Preamps and audio interfaces are two highly useful components in any recording setup. These devices often get grouped, and this can cause some confusion over their purposes, functions, and capabilities.
Although there are indeed similarities shared between preamps and audio interfaces, these two devices perform completely different roles in a recording environment.
In this guide, I’ll explain the differences between audio interfaces and preamps. I’ll get into the details of each device, and how to use them to enhance your recording process.
Table of Contents
What is a Preamp?
Preamps are not essential components for recording audio, but they certainly offer countless benefits that make them a wise addition to your studio. The fundamental purpose of these devices is to amplify low-level signals to the optimal line level.
When a microphone is used to record, the signal they produce is too low to be successfully be received by a recording device. Therefore, the signal requires amplification, to add gain and make it audible.
In the majority of cases, microphones require around 30-60dB of extra amplification to reach line level. If this amplification doesn’t occur, the signal will be too weak and quiet for the DAW or other recording software to play it back.
This is where preamps enter the picture. A preamp takes the signal from the microphone, provides it with the optimal amount of amplification, and then outputs it into the recording device.
Likewise, electronic instruments also require some amplification to reach the line level. It’s common to find preamps that are specifically designed to be used with a particular instrument.
There are many dedicated preamps out there, which are tailored specifically to the bass guitar, electric guitar, vocals, keyboards, and drums. Compared to a microphone, line-level instruments require less amplification, usually somewhere around 25dB.
Now, it’s important to note that not all preamps operate in the same way. We’ve established that the primary goal of this device is to raise the level of a signal in the cleanest way possible.
The method used to achieve this varies from model to model. For example, a bass guitar preamp will provide the exact amount of gain that is required for that instrument. It is likely to add coloration to improve the overall tone, too.
A headphone preamp, on the other hand, performs the vital function of amplifying the signal sent from a DAC (Digital-To-Analog-Converter) so that it can be received by the headphones, with minimal coloration added.
So there are preamps that simply perform the function of amplification, and there are other, more sophisticated ones, that are used to actually change the tone. For this reason, preamps are both dynamic and tone-altering devices.
What is an Audio Interface?
Audio interfaces are integral pieces of equipment for any form of digital music recording. Unless you’re blessed with access to a vintage analog mixing desk, then chances are you will need an interface to record.
Unlike the preamp, which performs the function of amplifying a low-level signal and potentially coloring the tone, an audio interface is actually responsible for sending the signal into a DAW.
It does this by taking the output from either a microphone, instrument or preamp, and transmitting the signal into the software, where it can be seen and heard as an analog waveform.
Audio interfaces come in many shapes and sizes, but there are some features that they all share. These are:
- Gain adjusters
- Headphone Output
- Phantom Power
The number of inputs included on an audio interface is usually directly correlated to its cost. More sophisticated interfaces offer an abundance of inputs, while more basic models may only offer one or two.
The advantage of having several inputs is that it allows you to record separate sound sources simultaneously. An interface with only one input is fine if you’re just recording vocals or guitar, but if you needed to use two microphones, it wouldn’t be capable.
Recording drums, for example, usually requires several microphones to all be set up at once, recording at the same time. A suitable audio interface would require enough inputs to facilitate this.
Modern audio interfaces connect to a computer or laptop via USB or Thunderbolt. Commonly, drivers are needed to be downloaded for the interface to successfully operate.
DAWs & Audio Interfaces
Digital audio workstations completely revolutionized the way that we record music. Before they came about, the recording would either be done using analog equipment or using a multi-track recorder.
DAWs and audio interfaces are interdependent with one another. Without a capable audio interface, it would be impossible to record audio into a DAW, such as Logic Pro, Ableton, or ProTools.
Likewise, without a DAW, an audio interface would simply be a playback device with no ability to record audio. Understanding the relationship between an audio interface and a DAW is important when illustrating the differences between it and a preamp.
Conversion & Connection
Audio interfaces are part of a sophisticated process that allows you to record into your chosen digital audio workstation. Preamps are also integral components, whether they are used externally or built into the interface’s inputs.
This process begins with a microphone, or instrument being plugged into the input of an audio interface. The microphone transforms the sound waves caused by vibrations entering its diaphragm into an analog signal.
This analog electrical signal then is sent down the XLR or jack cable, making its way into the input on the audio interface. This is where preamps enter the frame. One of the common causes of the confusion surrounding the differences between audio interfaces and preamps is that both are essentially reliant on each other.
The converted analog signal enters the input on the audio interface, where it is then sent into the onboard preamp. All audio interfaces require preamps of some description on their inputs.
An onboard preamp’s role is to take the low-level signal and add some heat or gain. As a result of this amplification, the signal is made strong enough to be successfully received by the DAW.
It’s worth noting at this point, that the preamps which are installed on the audio interface, along with the choice of microphone, will significantly impact the overall quality of the recordings.
High-end interfaces are likely to have better quality preamps installed than more basic models. This will affect the tonal characteristics of the recordings, their coloration, and also how clean the signal is.
The process then continues, as the now amplified signal is sent from the onboard preamp to the DAC. This device, which is also installed internally in the audio interface, performs the vital role of converting the digital signal to an analog waveform.
Digital signals consist of a series of 0s and 1s, which are sent through the connecting cable between the audio interface and the computer. Then the DAW is able to read the audio files, and they can be edited or processed using effects.
Almost immediately, the newly converted signal that came from the microphone is subjected to the same aforementioned process, but this time in reverse. The audio is sent from the DAW, through the USB or Thunderbolt cable, back into the audio interface.
The DAC then converts the signal back from digital to an equivalent analog waveform. The analog signal is compatible with monitors or headphones, so you are then able to hear what you have recorded through playback devices.
Preamp vs. Audio Interface – Comparison
When we analyze the functions of preamps and audio interfaces, it’s very easy to see why the two devices are often grouped together. They are both essential components of any recording rig where microphones are being used.
The main differences between the two devices are as follows. An audio interface is used as the front end device of your recording setup. It receives the signal from a microphone or instrument and subjects it to a conversion process so that it can be edited within a DAW.
Preamps are often built into the inputs of audio interfaces, but standalone ones don’t have the capabilities to record audio. External preamps are great for boosting a signal or adding deliberate color.
One thing that both preamps and audio interfaces have in common, is that generally speaking, the more you spend, the better quality audio you will have access to. Indeed, some people may like the sound that a cheap preamp or interface produces. After all, it’s a subjective matter.
If you’re hoping to achieve the cleanest, most accurate representation of your instrument or microphone, investing in an audio interface that houses high-quality preamps is essential.
Both preamps and audio interfaces have vital roles to play in any recording studio. The wonderful thing about the modern age of music-making is that anyone can gain access to an interface and start creating right away.
Over the years, I’ve slowly amassed a collection of preamps that are all suitable for different instruments or microphone types. They make a huge difference to my recordings.