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Tech Terms Demystified: Relating Gain to Level and Volume

Gabrielle Thorndyke started life at Crutchfield as a member of our award-winning Tech Support team, where she spent years translating rarified technical concepts into something real people can understand. She brought this deep understanding to bear during her time with the Crutchfield car A/V copywriting team.

Gain, Level, Volume...aren't they the same thing?

Everybody knows a volume control makes your music louder (or quieter), so why do there seem to be so many different ways to describe it?  If you're used to dubbing, or if making mixtape cassettes was your thing, you may remember "level" has something to do with volume. If you're into car audio, you may believe "level" and "gain" are just different names for "volume".

Why not just pick one term for the controls and cut down on the confusion? Because while these controls have similar effects, they accomplish different goals.

A gain control can be a beautiful thing if you like loud music, but it shouldn't be used as a volume control.  I talked a little about gain in my last post, and explained that a gain control doesn't change your audio signal, it just changes how well your amp picks the signal up. Better sensitivity makes it easier for your amplifier to pick up signal accurately. The richer, fatter signal is easier to amplify and less prone to distortion, so you don't have to use as much power to get a good result.

In other words, when you turn up your gain, you signal strength also improves, which makes your sound louder at lower power levels. Because of this, "gain" and "level" are often used interchangeably. While confusing, this usually isn't going to cause you problems (but if you're not sure a control does, always check your owner's manual - most are available online these days).

Audio level simply indicates signal strength. Signal strength is what lends substance to sound waves, so they hold together better and are easier for your amp to push. Level controls modify signal strength. As we mentioned above, this is sometimes done by changing input sensitivity (gain), but a more straightforward way is to change the amount of power a signal is fed. Volume controls work the same way.

I know what you're thinking: If they work the same way, what's the difference?

Ah, I was getting to that. You'll find a level controller most often in home audio equipment and professional recording gear, where it shines at tasks like volume leveling. Leveling can compensate for sound issues in an original recording, smoothing effects, or changing the emphasis of a particular track. Volume controls... well, volume. It make sound louder of softer, that's all.

A simple way of looking at level and volume is this: level controls fixed loudness (the volume going to the input side of your system), while volume controls variable loudness (the signal being output to your speakers).

If your TV (or cable) sound is hooked up to a receiver, try this experiment:
set the volume using your TV remote, then lay it to one side. You've just fixed your signal's loudness level.  Now, pick up your receiver remote and use it to change the volume going to your speakers.  This is your variable volume control.

We've already explained that a volume control works by manipulating the amount power going to your outgoing signal. The entire purpose of a volume control is to affect signal loudness - the amount of air in a sound wave times force it takes to push it. Turning a volume control up increases the force pushing your signal, so it sounds louder. Loudness is also that impact you feel when a big bass note hits - it's the physical component of your sound.

Remember that volume controls don't create new power, they just control the output. If your system doesn't have enough power to back up the volume you ask of it, turning up your volume will actually make your sound attenuate (that is, fade away to nothing).

If you want a really rockin' system but don't have a lot of cash, put your money into a solid, powerful amp and build from there. You'll get more bang for your buck, your music will sound better and the whole system will thank you.

And it's more effective than just making your amp go to eleven.

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