What Is A Gain Control? (It’s NOT a Volume Control)

What’s your first move after getting a new amp installed? Find the gain knob, crank it to 11 and party! Otherwise you’re just wasting power, right? Here’s some news: setting your gains incorrectly doesn’t only hurt your sound quality, it will damage your gear as well. A great car audio system requires proper tuning and gain controls are a big part of that.  Get ready for a crash course in amplifier gain controls.

What Is A Gain Control?

You already gathered from the title that a gain control is NOT a volume knob… So what is it? First, let’s take a step back and understand the amplifier’s structure. An amp can be simplified to two stages with different goals:

1. Input stage: Listens for a signal
2. Output stage: Produces a louder signal

Your amplifier’s power rating describes how much power the output stage can deliver to your speakers, if given an ideal signal level. This is where the input stage comes in.

Listening for a signal sounds simple, right? The difficulty arises in dealing with different voltage levels from various head units (sources). How can one amplifier work universally? Enter the gain control.

The purpose of a gain control is to tune the amp’s input stage to accept the head unit’s voltage level. Think about it like a cellphone conversation.  Your job is to listen to the person on the other end. With phone turned down too low, you can’t hear the other person over the background noise around you. When it’s turned up too high, the other person sounds distorted and is difficult to comprehend. There’s a sweet spot in between, where your friend can speak at a wide range of volumes and still be understood.

Amp gains work the same way – too low, and the background noise, or “hiss” takes over  Too high, and music becomes distorted even at a normal volume level. Just like the phone conversation, there’s a sweet spot where you can use a wide range of volume from your head unit without too much hiss or distortion.

“Cranking” Your Gain Controls Will Damage Your Gear

Amplifier gain controls are sometimes referred to as Input Sensitivity

If cranking the gains results in a bit of distortion, how does it risk damaging your gear? Distortion, or “clipping”, drives much more power through your amp and speakers than an un-clipped sound wave at the same volume. Without getting into messy calculus, you can experience this by swinging your arm back and forth while holding a weight. Swinging smoothly isn’t difficult. This mimics how a speaker moves in and out to create a sound wave. Now repeat the same motion, but pause for a few seconds when your arm reaches its highest point. This is harder even at the same height as before, representing the stress that a distorted or clipped sound wave puts on an amp’s electronics or a speaker’s voice coil. If you aren’t careful, this added stress can overheat your amp or blow your speakers.

Questions To Ask Your Installer

Recklessly cranking up the gains isn’t a good idea, but how will you know if your installer sets them correctly to begin with? Here are some questions you can ask to make sure they know what they’re doing:

How do you plan on setting the gain controls?

Sometimes straight to the point is the best way to go. Answers involving matching the distortion point of the head unit and amp show your installer will be doing it right. An oscilloscope is a necessary piece of equipment to do the job right. Make sure they have one and know how to use it.

How loud can I turn it up without distortion?

The gain setting process involves matching the points where the head unit and amp begin to distort. Once the gains are set, your installer should be able to tell you where on the volume dial the distortion appears. You should never exceed this level. 

If I replace my head unit will the amp gains need to be reset?

Your installer should recommend the settings be checked when your head unit is replaced. Even if the output ratings are identical, there may be differences in the distortion point requiring a gain adjustment.

Extreme Audio Understands Gain Controls

You should now have a new appreciation for a properly tuned gain control, so go outside, crank up the tunes, and enjoy! If you don’t have an amplified system yet, well… What are you waiting for?

At Extreme Audio, we understand how to properly tune your system and set your gain controls. We have all the right equipment and we are extremely well versed in their uses. We invite you to stop in and allow us to show you around our facility. And if you are in the market for an audio upgrade… We can handle that too!