A preamp is a device that amplifies a low-level signal to the optimal line level. On the other hand, every audio interface has a built-in preamp. The main difference between the two is that preamps are mainly used for improving audio quality (by amplifying audio) whereas interfaces act as a hub for connecting external instruments to your computer.
Preamps are not as crucial for a studio setup, but they improve sound quality and elevate your recordings. Comparatively, an audio interface is a lot more versatile and offers a complete recording solution. Audio Interfaces are how modern studios record music, as well as podcasts, and everything else.
Generally speaking, an external preamp is more expensive than an audio interface, even though interfaces also include built-in preamps and allow for inputs, outputs, volume control and a low latency. This makes audio interfaces a better option to start with. However, sometimes a dedicated external preamp may be the better way to get the desired results.
What is an Audio Interface?
An audio interface is at the center of all audio processing. It is a device used to plug in external instruments or mics, enabling you to record music by sending the input signal (in a digital form) to your computer and then playing it back through your monitors.
Audio Interfaces are used to record music in a studio setting as well as live music performances, streaming, and podcasting. Interfaces let you easily record and playback multiple audio channels at once while also allowing you to export any recorded audio into your DAW.
The built in preamps in an interface take the incoming signal, which is usually quite low, and increase it to a usable level. Low quality preamps (usually found in cheaper interfaces) will result in a low quality sound (bad tone and saturation). They may even add color which is not ideal in a studio setting. Interfaces with the most neutral preamps are always held in high regard by audio engineers.
In addition to preamps, converters are an important element of an audio interface. A DAC(Digital to Analog Converter) is a component that translates digitally stored information (audio from your computer) to analog, so you can hear it through your headphones or speakers. On the other hand, an ADC (Analog to Digital Converter) takes an analog signal, which has the form of infinitely varying frequencies like a mic input, and converts it into a digital signal that your computer can process.
What is a Preamp?
A preamp’s primary function is to amplify an analog mic-level signal (-60dB) to an analog line-level signal (+4dB) for further processing. When you speak into a microphone, the analog signal itself is very quiet, and needs further amplification (also referred to as gain) to reach the audible range. This is where preamps come in.
Generally, mics require about 25-65 dB of additional gain to reach the established +4dB line level. A preamp simply receives an audio signal, amplifies it to the appropriate level and transmits it to the converters. These converters then take the amplified signal and send it to the DAW.
A good preamp usually provides a high maximum gain range (also referred to as headroom) without drastically altering the input signal. The amplified signal should be noise-free and contain the same details. Bad quality preamps will often generate a random noise and may cause distortion/clipping at higher gain levels.
Preamps can be internal and external. An internal preamp is a circuit within a device such as mixers, microphones, and audio Interfaces. On the other hand, an external preamp is a standalone unit that features more elaborate circuitry and has slightly more controls/features. External preamps are usually found in professional recording studios.
While most preamps seek to preserve the exact audio signal with extreme transparency, some may color the track. They have multiple ways to do this which include boosting/blurring certain frequencies or altering slew-rates. It can also be an indirect effect that results from the quality of the components used such as the op-amps and transistors. This color can make your audio sound warm, airy, thick, etc. Whether the preamp’s coloring effect actually improves audio quality is subjective.
Differences between an Audio Interface and a Preamp
Preamps and audio interfaces are both tools for improving audio quality. However, there are some obvious differences between the two. These distinctions are due to differences in their drives and functions.
Preamps enable us to amplify a quiet, mic-level signal to a louder line-level signal. An audio interface, on the other hand, is a multi-purpose tool. It can be used to monitor audio files, convert data forms, and control volume levels.
The main differences between an audio interface and a preamp are presented in the table below
|Preamps are dedicated to amplifying your sound as cleanly as possible. They amplify quiet signals (mic level) from a microphone to an audible standard operating level (line level).
|An audio interface is a much more versatile tool (dedicated to getting sound in and out of your computer). The main function is to transmit audio signals between different inputs and a computer, then getting playback (through a DAC)
|External preamps do not transmit audio signals to your computer. They need to be routed through an audio interface, mixer, or a standalone ADC.
|An audio interface directly transmits signals to your computer (without an intermediary) through a USB, Thunderbolt or a Firewire port.
|External preamps have advanced features such as polarity inverters, high pass filters, pad buttons, input impedance dials and tone controllers.
|Audio interfaces only have basic preamp features (controls) such as gain dials and 48V power toggles for condenser mics.
|Preamps are generally more expensive than Audio Interfaces. The cheapest unit costs around $200 and some of the more popular models such as API and NEVE can set you back a few thousand dollars.
|There are a lot of cheap yet low quality audio interfaces that go for as low as $50. Mid range interfaces cost around $250 and high-end brands like UA and Apogee cost more than $500.
|External preamps alter the signal in a specific manner to achieve a desired effect (Also referred to as color). They are sought after for this quality.
|Audio interfaces are built to achieve absolute transparency. Only cheaper interfaces add color (this is not a desired trait)
Choosing The Right One for Your Needs
To summarize the debate over preamps vs. audio interfaces, it really comes down to what your setup already includes.
In general, if you’re just starting out as and haven’t figured out a way to connect your different instruments/mics to your computer, then you should go for an audio interface. It’ll be at the core of your recording setup providing you with all the necessary tools to export quality tracks into your DAW. If you already have a decent audio interface/mixer, good recording gear and simply want to refine your sound quality, then an external preamplifier is the way to go. It’ll provide that extra nudge that’ll make your audio sound more professional.
For someone who is just starting out, investing in a high-quality audio interface is a better option than buying an external preamp. While a preamp only affects the recorded mic/instrument signal, an audio interface contains several components which are vital for achieving and retaining a great sounding track. So even if you get the best preamp out there and pair it with a cheap interface, you’ll still lose a lot of sound quality due to cheap converters and bad audio drivers.
Keep in mind that every audio interface includes an internal preamp. A preamp is simply designed to enhance the quality of your recordings and provide you with great tracks that you can edit in your DAW. In comparison, an audio interface is a more versatile device that can process multiple inputs, communicate data signals and also boost your recordings’ sound quality.
Overall, if we ever had to rebuild our recording studio from scratch, our top priority would be getting a powerful audio interface that’ll be at the core of our setup. Everything else would simply pertain to it including any external preamps which would only be peripheral units.