Official Release #68. Originally Released: September 1998. All tracks produced by: FZ. Mystery Disc is a compilation album by Frank Zappa. It was released on CD in 1998, compiling tracks that were originally released on two separate vinyl records and included in the mail order Old Masters box sets, which were released in three volumes between 1985 and 1987. (These box sets, issued on Barking Pumpkin, contained repressings of Zappa's albums from Freak Out! (1966) to Zoot Allures (1976), along with a 'Mystery Disc' in boxes one and two.) The CD omits the last two tracks from the 1985 LP, "Why Don'tcha Do Me Right?" and "Big Leg Emma", both of which were included on the CD version of Absolutely Free (1967) in 1989.
Between 1985 and 1987, Frank Zappa released a pair of mail-order vinyl box sets called Old Masters that contained remastered and restored versions of all of his albums between Freak Out! and Zoot Allures. Each box contained an album of previously unreleased material called a "mystery disc." Although he eventually reworked and remixed a handful of these cuts for subsequent releases, the majority of these recordings were never again released in any form.
Originally released as two MYSTERY DISC LPs, first issued as bonus records to those who purchased Barking Pumpkins' OLD MASTERS vinyl boxed set in the mid-'80s. MYSTERY DISC includes early jams from Zappa's "Studio Z" days in Cucamonga, live performances by early Zappa bands, musical and spoken-word segments by a young Captain Beefheart, rehearsal sessions by the original Mothers Of Invention lineup and part of the score from the low-budget western Run Home Slow.