Wayne Parham Messages: 18783 Registered: January 2001
Illuminati (33rd Degree)
Dolby B is really just treble pre-emphasis with automatic gain control. I've noticed a lot of store bought tapes from the seventies were so cheap they didn't have much HF extension, so the pre-emphasis was lost. My suggestion is to test them by ear, because even if you know a tape was recorded with Dolby B, if the tape doesn't have much on it above 10kHz, I don't think I'd want the Dolby B decoder to take away what little was left.