After you’ve spent all this time making sure you have the right amp, guitar, pickups, cables, and pedals, you’ll want to make sure it makes it out of the PA the way you want it to sound too. It would be a waste to spend all that energy and money building a guitar rig, only to have a mic slapped in front of your amp and fighting against the tone you are going for.
The mic is responsible for conveying the punch of your speaker and the brightness or darkness of your sound. Here are the steps and principles to micing an amp:
#1 Find your speaker
You need to locate exactly where the center and edge of the speaker in your cab. You may have to use a flashlight directly on the grill cloth to see exactly where your speaker is. Once you do, you need to know the parts of the speaker. The center is called the dust cap (which covers the voice coil). The edge of the speaker is called the surround. The speaker cone is located in the area between the dust cap and surround.
#2 Find your Mic
The most common mic you see used is a SM57. This mic has been used for live and recording forever. This mic uses the exact same capsule as its counterpart the SM58. The main difference between the two is that the SM57 has a shorter grill which allows you to have a closer proximity to what you are micing. The SM57 is a rugged mic that will be a total workhorse to have in your arsenal.
The mic I prefer is the Sennheiser E609. Like the SM57 it can handle loud amps well without causing the mic to distort. It has an increased frequency response from the SM57 (E609 – 40hz to 18khz vs SM57 – 40hz to 15khz). The increased frequency response gives you more brightness and clarity, which is something you may or may not want.
The MD421 is an amazing mic to use on your speaker. It also pairs very well with the SM57 or E609. The MD421 is characterized by being brighter mic, but with balanced lows .
#3 Know where to place the mic
This is an intense topic, and has been full chapters in books. But I am going to try to explain it in a few simple steps.
Your mic should be placed about 1 inch from the speaker. Putting the mic on the grill cloth gets you pretty close to being an inch away.
There are a few principles to understand about mic placement in relation to your speaker.
- Closer to the Dust Cap: Pointing the mic closer to the dust cap is BRIGHTER
- Closer to the Surround: Pointing the mic closer to the surround is DARKER
- Moving the mic away from the speaker causes you to hear more ambience and room sound, closer is best for live performance where you do not want the ambience from a noisy stage.
- On Axis – Pointing the mic straight at the speaker.
- Off Axis – Angling the mic inwards towards the dust cap. This is used to mic near surround or middle of the cone, but point inwards. It allows for a full sound as you get the darkness of being near the surround, but blends with the brightness of the dust cap.
The reason I want you to know these things is that you don’t work against yourself. What I mean is this:
My Guitar is too bright, so I darken it in with my tone knob and eq on my pedalboard. But now I turn up my treble on my amp and then mic it close to the dust cap and end up with a brighter sound. Now I ask the sound guy to roll off a bit of the highs. We just added and removed frequencies 5 times, when we might have been able to solve your brightness problem by rolling off a bit of the treble on the amp and then micing closer to the surround.