Jeroen proudly endorses WARWICK basses and plays Thumb NT series exclusively since 1993. He has played several Thumb NT6 and NT7 basses, each marking different chapters of his musical career. During PESTILENCE's 'Spheres' era he started playing Thumb NT6 basses. From 2005 and later on recording OBSCURA's second and third full-length albums 'Cosmogenesis' (2009) and 'Omnivium' (2011) he played exclusively fretless Thumb NT6 basses. Since 2011 he plays fretless Thumb NT7 basses, master-built by WARWICK's custom shop in Germany.

Tuning: F#(0); B(0); E(1); A(1); D(2); G(2); C(3); Strings: WARWICK Black Label - medium stainless steel round wound; String gauges: .175; .135; .105; .085; .065; .045; .025; Pickups: Bartolini 7-string P4 soapbar XXP47C; Electronics: Bartolini NTMB, Bartolini EZQ; Outboard gear: TC Electronic SCF stereo chorus, Phoenix Audio DRS-Q4 MKII dual channel preamps; Kush Audio Electra - dual channel electrified transient equalizer