In a previous discussion we talked about how the advent of the master volume control in guitar amps allowed for channel switching to be utilized. Today we will look at how distortion can be created and controlled when the amp is switched to the lead or "gain" channel.
As we observed earlier, the "master" volume control allows you to adjust the overall volume of both the clean and distortion channels of the amp.
Within each of those channels are various controls that enable you to set and tweak the sound, tone and volume of that particular channel.
On most amps, the lead (or gain) channel is the one you will use to produce distortion. In addition to tone adjustment controls (bass, mids and highs) there will typically be a control that is labeled "gain", "boost" or "drive".
Furthermore, many times there will be an additional level control for the lead channel that works in conjunction with the "gain" control.
Knowing how to set these controls will give you the ability to "dial in" just the right amount of distortion for your tastes.
If you have a "gain" control, and a volume or level control within the lead channel of your amp, it's important to know the difference between the two.
The "gain" (boost or drive) control is used to adjust the "amount" of distortion.
The volume control is used to adjust the output "level" of that distortion.
Increasing the level of the "gain" control raises the saturation, resulting in "over-driving" the sound, which causes distortion.
Simply put, if you want more distortion, turn up the "gain" control until you reach the desired amount of overdrive.
Once you've found "the zone" on your distortion, then make adjustments to the volume for the overall output level.
If your amp only has a "gain", "boost" or "drive" control, but no volume control for the lead channel, you can make the same adjustments, only using the amps "master volume" control.
As before, adjust the "gain" control for the desired amount of distortion - then adjust the master volume for the overall output level of the amp.
This theory also works in reverse. If you are experiencing too much distortion, or your sound is "breaking up" more than desired - try turning your "channel" volume down, and your "master" volume control up. This will result in a "cleaner" sound.
By fully understanding that the "gain/boost/drive" control is where you dial in the "amount" of distortion you want - and the "volume" control is used to adjust the output "level" - you will be able to tweak the sound of your guitar amp like a pro!
