple inputs and outputs (connections to allow you to get the sound in and out of the computer). These most likely include will most likely be a 3.5mm headphone output, one I’m sure you will be familiar with as it has been present on most phones and MP3 players for decades now.

They may also include a microphone input but it will be a small 3.5mm input. Fine for connecting a basic computer microphone but not great if you want to connect a professional XLR microphone.

An audio interface will have one or probably more input channels which can take 1/4 inch jack type connections (guitar cable) and XLR type connections (microphone cable).

Various output types and direct monitoring

The line outputs on an audio interface will usually have a variety of connection types. As you can see on my Focusrite interface below there are outputs for both balanced and unbalanced type connections.

This allows you to directly monitor sound you are inputting from a microphone or other instrument. As well as allowing you to output sounds from the computer in high quality to studio monitor speakers.

Built in pre amp

A pre-amp boosts a low level audio signal such as that from a microphone or an electric guitar. This makes the signal strong enough for output or processing.

It used to be the case that you would need a stand alone pre-amp. But now most audio interfaces have one built in. this helps give you not just a louder signal but a clearer signal.  

For the full difference between a pre amp and an audio interface check out this article.

Built-in phantom power

Phantom power may sound like some strange mythical force. But it is actual essential to make many microphones work.

Phantom power is a direct current (DC current) sent down a microphone cable to make active circuitry in some musical equipment work.

A condenser microphone needs this as it contains a diaphragm which needs an electrical charge adding to it to start it moving.

Many audio interfaces have a phantom power button meaning you can use condenser microphones. Something you won’t be able to do with a computer’s internal soundcard.

Other useful lights, buttons and knobs

Finally an audio interface will have a range of lights, buttons and knobs to assist you in the music making process.

Particularly helpful are ‘meter’ lights. These light up green when a signal is registered. So even if you don’t have your headphones in or your speakers on you can sing into a microphone or play your guitar and if the light turns green you know the interface has registered a signal. The meter lights will also turn red to tell you that clipping (distortion) is occurring, I,e you are playing too loudly.

Other knobs allow you to adjust input gain and speaker volumes easily. All things that are not easy to do when using a built-in computer soundcard.

Recommended Audio Interface/ External Soundcard

I love the Focusrite Scarlett series of interfaces.

As you will have seen from the pictures in this article, I own one myself and have done for years.

They are reasonably priced, sturdy, packed with features and look awesome!

Focusrite do a number of different models at different price points depending on what you need. A higher price will get you more inputs and other features. If you are just recording music on your own you will probably never need more than 2 inputs at any one time and so the 2i2 shown below should do just fine.

Rob Wreglesworth

Rob has come to terms with the fact he will probably never be a famous rock star....but that hasn't stopped him from writing and recording music in his home studio. Rob has over 15 years experience of recording music at home.

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