February 01, 2023
One of the most misunderstood concepts in all of audio is the difference between gain and volume. It’s easy to misunderstand this distinction – after all in one sense they are the same basic thing. But there are key differences that are important to understand, especially when it comes to getting the tone you want. This is true whether we’re talking about guitar amps, studio recording, or mixing. Let’s clear it up here.
There’s really one difference between gain and volume, and that’s when they occur in a signal chain. Gain comes first. It controls the input level in a chain. Volume comes last. It controls the output level.
If you picture a mix console, this is easy to envision, because channels are laid out in order of the signal path. The gain knob is at the top of the channel. The fader (volume) is at the bottom. That seems obvious and it is, but here’s where the mistake is made.
It’s tempting to believe because the two “knobs” do essentially the same thing (make a signal louder) that the distinction doesn’t matter. But that’s not true. In fact, it matters a lot.
Going back to the console example, let’s say you’re mixing live vocals. Microphones output a very quiet signal, so they need a preamp to boost the level to usable levels at the mixer. The gain knob controls the input level of that preamp, which also controls how loud the signal is when it enters the next section (usually an EQ).
Imagine the singer starts to sing and your fader is most of the way down. You don’t hear much, so thinking it doesn’t matter much which knob you turn, you crank the gain up all the way. Now you still don’t hear much, but it also sounds bad.
Pushing the fader up, you hear more – the volume is now louder – but you can really hear how distorted the vocal is. Believe it or not, this has stumped more than a few young engineers. Now imagine the reverse. You have your faders up very loud, and still, the vocal signal sounds thin and weak. When you check the gain, you may notice that it’s not turned up at all.
It’s a simple distinction and it’s easy to remedy problems like this. Simply strike a balance. Use the gain to bring a signal to a good level with an acceptable tone, then use the volume to determine how much of that sound you’re hearing in the room. In essence, gain then becomes something of a tone control. There is some more complexity to the matter involving the physical differences between preamp circuitry and fader outputs, but it’s not necessary to get that deep here.
When it comes to an amp, the distinction between gain and volume is the same – gain is the input level, volume is the output level. In this situation, it matters even more. This is because gain, for a guitarist (or bassist), is a crucial tool for shaping tone.
Sometimes, it desirable to set your gain quite high to distort the signal and it give it just right amount of bite. Cranking your volume knob won’t do this. Similarly, you may be asked by the house sound engineer to reduce your stage volume. Contrary to popular belief, you can do this without sacrificing your tone. This is what the volume knob is for. Set the gain high to distort the signal the perfect amount, and then reduce the volume.
Or, if the opposite is what you want – a loud, clean signal – set the gain more reasonably and increase volume.
The distinction between gain and volume matters quite a bit in analog systems, but does it matter in digital systems like in your DAW? Yes. Admittedly, it often matters less, but it still matters. Consider a track in your DAW. Let’s say it’s a guitar track. You’d like it to be louder in the mix, so you crank up the fader. But should you have cranked the gain instead?
In truth, as long as you don’t clip the signal, it doesn’t matter. Manipulate the gain or the fader or both, it’s all just digital signal. However, the part about not clipping is important. You never ever want to clip a signal in digital audio, and it’s easy to do that with an unbalanced gain structure. So in that sense, the same thing can happen as happened in our example about mixing live vocals.
Bring the fader down too much, and crank the gain, you could clip the signal without really knowing it. Compounded over many tracks in a mix, and you may find your mixes are inexplicably noisy. Setting a balanced gain structure similar to how you would on an analog console helps with this.
There’s an even bigger reason to watch your gain knob in digital audio, too. Typically, signal passes from the gain section into a plugin section, where you do processing like EQ, compression, reverb, and so on. It turns out, most plugins operate best at a certain input gain (usually -6, -12, or -18 dB – check your plugin documentation).
Not to mention, clipping can get out of hand quickly when signal enters a plugin chain too hot and continues to get manipulated and boosted. So, once plugins are involved, that gain knob that bore no real distinction from the fader before becomes a crucial tool for maintaining a clean signal. For this reason, many digital mix engineers set all their gain knobs down a bit before starting a mix. It’s common for mixers to set all gain knobs down to -6 dB and some others do complicated calculations based on peak output from each track. However you go about it, it’s just as important to manage gain as distinct from volume in a digital setting as in the analog world.
Whether you’re dealing with amps, live sound, or mixing, understanding the difference between gain and volume may seem small, but it can be the key difference between getting exactly the sound you want and running around in frustrated circles. Hopefully this brief explanation helps!
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