Jeroen Paul Thesseling
After his conservatory studies bass guitar in Enschede, the Netherlands, Jeroen Paul Thesseling (born April 13, 1971) recorded two microtonal pieces for 6-string bass. Further on into his career he started playing 7-string fretless basses that are tuned as follows: lowF#-26cts, B-20cts, E-16cts, A(440), D+12cts, G+22cts, highC+31cts.
'Discrepantium' - for 7-string bass 24tET (2013)
'Argon' - for 6-string bass 18tET (2000)
'Hafnium' - for 6-string bass 72tET (1999)