What is an interface?
An audio interface is like the brain of your recording studio. It’s the one piece of hardware that connects all your microphones, guitars and audio gear to your computer. Your interface converts your analog signal ie. your microphone or guitar, to digital ie. your computer. It also performs the same process in reverse. That is, it receives the digital audio from your DAW (Digital Audio Workstation) and converts it into an analog signal that you can hear back through your speakers or headphones. This is also known as an AD/DA Converter (Analog to Digital -Digital to Analog). Depending on your interface, those signals are sent and received via a thunderbolt, USB or firewire connection.
You will also find preamps for providing power (phantom power) and gain to a microphone signal.
So what is a Preamp?
A preamp (pre-amplifier) converts a weak signal into a stronger signal that can be further processed to a power amplifier and a loud-speaker. Four example, it can take a weak signal from a microphone and make it loud enough to send through your interface without introducing noise. There are different types of preamps. The most common are solid state and tube. You will find most interfaces possess solid state microphone preamps, but you can also buy outboard preamps like tube pres that will colour your microphone signal differently.
Depending on the interface and the price, you can find one that has between 1 – 16 microphone inputs. The interface also possesses outputs for your monitors (speakers) and head-phone. They have their own dedicated headphone outputs, some with two (one for the producer and another for the talent). So if you’re just recording a vocal and guitar, a two channel interface will serve your purpose. However, if you’re thinking that you might want to expand later and record more inputs simultaneously, like a drum kit, you’d want to invest in a bigger interface with at least 8 microphone preamps, such as a pro40.
The interface I have here and highly recommend is the focusrite Scarlett 2i2.
This preamp is priced around $300 and has two preamps for your microphone inputs, two outputs for your speakers and a headphone output. You’ll also notice this 48V button. This is phantom power. Phantom power provides a boost in power to your microphone. In most cases, modern condenser microphones will need this switch engaged to allow it to work correctly.