Hey Charlie, would you like to add or simplify what I found below in a thread -

My main question arose when I would come across two camps of how Ultra-Matrix tapes were made; first, I think it is widely known that Healy recorded the FOH Sbd feed through a delay to a Sony PCM-F1 for A/D then to the video heads of a Beta HIFI recorder; at the same time recorded an AUD feed from FOB mics [anyone know that setup or have pics?] and that analog feed got sent the audio heads of that Beta HIFI machine [does anyone know the model he used?]. So now Healy has a PCM FOH sbd recording, and an analog AUD tape recording timed up because the FOH sbd feed was delayed to match the AUD feed to the tape. Many people say he would then mix the two 2-track recordings to a cassette tape, sometime after the show, and viola we have an Ultra-Matrix tape.

Next came the question of all the master cassettes of these Ultra-Matrix shows, did Healy do that many of them in the hotel room after the show or sometime after the tour and get them out there? Does every Ultra-Matrix tape come from a mix off of the Beta HIFI machine? I believe there are shows you can get/hear separately the PCM FOH Sbd, the AUD feed, as well as the Ultra-Matrix master cassette— I don’t know any off the top of my head, but I am sure some here know— but that does not really answer the question of just how the cassette master was made.

So continuing on I notice some comments Charlie Miller made in an etree post trying to explain things to someone, placed here slightly out of order:

“I didn't label the board tapes as matrix since the Healy UltraMatrix was what was used for board tapes from Spring 87 through 12/31/90. So if you see a sbd tape from that era (plus a few Dec 86 shows), then it's a matrix made by Healy.”