What is it?
Recording interfaces are essentially soundcards that allow you to input audio into your computer and output audio from it.
Many recording interfaces have preamps built into them, which power microphones.
The price of recording interfaces is often broken down into cost per preamp. For instance, a $1,000 recording interface with 2 preamps built in has a cost of $500 per preamp.
The interface above has no inputs in the front. It has two inputs in the back. One is an XLR input, on the right side. To the left of it, is a 1/4″ input. Microphones usually use XLR connections and instruments such as guitars usually have 1/4″ connections. Some interfaces may also have a midi input.
The interface pictured above has a 1/4″ headphone out in the front. It also has 1/4″ line outputs in the back, which are standard on most studio reference monitors. Some studio monitors may have an XLR port for audio in, but XLR to 1/4″ cables are easy to find and do not result in loss of quality.
Sample Rate and Bit Rate
Samples rates and bit rates are a very technical matter and all you really need to understand is that higher sample rates and bit rates result in marginally higher quality recordings.
CDs are 16bit/44.1KHz and most recording engineers prefer to record at a slighly higher bit rate and sample rate just because it makes them feel better. In the end, you have to down-convert everything down to the CD compatible bit rate and sample rate.
I personally recommend 24bit/96KHz as that is probably the most common combination. The difference in quality is practically unnoticeable to the untrained ear.
If a recording interface has a preamp built-in, it may or may not have phantom power on that preamp. Phantom power is required to power all condenser microphones, which are widely used in studio recordings.
It is almost an essential feature on your preamp. However, if you’re not planning on using your interface’s built-in preamp, you don’t need to worry about it having phantom power. The phantom power on and off switch is usually denoted by a ” 48v” on most music equipment.
USB vs Firewire
If you plan on using live effects, where the sound goes in from your microphone, gets effects applied live inside your computer, and comes back out of the speakers in its modified form, you may want to consider the latency of the process.
Latency is how long it takes for sound to come back out of your speakers after being picked up by your microphone. In live settings, it is crucial to keep latency at a minimal. Anything more than 30 milliseconds can easily be noticed.
Firewire is almost always a better choice than USB in terms of latency. However, Firewire devices are getting less popular and USB recording interfaces dominate the market. Firewire ports are also hard to find on computers.
If you absolutely need to monitor your processed audio live, Firewire is the way to go. Otherwise, USB works great.
Some interfaces have built-in DSP effects. This simply means that the recording interface has built-in effects inside it that take no toll on your computer’s resources.
This can be very beneficial if you have a slower computer. However, I have found these effects to be subpar quality and most interfaces do not offer them.