Complex sentence: Mark Wirtz is an Alsatian born producer of pop records, his most famous output being from the mid to late 1960s, when he worked at Abbey Road Studios under contract to EMI alongside the Beatles engineer Geoff Emerick.
Split into simpler sentences: Mark Wirtz is an Alsatian born producer of pop records. His most famous output being from the mid to late 1960s, when he worked at Abbey Road Studios under contract to EMI alongside the Beatles engineer Geoff Emerick.