The goal of this article is to help you shop for an audio interface. These concepts can get very deep, but for now I will keep to some of the more basic points about the subject. Here are 9 questions you should ask yourself when comparing audio interface options.
1. How many instruments do I need to record at the same time?
The first thing you should consider is the environment that you will be working in and how many instruments you need to record at once. Some people only need the ability to record 2 tracks at a time and others need a minimum of 8. This is the first and most crucial step to understanding your set-up.
*Note* Hardware companies advertise their products as having x-amount of inputs and y-amount of outputs.
For example, you may see this in the specifications for an audio interface:
- [Product Name] 10×6 Inputs/Outputs
- [Product Name] 16×8 Inputs/Outputs
- [Product Name] 8×4 Inputs/Outputs
This does not mean that you can record 10, 16, or 8 inputs at once. It is a way of telling the end user how many connections are on the product itself. Hardware companies can up the number of inputs on a device if they include the following:
- Hi-Z inputs that override microphone inputs
- Line inputs that override microphone inputs
- Effects returns (No microphone pre-amp, just AD converters)
- Headphone Outputs
You need to look for the term “Simultaneous Audio” in order to understand how many inputs a device can record at the same time.
In reality, a device may actually have these types of specifications:
- 10×6 Inputs/Outputs (8 Simultaneous Inputs, 6 Simultaneous Outputs)
- 16×8 Inputs/Outputs (12 Simultaneous Inputs, 8 Simultaneous Outputs)
- 8×4 Inputs/Outputs (4 Simultaneous Inputs, 4 Simultaneous Outputs)
Make sure to look out for this, it could really throw a wrench into your budget if you don’t.
2. What kind of connections do I need for the instruments I’m recording?
For the most part there are 4 basic types of connections that you will need to look for when shopping for an audio interface:
- XLR and XLR/TRS Combo – If you are looking to record acoustic instruments then you will need to buy a microphone and an XLR cable to use the XLR plug on your audio interface. Audio interfaces that come with Combo XLR/TRS jacks are great because they take 2 types of connections in one.
*Note* Make sure to check if your microphone needs “Phantom Power” and if your audio interface supports this. Some interfaces label this as “+48v”.
- TRS – For use of instruments that do not need a preamp. Look for this type of connection in the event that you want to record non-acoustic instruments like keyboards and sound modules.
- Hi-Z – Used for Guitars, Basses and any other high impedance connections.
3. What are outputs, and what do I use them for?
Outputs are used mostly for listening to the audio coming out of your recording program.
Examples of outputs are:
- Headphone jacks
- Main Outputs
- Sub Outputs
- Outs labelled 1-2, 3-4, 5-6, etc
These connections are typically XLR or TRS connections. This is where you would connect things like Studio Monitors, or external effects processors.
4. What kind of connection does my computer need to connect to an audio interface?
The most common types of connections needed are USB 2.0, Firewire 400, and Firewire 800. These all stream data at different speeds but in the end tend to get the job done pretty well.
When shopping for an interface check to make sure it has the same connection your computer.
5. Do I use any devices that require MIDI connections?
Some examples of MIDI devices:
- Rack Mountable Synths
- Drum Machines
- Effect Units
- Guitar Amp Simulators
- General MIDI Sound Modules
These types of hardware units require MIDI connectivity such as MIDI In, MIDI Out, and MIDI Thru. For the most part, MIDI In and MIDI Out are the two most used and common types of connections needed on an interface.
*Note* A lot of MIDI Devices these days connect to a computer using USB, but older units tend not to have the USB connections.
6. What Sample Rate am I mostly recording at or working with?
a. Term you should know
Sample Rate – A sample rate is a measurement of samples taken from an audio signal over time. Humans can only hear up to 20kHz. To properly represent an analog signal in a digital domain the sample rate must be at a minimum of double the range of the human hearing. This is why 44.1kHz is the standard sample rate for any hardware interface.
Some audio interfaces support Sample Rates up to 96kHz or even 192kHz. These sample rates produce higher resolution audio.
b. Should my audio interface support high sample rates?
The following examples outline a couple scenarios where having a piece of hardware that is flexible across many sample rates is important:
If you are mixing your band’s record that was recorded at a high-end studio then they may have tracked your entire band at 96kHz and given you just the project files. If your audio interface does not support 96kHz then you will not be able to open your project up without some headache or strange behavior. Owning an interface that supports up to 96kHz could be a great investment so that you can open up just about any project that is given to you.
When working as a freelance recording engineer you may be asked to record at a minimum of 192kHz for reasons of clarity and high fidelity. Some major touring Orchestras and Choirs do this as a standard. Obviously this is a pretty specific scenario, but if you are not equipped to deliver on that kind of work as a freelancer, then you may miss out on some opportunities.
You may not encounter either of these scenarios but it’s important to be aware of this kind of stuff before you invest in expensive hardware. Recording and mixing at 44.1kHz is just fine, but if you are looking to spend some extra money on an interface that can record higher sample rates then go for it!
7. Am I going to need more inputs in the future?
Expandable interfaces are usually a bit higher in price but could be useful in the future if you want to integrate it into a more serious setup. The types of connections that will allow you to sync multiple devices together are the following:
- ADAT – 8 Channels at 48kHz
- TOSLINK – 2 Channels
- D-Sub – Depends on manufacturer’s spec
- AES/EBU – 2 Channels
- SPIDF – 2 Channels
When going down this route you should definitely consider clocking. This is the first thing most users will run into when daisy chaining multiple digital devices together. One piece of hardware should send clock to the other via one of the digital connections or (if available) a BNC connector. This keeps the two devices in sync with one another. Without a proper clocking method you will experience “jitter” – which is the sound two digital audio devices working together at different clock speeds.
Some audio interface manufacturers allow their devices to be synced together when both are connected to a computer at once. The drivers on the computer manage the synchronization. Obviously this is a rather new and very specific occurrence, but it does exist.
8. Does my interface need to be portable or not take up that much room?
The size and portability of an audio interface is definitely something to consider when first shopping for a device. Check out audio interfaces that are Bus Powered and do not require their own power supply. They could be especially useful when you are sitting in a place where only one power outlet is available (Airport Terminal, Tour Bus, Train). Interfaces that are bus powered are great for taking with you on the road because most of them are small and sometimes even fit in your back pocket.
Larger audio interfaces that are portable typically will take up 1 or 2 spaces in a rack. These will ship with rack ears or have rack ears available for installation. Most of these audio interfaces are not bus powered and have their own power supply. In the event that you have a few of these then it’s important to purchase a Power Conditioner. Think of it like a power strip for your rack. It keeps voltages regular and will save your audio interfaces from getting fried by an insufficiently powered outlet.
9. Should I purchase a sound card or an audio interface? What is the difference?
A soundcard is the system on your computer that handles all of your sound. An audio interface connects to your computer through USB or Firewire ports. One is internal and the other is external.
Soundcards stream audio from the internet, games, applications, and anything else that requires basic audio playback. For the most part, stock sound cards are compatible with MME(32bit) Drivers. MME(32bit) Drivers are not the recommended driver mode for Digital Audio Workstations because their functionality is limited. Most Digital Audio Workstations require the use of an ASIO compatible device.
When shopping for a brand new sound card make sure that you are purchasing it from a pro-audio company if your intentions are to record and mix within a DAW. Some high-fi companies produce sound cards that will say ASIO compatible. The best way to know if your sound card can be used with recording software is to read it’s manual or technical specifications. This is where it will list what recording programs are compatible with your device.