The Secrets of Multi-Mic’ing
May 17, 2011
Mic’ing a speaker from the rear of an open-back cab can yield extra low-end booty. In this configuration, an AKG D 3500—a dynamic often used for kick drums—is positioned behind an early-’80s Fender Super Champ equipped with a Kenrick 10". Photo by Andy Ellis
Mic’ing up a guitar amplifier and getting great tone can be very easy—just jam a Shure SM57 up to your amp’s speaker cone, right? Don’t get me wrong, but there’s more to a tone-filled life than that! There’s a reason the SM57 is the standard—it always works. But why not open your mind and explore some other options, especially in the studio?
In last month’s column (“Going the Distance,” May 2011 PG), we talked about mic’ing up the studio room to achieve a more open and ambient sound. We also discussed the advantages of combining one mic (like the trusty SM57) close up on the amplifier with a second condenser or ribbon mic placed further away. We saw how you could set the latter to an omni or figure-8 pickup pattern to capture room tones, and also learned how to minimize phase cancellation.
We’ve discussed most of these microphone terms in past columns. If you need to refresh your memory, or missed any of the columns the first time around, they’re available 24/7 at premierguitar.com.
But we’re not done yet: There are several things you can try to expand your microphone horizons even further, and that’s what we’ll explore right now.
If one is good, two are better. One microphone positioned away from the amp will give you a nice ambience to blend in with the dry amp sound captured from the close mic. Taking it to the next level, try using two room mics with space between them. Depending on the size of the room, set up the mics at ear height 6' to 10' from the amp, and 6' to 10' apart. Record your close mic to one track and the two room mics to separate tracks. Pan the close mic to the center, and pan the two room mics hard left and hard right. Voilà—instant depth, space, and perspective! Using EQ to tweak the sounds from the two room mics, you can emphasize the room characteristics you want to blend in with your dry sound.
You can really go crazy experimenting with room mics. A mic placed close to the wall will have a bassier sound. Try one in a corner where two walls meet, and you’ll most likely get an even bassier sound. Position one in a trihedral corner, where two walls meet the ceiling, and you could get a really cool tone to add in with your dry sound or blend with your stereo room mics (though you run the risk of a sound that may be too bassy or boomy with that mic position). Record this mic to a separate track and mix it in to taste.
If one is good, two are better ... take two. Knowing it can be difficult to get everything you want from just one mic, let’s shift our attention to the close mic. One idea is to position a second close mic on the amplifier. If the amp has only one speaker, you will need to find a spot where the second mic sounds good and complements the first. This may be as close as possible to the first mic, or it might be an entirely different position on the speaker.
When placing the second close mic right beside the first, position the second mic at a 45-degree angle to the first. This method will work best if the two mics are the same model because the second mic will pick up the sound off-axis and deliver a different tone from the first.
With other scenarios using two close mics, you’ll probably want to try a different second mic for more options when mixing. You could combine a dynamic as your first mic and a ribbon as the second, or try a dynamic and a condenser. Maybe a condenser and a ribbon will do the trick for you. The key is choosing the first mic for the basic tone you want, and then matching it with a second mic that will fill what’s lacking. If the amp has more than one speaker, positioning the second mic on a different speaker may give you more tonal options. Again, try using the same model mic for both or test out different models for a more diverse tone.
No matter where your second close mic is placed, remember to record it to a separate track so you can balance it with your first close mic. You can pan them both to the center, slightly pan left and right for more depth, or hard pan left and right for a wide sound.
Relocate. There are other places a second close mic can go—it doesn’t have to be jammed into the speaker like the first one. If you have an open-back cabinet, try placing the second mic at the back of the cabinet and mic the speaker from there. You’ll achieve a very different sound from the mic on the front. There is one caveat in this scenario: You’ll need to flip the second mic’s polarity to 180 degrees out of phase, or it will suffer from phase cancellation with the front mic.
Then we have the “3:1 Rule of Mic Placement,” which we covered last month. This method involves positioning the second mic three times the distance from the first mic as the first is from the source. So if mic A is 2" from the speaker cone, place mic B 6" back from mic A. Record the two mics to separate tracks, then blend to taste along with room mics, if desired.
There are tons of options for mic’ing up an amp when using more than one mic. Spend some time experimenting—better recorded tone awaits!
Mitch Gallagher is the former editor in chief of EQ magazine. He’s written more than 1000 articles and six books on recording and music technology, and has released an instructional DVD on mastering. His upcoming book is entitled Guitar Tone: Pursuing the Ultimate Electric Guitar Sound. To learn more, visit mitchgallagher.com.