Miking Guitar Amps: Tips from Sound Pro John Mills
[Pointing to a Marshall amp] "This is a top that we use on stage … the numbers all go to 11 – right across the board. Most blokes are playing at 10 … but, where can you go from there? If we need that extra push over the cliff, we put it up to 11. One louder."
– Nigel Tufnel (Christopher Guest), in Spinal Tap
The electric guitar amp is a tricky little instrument. I say instrument because really good guitar players can make amps sing. There's nothing like a well-tweaked amp with a great guitar player plugged into it.
If you're like the rest of us, your amp only goes up to 10. So if you want to make your guitar amp louder (or one louder), here are a few tips that will help you to capture that sound.
The biggest tip for a good sound with only one mic is to place the mic right on the line between the dust cover and the speaker cone (Figure 1). This will give you a pretty tight sound that works best for everything from clean to distorted sounds.
The more you move a mic toward the center of the speaker, the brighter it will sound. On the other hand, the more you move it to the edge, the duller it will sound. If you have a player whose amp is pretty thin or too edgy-sounding, try moving more toward the edge of the cone to tame those highs.
My favorite thing to do is double mic an amp.
I use a Shure KSM27 condenser [Editor's Note: KSM27 is a discontinued model and has been replaced by model SM27 condenser] about 1 to 2 inches away from the line between the dust cover and speaker cone to get a good full sound. Then I place a Beta 56A on the other speaker right on the line. Both mics are about 1/2 inch from the grill cloth (Figure 2). I blend these two mics, kind of like a 2 band EQ, to make one sound for the amp.
This trick is useful from song to song thinking of one fader like bass and the other like treble. Instead of messing with the channel EQ to get the guitar to sit in just the right spot, try varying the blend of the two mic channels.
If you want to get really tricky, place a mic on the back of the cabinet (Figure 3). This is a very dull, but thick sounding spot, so you really need to blend it with a front mic to keep the detail. Don't forget to swap the polarity (the button that looks like a zero with a slash through it) on the rear mic. Otherwise you'll have a great deal of phase issues. This is another great sound that can really thicken up a thin-sounding amp.
About John Mills: John is a 20-year veteran of live sound. In addition to his work with touring acts, John is Vice President of Audio at Nashville's Morris Light & Sound and writes regularly for Worship Musician. He has been a longtime contributor to Shure Notes and is a featured speaker at many pro audio seminars across the country.