A handful of Prince's unreleased recordings are totally fair game as far the producer is concerned, because he says he never signed a contract to keep the music under wraps.

George Ian Boxill, the former sound engineer who briefly released the "Deliverance" EP last month -- before Prince's estate blocked it -- filed new legal docs saying his deal with Prince was strictly for remodeling his studio.

Boxill says he helped overhaul Prince's studio in 2004 and did indeed sign a nondisclosure agreement. He insists that document ONLY applied to that job. Later, Boxill served as sound engineer when Prince recorded the 5 tracks on "Deliverance."

According to the docs, Boxill never signed a nondisclosure for the recording sessions.

He's asking the judge to throw out the estate's lawsuit which is blocking him from releasing the music to the public.