Gain can be a very complicated topic, so in this article, I will try to make it as simple as possible.
1. What is gain?
Simply put, gain is how much you are amplifying (or increasing the level) or your microphones output signal. This is necessary because microphone's output signals are very quiet, and you need to get this signal to a level that you are able to work with in post production.
2. Factors that impact gain requirements.
I receive the question "What's the best gain to use on this microphone/preamp", and to tell you the truth there is no absolute answer there. This is because there are multiple factors that impact how you set your gain.
- Loudness of the sound source: If you're recording someone whispering, the sound source will be quiet and you will need more gain. On the other hand, if you're recording a guitar amplifier with the volume set to 11, you will need significantly less gain.
- Distance between the sound source & the microphone: The farther away the sound source is from the microphone, the quieter the audio that is being picked up. Therefore, if you are 6 inches away from a microphone, you'll need less gain than you would if you were 10 feet away.
- Sensitivity of the microphone: Sensitivity of a microphone tells you how loud the output signal of this mic is. Dynamic & Ribbon mics typically have a quieter signal when compared to condenser microphones. So if you're using a dynamic, you'll need a higher gain than you would if you were using a condenser.
3. What level should you record at?
I've heard many people say "Record so you're hitting -18dB on your meter", others have said "Record at -10dB" and others say "Record at -6dB". Regardless of what level you choose, when this is being said, it means you are recording so your peaks (the loudest parts of your recording) hit -6dB, -10dB, or -18dB.
The reasoning behind this is to allow for headroom. Headroom is nothing more than the difference between the loudest part of your recording and 0dB, which is where your recording will begin to clip.
For example: if I am recording spoken word, and I set my preamp gain so I'm hitting -10dB at my loudest, then my voice can unexpectedly get 10dB louder before I begin clipping/distorting, ultimately ruining the recording.
It ultimately comes down to how dynamic the sound source you're recording is. If it is a sine wave that does not change volume, you can probably set your preamp to record around -1dB or -2dB. But if you're recording an expressive singer that goes from soft singing to screaming in a single take, this can vary drastically in loudness, so you may want to set your preamp so you're hitting -10dB or even -18dB.
4. How does gain affect your sound?
There are many schools of thoughts, and arguments to be had regarding coloration of preamp on your recordings, but we're going to avoid those in this article and focus on the more noticeable impact on your recording.
- Setting your gain too high: When you set your gain too high (i.e. so you're hitting -1dB on your meter), this does not allow for any wiggle room. You have to remain consistent in your levels, and if you get excited and begin to speak loudly, your signal will exceed 0dB and clip or distort.
Once you have recorded something and it contains clipping, there is nothing that can be done to clean up that recording. You're stuck with it. So I would always suggest you err on the side of caution and record slightly quieter than you think you need.
- Setting your gain too low: This issue seems to be less pervasive online, but if you set your gain too low and you're using a subpar preamp with a high noise floor you risk losing, or mixing your signal in the noise floor.
What this means is that if your preamp has a noise floor of -50dB, and you're recording so you're peaks are hitting -30dB, you're going to run into some issues. This is caused because in post, you're going to have to boost this recording by ~30dB. This means that your noise floor is no longer -50dB, but it's been boosted so it will be -20dB. So just remember, when you're boosting your recording in post, you're not just boosting the recorded sound source, you're also boosting the noise that's introduced by your preamp.
I think that should give you a basic framework to work off when you're setting up your preamp/interface before recording a podcast or youtube video. Until next time, may your recordings have no clipping, a low noise floor, and contain good content. Good luck.