The Groove Tubes MD1B-FET is a class A FET (field effect transistor) microphone that is a large diaphragm condenser microphone. It is a reissue of the Groove Tubes MD1. It has a frequency response ranging from 20 Hz to 18 kHz and will pick up sound in a traditional cardioid polar pick up pattern. Groove Tubes isn't necessarily known for making microphones, but rather for their line of tubes. I've only used the MD1B-FET in the recording studio, and wouldn't recommend using it anywhere else as FET based mics are meant for use in the studio only.
Overall, the Groove Tubes MD1B-FET definitely has a unique look and design. I'm really most concerned with the way it sounds, which is also somewhat unique for a modern microphone. Since it is designed after a vintage microphone, it definitely does contain more than average warmth from a modern made microphone. I've only used the microphone on two sessions with the same singer for recording vocals in a home studio that was not my own. Even though I haven't used the original MD 1, in general it seems as if modern reissues of classic microphones don't always sound the same. I'm not saying that this is the case here, but in my experience this seems to be the case, although of course there are exceptions. One reason for this could be that I feel more companies today are cost conscious with their gear since they want to appeal to home studio owners on a budget as well as professionals. That does seem to be the case with the MD1B-FET, as the price was very reasonable when it was being made. Since it is discontinued I'm sure that you can find them for even cheaper now as well. For a microphone from an unlikely source and at this price, the Groove Tubes MD1B-FET is a very good sounding microphone that would be a great fit for any home studio owner looking to add a FET based mic to their collection for some diversity.