I bought a TranceAudio contact mic after hunting for a Frap & discovering that they are no longer made... i really like the TranceAudio - its sensitive & low noise & has a great frequency response (at least partly due to the perfectly matched contact mic & preamp) - lots of nice low frequency energy... My one is mono but I am considering buying the stereo version... When i bought mine I requested a longer cable between the contact mic & the preamp which has been handy, although you have to be careful as the cable is sensitive to handling noise...
FWIW there are some example recordings from my Trance Audio contact mic here:
the music of sound » fun with a contact mic..
plus some here from recording wind on aerial guy wires with it
the music of sound » capturing the wind (part 2)
its a VERY inspiring tool, it makes you look for sounds in the world in a different way, simply because it records structure borne vibration rather than in the air. Accordingly the recordings have no room acoustic!
