Mellotronists

recently listening to Jan Hammer's excellent FIRST SEVEN DAYS 
remaster,Pete Sinfield's STILL,and PFM's PHOTOS OF GHOSTS(River Of 
Life),I am still moved by the great string sound achieved by the 
Freeman.I know Jan Hammer ran his through a Moog String Filter 
box,but I recall playing one in a store that didn't sound anywhere as 
good as what I heard on record.I remember reading somewhere that the 
production units differed in some aspects from the prototype that Ken 
Freeman made.Anyone have knowledge of this?
 I always thought that this unit's string sound was way beyond the 
ARP string ensemble or Elkas or whatever.It would be nice to have 
some samples of it...