The Royer R-121 is a passive ribbon microphone with an innovative offset ribbon placement that gives the two sides of the microphone distinct features and sound.

The ribbon element is made of pure aluminum and is 2.5 microns thick, and is tuned to about 40Hz. It is offset toward the front side of the microphone case, which among other features provides a high-SPL capability of 135 dB on the front side. The rear side is equally sensitive but brighter (and less able to handle high SPL). Royer bills this feature as “two mics in one.” This innovation was patented in 1999.

The ribbon is 1.75 inches long, by 3/16ths (4.7mm) wide. The magnets, which define the active area of the ribbon, are 1.5 inches long.