Jelte Althuis (1967) studied clarinet under Herman Braune and George Pieterson at the Sweelinck Conservatory in Amsterdam, qualifying as a performing musician in 1993. He concluded his simultaneous bass clarinet studies under Harry Sparnaay with distinction. Since joining Calefax in 1994, he has been both a member and arranger, playing regularly for the larger orchestras in the Netherlands. At Calefax, he usually limits himself to playing bass clarinet and basset horn. Jelte owns, maintains and drives a 1969 Volvo Amazon.