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What is a preamp used for?
What does an audio interface do?
Find out if you need one or the other (or both!)
Preamps and audio interfaces are both very important for any modern digital recording setup. You may be wondering why you see the two terms used alongside each other so frequently.
In this article, we’ll be diving deep into the differences between a preamp and an audio interface to help you get a handle on what the terms mean.
Preamp Vs Audio Interface: What’s The Difference?
A preamp is used to amplify an instrument or mic level signal to line level for recording.
An audio interface does a lot more than a preamp. Audio interfaces are designed to facilitate audio recording and monitoring with a computer, with inputs for microphones and instruments plus output sockets for studio monitors and headphones.
Almost all audio interfaces actually include at least one preamp so you can plug microphones and instruments directly in. You can even find preamps in guitar pedal form.
Preamps come in different shapes and forms depending on their intended use. For example, they are found in consumer products like stereos, mixers, and USB microphones.
But their basic function stays the same: make a weak signal stronger and usable for recording.
Of course, there are countless differences in sound, build quality, and design. External preamps may have multiple inputs, can use class A or class A/B amplifiers, use tubes or solid-state technology, and the list goes on.
An audio interface connects to a computer and allows you to record and monitor audio more easily than with an inbuilt sound card.
The job of an audio interface is to convert analog signals to digital data that your computer understands, and vice versa so that the digital audio data on your computer can be sent to your speakers or headphones. An interface will come in a range of connections such as USB-C
Audio interfaces give you XLR and TRS inputs, preamps, loudspeaker, and headphone outputs. Additionally, many audio interfaces also have MIDI In and MIDI Out ports.
The preamps on interfaces will provide 48V phantom power if necessary, let you adjust gains and volumes, and might even give you some visual feedback with fancy LEDs and lights.
But in most cases, their most important task is the analog-digital or digital-analog conversion to let you connect analog equipment like instruments, microphones, or speakers to your computer.
A/D & D/A Conversion
So, the task of an audio interface can be boiled down to the conversion of analog to digital audio (and vice versa).
Let’s look at the sound going into your computer first:
Analog To Digital Conversion
Analog audio hits your interface as a voltage, and is turned into digital data with an analog to digital converter (ADC).
The ADC takes snapshots in very short time intervals according to the sample rate. Common sample rates are 44100 or 48000 samples per second.
These snapshots are called samples, and you can think of them as like pixels but for digital audio waveforms.
The sample contains a value that represents the amplitude of a waveform at a given moment in time. The resolution of this value is determined by the number of bits that are used (typically 16, 24, or 32). This is also known as the bit depth.
Using more bits can give you a larger dynamic range. As a rule of thumb, every bit gives you an extra 6dB. That’s why a regular CD (44.1kHz sample rate with 16 bits) has a dynamic range of 96dB (16 x 6 = 96) which is enough for all types of music.
Before you hear the sound playing back from your computer, the audio interface has to convert it back to an analog audio signal that is sent to your speakers and headphones.
As you might have guessed, this process involves a digital to analog converter (DAC). The value of each digital audio sample is matched with a voltage, creating an analog audio signal.
Hence, audio interfaces combine ADC and DAC components to allow you to record and monitor digital audio.
What To Look For In Audio Interfaces
Audio interfaces might lack the excitement of new instruments or plug-ins, but in most cases, it makes sense to spend some time (and money) on them.
The audio interface often is the center around which all of your studio gear revolves, especially if your interface has MIDI. You may have great instruments, microphones, loudspeakers, and a powerful computer, but every signal has to go through your interface.
Which leads directly to the next point: What are the specific requirements for the audio interface in your studio?
Do you want to record audio with the interface? Or are you just mixing?
How many channels do you want to record at the same time?
Are you using or planning on recording with microphones that need 48V phantom power?
Do you have two sets of speakers and want to be able to switch between them?
Do you need more than one headphone output?
Do you need a standalone audio interface? (we will get to this in a second)
There are many products on the market and it can be tedious to find the perfect one. Try to be honest with yourself regarding which features or how many inputs you really need and consider investing a bit more in quality over quantity.
Remember, audio interfaces are the heart of any modern digital recording setup.
To browse some interfaces within your budget, check out:
Some products are advertised as being “standalone audio interfaces.” This means they can work without a computer and generally have a separate power supply.
These standalone interfaces are good for setups that involve custom routing and split monitoring. They may also provide onboard DSP effects like equalization and reverb.
External Preamp vs Audio Interface – Which One Do I Need?
First of all, let’s talk about the elephant in the room: why should I buy an external preamp when there are (often multiple) preamps already built into the audio interface, which I need anyway? There are several reasons:
More gain: external preamps often provide more gain which can be especially interesting when you are using low-sensitivity dynamic microphones that produce weak signals
Quality: high-quality analog preamps will stay clean and transparent with little to no distortion even when applying high amounts of gain.
Less noise: a low noise floor gives you more dynamic range and better sounding results.
Coloration: famous external preamps are known for the special flavor, warmth, or air they add to recordings.
So, if you are trying to improve the sound quality of your recordings and lift your productions in this area to a more professional level, an external preamp is the right choice for you.
The preamps on audio interfaces just have to be “good enough,” however many interfaces use the quality of their preamps as a selling point, so go figure.
Also, keep in mind that your recording quality will only be as good as the weakest link in your chain.
Do audio interfaces come with preamps?
Yes. Unless it’s a very basic one, you can expect preamps to come with your audio interface.
Do I need a preamp and an audio interface?
Almost every audio interface will have preamps built in. If your goal is to simply get audio into your computer, these will do just fine.
If you consider yourself an audiophile or just want the most professional results possible, you can consider getting an external preamp before it runs into your interface.
Is an audio interface the same as a preamp?
No, audio interfaces have preamps built into them to amplify analog audio signals before they are digitized.
A preamp is also unlikely to have any digital components, but an audio interface is made to work with digital audio equipment (like your production computer). Some audio interfaces can function purely as preamps but this is not their primary purpose.
Does a preamp improve sound quality?
Yes. Preamps are needed for boosting instrument level signals to line level. Without this step, the audio would be too quiet when you record it.
An external preamp can make a considerable difference in the sound quality of your recording. They can be quite expensive, though.