Jon Mroz & His Bull Fiddle Four is a Milwaukee-based post-war electric blues combo featuring Jon Mroz on upright bass and vocals.

Mroz, known for leading the Swingin’ Kools in the 1990s and the early jazz band Troubadours of Rhythm today, assembled his Bull Fiddle Four to celebrate the raw energy and pioneering sound of late 1940s and early 1950s blues legends like Muddy Waters, Jimmy Rogers, and Little Walter.

The lineup features some of the Midwest’s most accomplished musicians:

Big Al Dorn, Wisconsin’s premier harmonica talent (2025 WAMI winner!) and a protégé of blues icon Jim Liban.

Paul Stilin, a veteran guitarist with a storied career in Milwaukee’s blues and jazz scenes.

Tael Estremera, a multi-instrumentalist whose virtuosic piano playing adds a rich dimension to the band’s sound.

Patrick Morrow, a powerhouse drummer of taste who has toured with roots acts across the country.