Dolby Dolby, analog and digital sound up to 6.1, not encoded as true 6.1, but a mix from 5.1, surround center back is matrixed into the surround left and right channels called Dolby Digital 5.1 EX (the earlier called AC-3, is Dolby Digital up to 5.1). Others from Dolby are (analog formats) Dolby pro Logic (4.0), Dolby pro Logic II (5.1), Dolby pro Logic IIx (7.1), mix from stereo etc. Visit Dolby Back To Technical Main E-mail us with your favourite products etc and we will add it to our site/archive..