In 1996, Mason founded the band SubArachnoid Space. Originally a trio, the band added second guitarist Melynda Jackson after the first 7" single was recorded but before the band's first show (on KFJC radio). After about 7 years and 9 albums, Mason left the group on good terms to concentrate on other projects and allow the band to tour more freely.

Mason performed with the band on the following releases (plus a number of compilation appearances):

  • Also Rising CD (2003)
  • Tigris ~ Euphrates LP (2002 split with Bardo Pond)
  • These Things Take Time CD (2000)
  • A New and Exact Map CD/LP (2000)
  • The Sleeping Sickness CD (1999)
  • Endless Renovation CD (1998)
  • Almost Invisible CD (1997)
  • Ether Or CD (1997)
  • Live at Ptomaine Temple cassette (1996)
  • Delicate Membrane CD (1996)
  • Char-Broiled Wonderland 7" (1996)