Since the dawn of time, engineers have struggled with the task of getting good guitar sounds on stage. One of the big issues is stage volume: the musician cranks it up to get “their sound” while the engineer and audience get blasted with ear-crushing levels from the stage. Inevitably, the PA has to be cranked up to overcome the stage volume. Let’s assume, for the moment, that the musicians you work with have their stage volume under control (whether it be via volume knob, moving cabinets off-stage, or threats of violence) so that you can actually hear the guitar through the PA and create a mix. There are some tried-and-true methods you can use to get great guitar tones.
Guitar Amps
Before we look at specific mic techniques, let’s quickly revisit the nature of the typical electric guitar rig. A guitar amp produces sound through a paper cone, and the result is not what one would consider “high fidelity.” In fact, most guitar amps don’t produce much above 5 kHz, so using that $7,000 tube condenser mic is likely to be a bit of a waste(!). It might be to your advantage to use a microphone that does not have an extended high-frequency response, because that could make leakage from the rest of the stage more pronounced.
The most basic technique employs a single directional microphone placed close-up on one speaker. Microphone placement is critical for live sound, because pulling the mic back to a point where it captures a blend of all of the speakers in the cabinet would result in a din of unwanted sound bleeding into the guitar mic from the rest of the stage (also a reason to avoid omni-directional mics in this application). In situations where the cabinet has two or four speakers, it’s worth trying the mic on each speaker to determine which one sounds best — and, trust me, they won’t all sound the same.
Get Yer Free EQ
The center of the cone (the “dustcap”) usually produces the brightest sound. As you move the mic away from the center and toward the outside edge of the cone, the sound will mellow out. Ditto for pointing the mic off-axis. Any position will be brightest when the mic is pointing straight at the speaker, so you can really tame an aggressive sound by moving the mic to the edge of the cone and turning it 30 to 45 degrees off-axis, away from the dust cap.
Most directional microphones exhibit proximity effect, so jamming the mic up against the speaker grill will deliver a bass boost that could make the amp sound muddy. Some microphones produce more exaggerated proximity effect, so experimentation with placement is in order. If you really need to get the mic close and find that the sound is getting bloated, use that high-pass filter we discussed in November’s T&P! (FRONT of HOUSE, Nov. 2011, page 41).
Likely candidates for miking a guitar amp include the Shure SM57, Audix i5 and D3, Sennheiser MD421, MD609 (and MD409, if you can get one without taking a second mortgage). Not-so-likely candidates include the AKG D112 (yeah, it’s a kick drum mic, but it sounds excellent on guitar), Electro-Voice RE20 and RE320. For Buck’s rig in Blue Öyster Cult (Buck uses Steinberger guitars, an Engl 530 preamp, Crate and Marshall amplification), my favorites are the SM57 and Audix D3 (which, alas, has been discontinued). For clean electric guitar, a ribbon mic (Royer R-121, Shure KSM313, Audio-Technica AT4080 or AT4081) can be a wonderful thing. Before you freak out over the fact that these mics are bidirectional, remember that you are placing the mic close to the cabinet, and the null of the figure-8 will be aimed at neighboring sound sources producing the most leakage. You can increase isolation further by using a baffle in front of the amp, which also helps control stage volume.
Multiple Mics
There are at least two philosophies when it comes to using multiple microphones on a single guitar amp. When the guitar rig is stereo, it makes sense to mic the left and right sides using the same brand and model of microphone. Route them to adjacent channels on the console and (if you are using a digital console) pair them so you can EQ, compress, and adjust their faders concurrently. I typically pan the mics hard left and right, but in situations where I feel like the guitar is not present enough, I’ll tighten up the pan controls, helping push them forward in the mix.
Another reason for using multiple microphones on the same cabinet is to get the sonic variety provided by different microphones. Some engineers combine the mics, balancing them as a means of EQ and using both mics in the mix at all times for different textures. (You may need an assistant to move one or both mics around the amp as you listen through the PA). Other engineers will set one mic for the rhythm sound and use the other mic (usually the brighter one) to emphasize the lead sound, pushing up the lead mic in the mix when the guitar player takes a solo. One interesting technique is panning the brighter, or “harder” of the two microphones toward the lead guitarist’s side of the stage, helping solidify imaging in the mix.
Personally, I find that the phase issues and comb filtering created by multi-miking are more trouble than they are worth, but your mileage may vary. In cases where a guitar player switches between distinct sounds (e.g., clean and distorted) you could use a specific mic for each sound, switching the channels on and off depending upon what the guitarist is playing.
In addition to the high-pass filter mentioned earlier, low-pass filters can help minimize some of the effects of leakage or take the edge off a harsh sound. Ditto for EQ: judicious cuts in the 3 to 4 kHz range help smooth out the tone, while cuts in the 200 to 300 Hz region make room for the snare drum and reduce clutter in situations where a band has multiple guitarists.
Effects
Guitar players are very picky about their effects (rightfully so), and many prefer to handle their own. On occasion, I’ll add a bit of echo to a solo: 250 to 300 mS, no more than two repeats, with fairly heavy high-pass and low-pass filtering, so that the delay does not step on the main sound. I usually leave reverb to the player, but sometimes, when a band is performing outdoors, a touch of reverb helps make the guitar sound more natural and adds depth. I like a few dB of compression on the guitar channels with a low ratio (2.5:1 or 3:1), medium attack (30 to 50mS) and release (70 to 100 mS). Set the threshold so that the compressor digs in 3 or 4 dB when the guitar player gets loud. Over-compressing the guitar will rob the performer’s dynamics and may cause the sound to become dull. Some engineers assign all of the guitar channels to a VCA group (analog console) or a DCA group (digital console) to facilitate mixing a lot of guitar channels. If you find that the overall balance of guitars is high relative to the rest of the band, one group fader movement can pull many guitar channels down without destroying the balance between multiple mics on a rig or disturbing the balance between the various players.
The ideas mentioned are battlefield-tested, but should serve only as a starting point. As with most things audio, there are no rules — a small investment in time can yield great sonic discoveries. I’ve even heard of engineers placing boundary mics inside the rear of open-back amps. Here’s wishing you good audio and success in 2012!
A Quick Word About Stage Volume
When dealing with loud guitars in small rooms, there are a couple of things you can do to manage the SPL. One thing that I have had success with is turning the speaker cabinet backward so that it faces upstage. It looks a little weird, because the audience might be looking at the rear of the cabinet, but keeps the cab from blowing into the audience. Another approach is placing the cabinet off stage. Over the past several months with Blue Öyster Cult we have moved Don “Buck Dharma” Roeser’s guitar cab offstage. We set the backline as normal with Don’s 4×12 facing the audience during soundcheck. He used this cabinet to set his rig and dial in his sound. Once Don is happy with his settings, we disconnect this cabinet and connect a remote cabinet. On large stages, we simply place the cabinet way upstage, but in small rooms, we have been able to find a closet or some small room backstage for the cabinet. Since 90 percent of the dates we do are fly-ins, we don’t have the luxury of traveling with full production. But another alternative would be to place the cabinet inside an isolation box, or to travel with one of the many available iso cabinets.
