Podcasting Basics: Episode 2 – The Audio Interface

Nemanja: Welcome to the Nootka Sound Podcast, I’m your host Nemanja Koljaja, a professional Sound Engineer, Audio Editor and Podcast Producer and a CEO and Founder of Nootka Sound, a professional podcast production facility. Today we’re talking about audio interfaces. So relax, get your coffee and let’s get into it. In the last episode, we’ve talked about how in order to record our podcast audio with our microphone we have to convert the electrical signal that comes out of the microphone into a binary code that our computer can read and for that we use an audio interface. First things first, many people are confused by an idea of an audio interface. Essentially, it’s a hardware device that is in charge of sound processing. Think of it as an external sound card that’s used to get the sound in and out of the computer. It can be connected via USB, Firewire, Thunderbolt or PCI connection. For podcast audio, the USB connection is the only thing you really need. When looking which audio interface to buy, you should consider quite a few parameters, for example how many microphone inputs do you need, how big is  your budget, do you need some other connections, for example MIDI or something like that. Having said that, let’s assume you’re a beginner podcaster and you’re getting ready to launch your first podcast. So, you’re either going to speak to guests remotely using Zoom or Skype, or you’ll have your guests come into your studio and record all of the audio locally.  Let’s assume in both cases you won’t be using more than two microphone inputs, one for yourself and one for your guest. So let’s take a look at couple of options. The ones that I’d recommend are Focusrite Scarlett 2i4 (2nd Gen), Steinberg UR242, PreSonus STUDIO 26 and Avid Mbox 4×4. Any one of these will set you back by anywhere from 150$ to 250$ and any one of them will be fine for your podcasting needs. All of those four interfaces use a USB connection and all of them have 2 inputs and 4 outputs and all of them are very similar. One thing I’d like to point out, and this is my personal opinion, is that the Steineberg one has the best preamps, so if you’ll be recording some lovely music with a good condenser microphone, I’d recommend that one. Having said that, the one I like the most is the Focusrite one, because I really like their home studio gear. They’re very accessible and the equipment is very reliable. And especially if you can get the bundle with the mic and the headphones that you can buy with the Focusrie Scarlett 2i4, I’d definitely go for that. #notsponsored So, now, let’s take one of them and break down all of the features. Give me a second to Google Focusrite Scarlett 2i4 and let me pull up a photo of it. So, let’s start from the back side. So on the back here we have a USB connector which you use to plug into a computer. This one uses a type AB USB connector and almost all of them use the same one. You’ll probably know it as the one that’s used for printers. We also have a MIDI in and a MIDI out. If you’re just recording audio, you don’t have to bother with MIDI. However, if you’re interested in learning more about MIDI send an email to info@nootkasound.online and we’ll make sure to record an episode on it in the future. Then we have 4 RCA line outputs and 2 ¼ inch TRS Jack outputs as well. Before we look at what they do, let’s talk about the actual connectors for a second.  An RCA or a phono connector provides an unbalanced connection, which in essence means it’s prone to picking up hum that can get into your signal. So that’s way it’s recommended to use a balanced connection, which in this case is a 3-pin TRS. TRS stands for Tip Ring Sleeve which are the three parts of the connector. Another example of a TRS connector is a headphone jack, it’s an 1/8 inch TRS connector. First two outputs are available through both the RCA and the TRS. So basically Line Outputs  1 /2 provide the same signal as Balanced main 1 and 2 outputs. You can use either to hook up to a playback system, however it is recommended to use the balanced outputs especially if you’re plugging them into studio monitors. Oh and in the audio world, monitors is a fancy word for speakers, so bear that in mind. For the connection between an audio interface and a monitor, you use TRS –XLR cables. TRS goes out of your interface and the XLR goes into your monitors. And then we have 2 additional RCA outputs labeled 3-4. So that’s the 4 outputs that this interface provides. Finally we have a K-lock or a Kensington Security Slot that lets you secure the interface so nobody takes it if you’re using it in a shared space. Let’s take a look at the front side. First we have two combo inputs. Combo inputs can receive both the XLR connectors and the TRS connectors. This is great, because you can use them to plug in a microphone or a line level TRS signal from your keyboards or even a Hi-Z (High impedance) TS signal such as a signal from a guitar or a bass guitar. Next to each input we have a big gain knob, a line / instrument switch and a pad. A gain knob provides gain or amplification to the input. Remember in the first episode when we said we have to amplify a low level microphone signal so it’s usable. This knob controls the amount of that amplification. Around the knobs, there’s an LED that indicates the amount of signal that’s going in. In the episode number 4 we’re going to discuss what’s the proper amount of gain and how to make sure you’re recording a strong and healthy signal into your DAW. The line / instrument switch is used for switching between a line level circuit and a high impedance circuit, and that only works if a jack is inserted, it has no effect on the XLR (Mic) input. So you would switch it in regards to what you’re actually plugging in. If you’re plugging in a guitar you’re going to use the instrument circuit and if you’re inserting let’s say the output from your mixer or an iPod you’re going to switch it back to line. And lastly, we have a pad button, which activates a pad circuit which in essence is the attenuation circuit. This is a useful tool when you’re recording a loud sound source and you’re not able to turn the signal down at the source, so you’re able to attenuate or lower the volume of the signal before it reaches the pre-amp and prevent it from overloading and causing distortion. The big knob on the right of the interface has monitor written above it and it’s a control knob for the amount of signal that’s being sent to the outputs 1 /2. Make sure it’s all the way to the left, and then turn it up slowly so you don’t blow your speakers. Then we have a headphone output that receives a ¼ TRS jack. You can switch the source of the headphone monitoring to either monitor outputs 1 /2 or 3/4. In the DAW you can assign which tracks you want to send to which outputs, but we’ll cover that in the next episode. The next thing we have is an input/ playback knob and it’s used to choose whether you’re direct monitoring or listening though the playback, which in most cases is a DAW. It essentially blends in the signal from the DAW and the signal that’s coming from the input. This is an important feature when recording music. You can use this feature to avoid latency and latency is a delay in the signal and it depends on a number of things, but most importantly the buffer size of a driver. So the smaller the buffer size the smaller the latency. But it can still be noticeable, especially when recording onto a pre-recorded track. That’s why you have the option to monitor the signal straight from the input, without any delay, and it’s called direct monitoring. Just make sure to mute the track in the DAW or to turn off Input Monitoring, because if you don’t and your knob is not all of the way on the left side that’s labeled Input you’re going to hear both the Direct Input Signal and the DAW Playback Signal. Therefore, the knob is used to mix between the two paths of monitoring. A practical example would be, when you’re listening to music or using your computer like you normally would you would have it dialed all the way to the right so you can only listen to the signal that’s coming out. Finally, the last thing we have is the 48V button, which applies 48V of power to both XLR Inputs. If you don’t know what you use this for, make sure to check out our first episode where we covered microphones. Bear in mind, when you press the button, there will be small voltage burst on the inputs. So make sure you’re not direct monitoring and that your monitor knob is turned down. Or if you’re using an analog mixer, you’d usually have mute buttons so you can mute each track and you would mute the tracks before turning on the 48V phantom power. The burst is not big, and I don’t know if it ever harmed any speakers, but it can be uncomfortable especially if you’re wearing headphones. Also, take care of your ears. Keep them safe, don’t be exposed to loud sources because you can seriously injure yourself and impair your hearing abilities. Ears are the best and the only irreparable tools of an audio engineer. One last thing to consider when using phantom power is that it applies voltage to both of the microphone inputs. So make sure you don’t plug in a microphone that can be broken down by a surge of voltage. The only microphones that you can break with phantom power are the ribbon microphones and they are a special type of microphones and you’re never going to see them unless you go into a professional recording studio, so you don’t really have to worry about it. The standard practice besides muting the channel that’s having the 48V enabled is to first connect the condenser microphone to the interface / a mixer and then turn on the phantom power. And after that when you’re done make sure to disengage the phantom power button and then disconnect the cable. This is just standard practice to ensure your microphone stays healthy and it’s good to take care of your equipment so it can last longer. For example, I’m recording this podcast from my home with a Focusrite Saffire 6 USB which I’ve bought in 2012 and it’s still serving me very well. Saffire 6 is essentially a precursor of the Scarlett 2i4.

That’s it! Thank you for listening, make sure you share the podcast with your friends and click that subscribe button so you never miss an episode! If you have any questions for us or suggestions about a topic we can cover related to the podcasting industry leave a comment below or send us an email at info@nootkasound.online. Also, make sure to check out our website, podcastproducer.org. Tune in to our next episode where we cover DAWs.  Peace out!