“I recently picked up a Royer R-121 ribbon mic for acoustic guitar, which it sounds great on. I’ve heard that they also sound good on electric guitar amps, but in trying it I’m finding it too bass heavy. Any ideas?”
Well, the easy answer is always, try another mic. The second easy answer is to move it around, which is closer to the point.
The bass response of most ribbon microphones on guitar cabinets will tend to be much better than that of most dynamic microphones. Traditional ribbon microphones can be damaged if you position them too close to an extremely loud guitar cabinet. Most experienced engineers know this and position ribbon mics accordingly. Royer’s R-121 and R-122 mics were designed to take high SPL‘s and can handle reasonably close miking duties on a loud guitar cabinet. But that doesn’t mean you should use them up close…
Cabinets develop more of their bass resonance as you move further away from them, so an R-121 placed one, two, three, even six feet back can give you the bass response you’re looking for. Ribbons have a strong proximity effect, so placing a ribbon mic any closer than 4 inches from the cabinet grill cloth will result in a “bass-heavy” sound. While that might be too thick a sound for a guitar track for most engineers, it can still be a useful effect for others. Some engineers put an R-121 close on a cabinet, then blend an SM-57 for the aggressive top end. Blending the two mics carefully can give you the 57’s crispy top, and the close R-121’s exaggerated bottom, for a huge rock tone. Try that or simply moving the mic back a couple of feet. This wouldn’t help you with most mics, but in this case you may be surprised at the results. The low end will likely be tighter and better defined.