Audio Visuals were a group of fans who started making audio plays while the original series of Doctor Who was still running. The recordings were copied to cassette by the crew themselves and mailed out to people. They ran for 4 seasons from 1984-1991.
Many of the people involved went on to work at Big Finish Productions including John Ainsworth, Nigel Fairs, Gary Russell, Jim Mortimore and Nick Briggs (who played the Doctor from the second play onwards).
Some of the ideas from the Audio Visuals have also appeared in Big Finish plays, such as drudgers and the Temperons. Big Finish remade 5 of them – The Mutant Phase, Minuet in Hell, Vilgreth (as Last of the Titans), Sword of Orion and Cuddlesome. Additionally the play Frozen Time, whilst not a direct remake, was loosely based on Endurance.
Cuthbert, a recurring villain in the Audio Visuals and played by Barry Killerby, has been re-created in the 4th Doctor Adventures and played by David Warner.
Nigel Fairs went on to remake More than a Messiah as a BBV audio and video.
They can be seen, with hindsight, as the seeds from which Big Finish was sown, and where some of their major players learned their craft. Heavily experimental, they were often darker and more complex than the TV show as they were aimed at an older audience and, much like audios in general, at fans who wanted more depth in their stories. They also wrote stories to fit the audio format, unlike a lot of audios by others, including the BBC, which were more like an attempt to do TV on audio.
Thank you to Jim Mortimore for providing a link to download them all. As he worked on them this link is completely legal and you can download all of the plays freely. Enjoy.