- What is a preamp used for?
- What does an audio interface do?
- Find out if you need one or the other (or both!)
- Also, check out our separate guide to DAC vs pre-amp.
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.
Audio interfaces are a step up from a computer’s inbuilt sound card in many ways.
Preamps are indispensable in recording setups. In pro audio, they are mostly used on microphones, that’s why people will often refer to them as mic preamps.
Let’s take a closer look!
What Does A Preamp Do?
A preamp increases (AMPlifies) a signal to line level before (pre) you record and process it. Without this process, the signal is too soft to record adequately.
To make this happen, gain is applied to the relatively low voltage of microphone or instrument signals like guitars or synthesizers, etc.
You can read more about this process in Line In vs Mic In (Line Level Explained For Dummies).
Types of Preamps
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.
If you want to get deeper into the techy side of things, check out our article on Tube vs Solid State preamps.
As usual with pieces of audio equipment, some preamps have built a reputation for having a particular sound.
To get you started on your research here is a shortlist of great external preamps/channel-strips for you to browse:
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
In comparison to preamps, audio interfaces are more versatile.
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.
If you want to learn more about why sample rate and bit depth are important, we explain them both in detail in What Sample Rate Should You Use? (+Myths & Misconceptions).
Digital To Analog Conversion
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)
The Focusrite Scarlett 2i2 Studio recording bundle gives you a great front end that includes everything you need to record.
- Super-low latency
- Intuitive halo feature
- Simple, compact, and eye-catching design
All those questions can be thrown in the mix together with a budget and the quality of the components and will hopefully spit out the best (affordable) audio interface for you.
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:
- 8 Best Portable Audio Interfaces (For All Budgets)
- 7 Best Professional Audio Interfaces
- Best 2-Channel Audio Interfaces (That Money Can Buy)
Sidenote: Standalone audio interfaces
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.
Wait, What About Audio Interface vs. Mixer?
Great question. An audio mixer takes your multi-track recordings and combines them together to create one or more output signals. An audio interface, on the other hand, converts the analog signals into digital signals that your computer can understand.
You can use an audio interface as a rudimentary mixer, but any professional studio will separate the roles here. It’s also possible to have a mixer that doubles as an audio interface, allowing you to bring multitrack audio into your DAW with ease.
Deciding Between An Audio Interface And A Mixer
Trying to decide between audio interfaces and mixers really comes down to one important thing:
It’s critical that you figure out exactly what you need this piece of technology to do in your studio before you buy anything. This guarantees that you are using the right tool for the job, eliminating a lot of headaches and hassle along the way.
For example, are you just making demos with your band at home? You may not need anything more than a simple two-channel interface.
Or are you going to be jamming with your bandmates and performing live? If so, you will want to make sure that you have total control over how each element of your band sounds in real-time.
In this example, your money would be best invested in an audio mixer.
You also need to think about things like how you’re going to signal route, how many hardware controls you need to actually manage each of the individual signals, and how many inputs you are going to have to deal with at any one particular point in time.
Can A Mixer Replace An Audio Interface?
These days, the overwhelming majority of audio mixer options out there can effectively replace audio interfaces.
Now, this doesn’t mean that every single audio mixer is going to be able to do the job of an audio interface. It’s just that the most popular devices on the market today do have those kinds of capabilities built right in.
This is why a lot of recording and performing musicians decide to get their hands on a quality digital mixer straightaway, using it in their studio set up while at the same time using it during live performances as well.
Yes, this approach is (often) a little bit more expensive – and it does require unplugging and then reconnecting your mixer whenever you have a gig. But this technology is definitely more of an “all-in-one” focus compared to a standalone audio interface itself.
The most important thing to focus on if you’re going to go in this direction is that you get a digital mixer with full multi-channel audio recording.
Not all mixers have this built-in, so don’t count on it. If you’re going to have multiple sources recorded at the same time – say two microphones and half a dozen instruments – you need to be sure that each of these individual channels is sending to your recording set up.
Digital mixers that do not have multi-channel audio recording are only going to send the main stereo mix to your device. That’s probably fine for podcasts or something of that nature, but it’s a nightmare to work around if you’re looking to multi-track an entire band.
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.
Do all microphones need a preamp?
There are microphones on the market that plug directly into your computer via USB. There will be some pre-amplification happening inside before it hits the computer, however.