Audio interfaces are one of the most essential pieces of gear for mastering, mixing, and production. They also happen to be one of the most overlooked, as many producers on a budget tend to focus on working with what they already have at their disposal. We occasionally have clients tell us that a mix was done entirely on headphones or monitors, which were plugged directly into their computers soundcard. Of course we often hear stories of famous EDM producers working with nothing but headphones and a laptop, while perhaps travelling between gigs. Tracks like Eric Prydz's "Miami To Atlanta" are often cited as an example of this. However, we always remind clients that while initial ideas might be conceived using nothing but a laptop and headphones, it is likely that these ideas were later taken into a proper studio and mixed down in an acoustically treated environment, with a quality hardware setup including a high-end audio interface, and high-end monitors. In fact if we could pinpoint one type of mix that sounds consistently amateur to us time and again, it is the "headphone" mix. Though surprisingly to some, headphones aren't the real problem here (though they are part of it). The big problem is the low-quality digital-to-analog converters featured in most laptops and integrated soundcards. Without investing in a quality audio interface, it will be hard if not impossible to get a mix right. Our advice to those who can't afford a proper set up, is to pay a professional to both mix and master their tracks after they have put together. Of course we offer these services, but there are plenty of low-cost mixing services out there for you to choose from. That said, we would like to discuss the vital role of the audio interface in audio mastering, mixing and production.
FROM ADC TO DAC AND BACK
Working with audio in a DAW using an integrated soundcard is much like working with cotton stuffed in your ears. It may sound good to you, but keep in mind that you are not actually hearing an accurate playback of the sounds you are creating. To understand this analogy, let's take a moment to explain the process of digital to analog conversion in this context. When you create a loop using a software synthesizer and MIDI in your DAW, you are working entirely within the digital domain. When you play back that loop, your audio interface is taking the series of 1's and 0's which represent your music, and converts them to an analog signal which is then capable of being heard through whatever is plugged into your headphone jack. This process is known as Digital-to-Analog Conversion (DAC). When audio is recorded from external instruments to a track in your DAW, your audio interface is performing the reverse, known as Analog-to-Digital Conversion (ADC). An audio interface accomplishes ADC by measuring the incoming signal at a number of specific intervals and then converting these measurements into a series of numbers that can digitally represent the audio. DAC is essentially the same process ADC but performed in reverse.
The numbers created by the ADC are based on a series of measurements, with the two most significant measurements being time and gain. Time measurements occur when a waveform is sampled a specific number of times every second. The total number of samples that are taken every second are known as the sample rate. Thus the higher the sample rate, the more samples that are taken every second, and the more accurately the audio will be represented digitally. On low-quality audio interfaces such as integrated soundcards, these measurements are not accurate, and so the converter has to guess what information is missing and attempt to fill in the missing information. This sort of guesswork is called aliasing, and what aliasing sounds like upon playback are called artifacts, or tiny distortions in the sound.
In addition to the time measurement performed during ADC, the gain measurements are equally vital to the process. In order to accurately represent a waveform, a converter must measure the dynamic range via the gain levels. Dynamic range is essentially the difference between the loudest and quietest points in a waveform. Much like sample rates, bit rates determine the dynamic range of the waveform. Much like the problems that occur when sample rates are not calculated correctly, similar problems occur when bit rates are incorrect, in that the converter has to guess what the missing information might have been. This is done by rounding up to the last known point of measurement, which results in what is called quantization error, which again creates audible distortion otherwise known as artifacts. These artifacts can sometimes be hard to hear, but as you continue to work with audio within your DAW, the level of distortion will gradually erode the sound quality of your mix and the final product will be an abrasive sound that lacks sonic detail. Keep in mind that these conversion errors occur regardless of whether or not you are recording external instruments, as the conversion from digital to analog is still subject to the same shortcomings of your integrated soundcard.
A soundcard is just an audio interface, and all audio interfaces feature both ADC and DAC capabilities. Integrated soundcards are just extremely cheap audio interfaces, with cheap DACs and ADCs. In fact integrated audio components are usually constructed as cheaply as possible, in order to reduce the cost of manufacturing the laptop or pc which features them. Integrated soundcards is that are supplied as standard in many computers rely on tiny amplifiers limited to just a couple of volts, and if driven hard will cause heavy distortion to the audio signal. This causes the bit rate and sample rate to be incorrectly converted. Integrated soundcards also suffer from electrostatic interference generated by the motherboard, which will introduce noise, limit dynamic range and as a result will suffocate the higher frequencies of your audio. That said, integrated soundcards will reproduce audio incorrectly, causing your mix to lack sonic detail (to put it gently). This lack of clarity will then result in the producer over processing the mix and lead to a lifeless final product.
By relying on integrated laptop or desktop soundcards, it will be nearly impossible to get a mix sounding right. If you are serious about your production and plan to produce electronic dance music of high quality, you should either look into purchasing a professional audio interface, or outsource your mixdowns to a professional engineer with high quality equipment. Even high-quality acoustic environments and high-end monitors will be limited to the capabilities of your audio interface. In light of this, producers forgo these recommendations at their own peril.