Tech Tip:Guitar Miking: Getting a Great Guitar Sound, Part 2
Figure 1 shows a Shure KSM44 condenser about 20" from a 1960s-vintage Marshall 4x10 cab. (I was auditioning the three cabinets in the picture.) With this setup, the guitarist might complain that his amp sounds brighter than usual, especially compared to a SM57, and feel he must readjust his amp's settings.
Fig. 1: Cabinet Miking
Condensers also pick up more low frequencies from the amp than dynamic mics. This may or may not be a good thing; pushing a lot of air might work in a heavy metal track, but can be inappropriate for a lighter pop song. Certain condensers can overload when close-miking extremely loud amps. Occasionally, the mic's metal windscreen can get loose and vibrate. Always use the attenuator pad and, if necessary, the low frequency roll-off. The Neumann U-87 and U-47FET, Shure KSM44, or the Audio-Technica AT-4041 are all good choices.
Many condenser mics also offer an opportunity to experiment with different polar patterns, such as omni-directional and figure-8. Omni mics differ from cardioids in that they do not exhibit proximity effect. Omnis, which receive signal from all around the capsule, pick up more of the total sound of the amp and room tone (as opposed to the cardioid sound, which focuses on the source in front of it). This makes the omni pattern a good choice for ambient guitar sounds and, when used in a multi-mic setup, as room mics. Figure-8 mics also pick up more of the room than cardioid mics, receiving signal at the front and back of the capsule.
Royer R-121 Ribbon Microphone
Like other figure-8 mics, the Royer picks up sound from two opposing sides in what is also called a bidirectional pattern, and you can take advantage of this to get more of the recording space or room in the sound. (Experts note: The sound entering the rear of the mic is 180 degrees out-of-phase with that coming into the front.)
When A/Bing the Royer against the SM57, one engineer remarked to me, "When you switch from the Royer back to the 57, you wonder where half the guitar sound went." While a big, fat, and warm guitar sound like the one described here might sound ideal on its own, make sure it fits your mix before you commit to it.