When it comes to music production, recording, audio theory, there will always be things to learn. In a smaller or larger scale, anything will influence your work. From setting up a proper studio acoustic, going through checking the equipment, until the final rendering steps. From my own experience I've learned that to master everything, you need a lot of research and practice. Unfortunately, one of the most overlooked steps of recording/ production process is probably the one you should worry about the most. I'm talking about gain staging, the focus of this article. You ever wondered what it is and how does it affect your work? If you don't, maybe after today you'll look into this subject differently, as it plays a major role in your work, from live music to studio recording.
What is Gain Staging?Also known as gain structuring, it is the act of setting the gain of each amplification stage in a sound system to achieve a target system volume that minimizes noise and distortion. That doesn't sound that complicated right? Putting in other words, achieving a good gain staging allows your sound system to reach the best signal-to-noise ratio. But how exactly do we get there? Sometimes isn't that simple. Because in this process you will try to reach the loudest peaks possible, but without clipping. In order to do that, there are various steps and principles involved. You have to consider each part of your sound system. But don't worry, stick around and we'll learn more about gain staging.
First steps in Gain StagingSetting up an appropriate gain structure means you will attempt to minimise noise and distortion accumulated along the chain and its multiple gain stages. Although some distortions are desired, the purpose here is to significantly cut or minimize the unwanted ones. Any point where signal passes through an amplifier can generate unwanted noises and potential distortion to the final audio. That's mostly due to the random movement of electrons within the components. It may not sound like an issue for you at the very beginning, but as the signal passes through the various components of your recording room, that noise can turn into a real headache. I can't really tell you which component is the one you should worry about the most. That's because, from microphones to the mixer's preamp, pretty much everything counts. That's why you have to optimize the signal that passes through the different systems. Further on this article we'll cover more about this subject.
Key concepts in Gain StagingSo now we know what gain stage is, let's see what else. If you like to understand more about some of the key concepts that are part of the gain staging subject, take a look below. I'll just mention terms superficially here, but if you really want to understand how to structure proper gain from the instrument to the DAW, you should look a little deeper into the following:
- Noise: Any unwanted sound in your signal is considered noise. Best way to avoid it is to eliminate unnecessary gain stages. If that's not possible, try to eliminate by amplifying it as little as possible;
- Noise floor: We have a really nice article on noise floor. If you haven't read it yet, I recommend you check it out here;
- Distortion/ Clipping: It happens when you overload signal on any gain stage;
- Peak/ RMS: Those are two ways to measure the signal strength. take a look at the loudness concept;
- Nominal Operation: The nominal operating range of any gain stage is the optimal average volume (RMS) that circuit works with. That is usually the professional line level,+4dBU;
- Signal-to-Noise Ratio (SNR): Is the proportional amount of dB between the nominal operation level and the noise floor. The higher the SNR, the farther the noise is from your actual signal;
- Headroom: is the difference between the nominal operating level and the clipping point;
- Unity Gain (U): It is said that you achieve Unity Gain when a piece of equipment neither boosts nor cuts the incoming signal. That way, you affect the signal as little as possible.
How to achieve the best Gain StagingNow that we know what it is and what's involved in the gain staging structure, let's see how to optimize it. You have to make sure that the gain in each stage of electronic processing within a signal path is optimised to keep the signal level well above the noise floor, but accordingly below the circuitry clipping point. For that, you can start by choosing the spot with the best SNR (signal to noise ratio). For microphones, for instance, you can try to keep them as close to the source as possible. That way, you’ll get a stronger signal and pick up less noise. As we're on the recording subject, let me tell you that it’s ok if you don't record close to the maximum volume handled by the digital system (0dBFS). Bit resolution is not exactly a problem as it was due to 24bit recordings and floating bytes. So, if the noise floor is boosted near maximum volume more than it should, that's probably due to electronic components noise or components age, so you might wanna look into that. Still on the recording subject, apart from the exceptions, it’s OK to record (DAW) with your peaks somewhat close to the max, around -6dBFS and -10dBFS, without clipping. But if you're planning in recording lower than that, it's ok too. Actually, it’s encouraged by many professionals to record with max peaks from -14 to -20 as it helps to mix. So there’s no need to lower the instrument’s levels with a trim/gain plugin or with track gain, as they are close to how they’ll need to be when mixed. It also emulates the headroom of analog gear (18-20db).
PeripheralsNow that we have covered the first gain stages, let's see what else we can do. With peripherals, I recommend you to work within their recommended region (0dBVU, above that is red flag, despite the equipment’s headroom). You can perceive that on its VU (check Magroove’s decibel article for more infos on VU adequate levels). I know that all that must sound hard, I mean, optimising gain structure. It actually is. You have several bits of gear connected together, and you must ensure that every circuit is running at its optimum signal level, while still leaving the appropriate safety margin. Magroove tip to help you a bit more in this endeavor: always match impedances and levels. Instruments on instrument inputs or on line inputs through Direct boxes, mics on mic inputs, instruments with line outs or peripherals used in mixing always use the line ins and line outs of the interface. Also, match operational line levels (+4dbU or -10dBv) adequately. It may be not much of a big secret for you, but keep in mind that not everyone has the level of expertise that you have acquired during the years working with live audio and studio.
Classic/ standard Gain Stage structureThis far we've covered a good amount of information on the topic. Now let's begin wrapping things up. For starts, I would always recommend to start dealing in each channel by setting the channel fader to unity gain and then bringing up the mic pre until the input is at an ideal nominal operating level. At least that's far better than setting up a mix from the preamps and then mixing again from the faders. Let's see a few other quick tips below:
- Apply Pads and Filters only if really necessary. Just keep in mind that this gain reduction doesn’t affect the noise floor, but it decreasing the signal-to-noise ratio, so you don’t want to use the pad unless it’s absolutely necessary;
- Learn how to properly manage EQ settings. If you don't intend to use EQ after the preamp, just bypass it, as you will avoid unnecessary gain stage;
- Learn how to properly operate outboard compressors, effects units, and other processing equipment;
- Learn about mixing. The more signals you have, the more complicated it gets. So learn how to keep the hottest signal in the mix at unity and mix the rest of your tracks by cutting levels;
- Learn how to properly set up the power amp. Assuming you have access to it.