The Xcalibur JC was introduced in early 2018 in collaboration with Joe Chiccarelli, a Los Angeles based producer/engineer. He was checking out the original Xcalibur at his Sunset Studio in Hollywood and requested a few mods to make the unit more suitable for his way of work: A master pot replaces the 3-way attenuator switch, OD gain (marked OD+) now has 3 stages (mid/low/high), and there’s an additional 3-pos post-drive Low Pass filter (marked ODf2). All other functions and specs are the same as on the Xcalibur Standard. See manual for details.