Stephan's wife, I believe, also makes instruments. Somewhere in the past I think I heard dulcimers mentioned. It may be that her work also bears the name "Sobell".
   And I second the opinion of Countess Richard above---Stephan was--likely still is---an accomplished entertainer in his own right. He was a regular at Hexham folk club 'way back in the sixties and seventies.
   And to those who would trace the "vanished" Stephan, make for Hexham, proceed to the "wilds of Northumberland" village of Whitley Chapel, and ask any resident for directions. Unless he has moved on somewhere, that's where you will find him.