The idea of isolating a guitar amp is one alot of professional guitarists follow. But what’s the point of it? (In other words, my amp looks really cool, so why should I hide it so no one can see it???)
To answer, I’ll start off by talking about how an amp works. If you play through a good tube amp, you may know that you have two sections where volume affects your tone, the preamp and the power amp. As you increase the volume going through the first section, the preamp, you create overdrive. By increasing the master volume, (which controls your power amp) you increase the amount of volume coming out of the speaker. But as you do this, pay attention to your tone, because it will also change as the volume goes up. Most people would describe the sound as getting “warmer” or “fuller” as the volume increases. Some of this is due to the increased power through the tubes, and some of it results from more volume going through the speaker(s). Most guitarists agree that the more volume you run through your tube amp, the better your tone sounds. (Note: volume also affects the speakers in solid state and modeling amps, but the change may not be as noticeable as with a tube amp.)
But there is a catch. To get that good tone, you have to run your amp pretty loud, which is not practical for those of us who play in small to medium sized rooms. Many 15 watt tube amps can blow people out of the building. (Trust me, I’ve done it before) Even if you don’t think you’re running that loud, your amp can still cause problems in rooms with a lot of ambient reverb (like a room with concrete block walls). This happens because your sound bounces all over the place, and that natural reverb makes your band’s overall mix muddy.
The solution many guitarists use for this is to isolate their guitar amp, usually by placing it in another room adjacent to the stage. They’ll then put a mic in front of one of the speakers, (a Shure SM57 is a good choice), and run it to the sound board. This gives you two benefits: first it lets you turn up your amp as loud as you want to get good tone, and it also lets your sound guy control your volume level and eq in the house. (Note: happy sound guy equals less stress…)
If you don’t have a room near the stage, you still may have a few options. First, look for areas on or near the stage that are “more isolated” and mic your amp there. (Make sure it’s away from the general seating area.) If your speaker is within 10 feet of a wall or hard surface, you may want to put some foam, blankets, carpet sections or pillows a few feet in front of your speaker to help absorb the sound. If all else fails, try positioning your amp near the back of the stage, turn it backwards or sideways, and mic it. Then look for anything you can to place around it to absorb the sound.
If you use your amp as a monitor, isolating may take some getting used to. Stick with it though. As frustrating as it may be at first, it will ultimately give your band a better sound.