WHEN YOU HEAR A PHYSICAL GUITAR amp, you also hear the room—which can sound much like an EQ’d tapped delay with a gazillion taps. As a result, many amp sims emulate mic position, mic type, and where the amp is in the room to provide more realistic simulations. For example, choosing Cab in Pod Farm’s Amp View lets you place the selected cabinet in the room, and choose from four mic types with different positions. Native Instruments Guitar Rig 4 includes a Cabinets & Mics module with five different mic types and five different miking positions, as well as an Air control for mixing in ambience. Waves GTR offers 12 mics with various positions, and, with some amps, you also get a delay control to simulate space. Studio Devil VGA+ includes an ambience on/off switch and level control, and IK Multimedia AmpliTube 3 allows moving two mics around in a virtual space (Softube takes a similar approach with their cabinet simulation).
So which mic and position is optimum? Let your ears be the judge, but here are some guidelines to get you started.
DYNAMIC. A common miking choice for amps, with a relatively balanced response and solid lows. This works well for power.
CONDENSER. Generally brighter (like the difference between a single-coil and a humbucker pickup). Use this when you want definition.
RIBBON. The warmest (or darkest) sound—often with a lower midrange emphasis that sounds “creamy.”
ON AXIS. The mic points at the virtual speakers, which gives the fullest sound and smoothest midrange.
OFF AXIS. The mic points at the speakers from an angle, introducing peaks and valleys in the midrange, while thinning out the low and high end a bit.
Consider leaving ambience off for live performance as the room you play in will impart its own sonic characteristics (whether you want it to or not!). For recording, avoid adding ambience until other tracks have been cut. More ambience can make the guitar sit “further back” in the mix at low levels, or take over the stereo field at higher levels. I tend to use minimal ambience with rhythm guitar so the sound is more defined, but leads often benefit from some air. Of course, stacking two or more amps, with their own ambience and miking, opens up a whole other bunch of tonetinkering options. And isn’t that what amp sims are all about?