Ribbon Mic Resources
There are now several choices for good ribbon microphones in current production. For many years the only available types were the Beyer products, including some excellent hypercardioid designs, and the Coles, which are made under license from ST&C which made them for the BBC. Coles are imported and sold in the US by Wes Dooley in Pasadena, near Los Angeles. Wes also repairs the Coles mics, which require a much thinner ribbon material than is commonly available in the US -- 0.6 micrometers thick. If your Coles has no bass, it was probably re-ribboned with thicker material.
New on the scene are the Royer mics, which are derivative of the 1960's Danish B&O mics, with some of the improvements incorporated in the Speiden designs, and the AEA (Wes Dooley) R44 series, which is a very close copy of the RCA 44BX.
Two reputable repair outfits for re-ribboning RCA and Western Electric ribbon mics are Clarence Kane of ENAK in New Jersey, phone 856-589-6186, and Charlie Gant in southern California. Charlie has apparently retired, but Clarence is still available and also does B&O ribbons. For Shure ribbons suggest you contact Dick Gardiner 612-458-1193 .
No warranty expressed or implied with this information. I have
personally dealt with Gant, and have seen Kane's work. Both performed as claimed. The critical thing to check with anyone doing repair to a ribbon mic is to be sure the resonant frequency is set correctly; incorrect tension
or incorrect ribbon thickness (almost always too tight, or too thick) will
result in (almost always) too high a resonant frequency. The RCA 44
series should be 20-25 Hz, the 77 series and the Coles around 40-45 Hz.