Rawmacias, first, if the cassettes you found are indeed RM encoded and not just incorrect album art, I am envious. I have the Yamaha MT44 four channel cassette deck that had Dolby B and C and pitch control. There was a mixer and a cabinet as well but I did not buy them. I bought it because I was thinking of transferring Dolby reels and playing back by cassette until I found a TEAC 4 channel Dolby unit. My understanding was that a 4 track cassette deck had the head gaps in slightly different places than a stereo cassette head made for auto reverse.