The Groove Tubes Model 3 is a somewhat rare tube microphone. Aspen Pittman designed it as a “no compromise” replacement for the C-37A. It has a Josephson capsule, similar to one they now use in the Manley Reference Silver and their own C715 microphone. Aspen made a lot of high end studio equipment that was beautifully designed and innovative but in my opinion likely suffered commercially from the somewhat silly company name. None the less, the Model 1, Model 2, Model 3 are all sleepers on the used market.