They combined a dual amplifier with a matched pair of three-pattern capsules. The upper capsule could be rotated freely relative to the fixed, lower capsule and the amplifier. These microphones excelled at XY, "Blumlein" and MS stereo techniques. Because of the single-diaphragm construction of the capsules, the cardioid setting maintained its polar pattern down to the lowest frequencies − an important criterion for spacious-sounding stereo recordings. This quality is still unequaled by any other multi-pattern stereo microphone. The CMTS microphones were offered for 48-Volt phantom powering (CMTS 501) and for 12-Volt phantom powering (CMTS 301). The CMTS 501 continued well into the 1990s, and is still much appreciated today.