What happend to ultrasonic

[sausage fingers]

Does any one know what happen to ultrasonic pickups,i owned some ref 3s and they were awesome pickups.I remember seeing them in a bowling ball ando and i cant find them anywhere?

[tom]

they were made in germany. we used them before we made our own stacks. availability and reliability were issues for us. they also had a very dry tone, made for processing.