Dolby HX Pro
Dolby HX Pro adjusts recording bias as the music changes, helping magnetic tape handle strong high-frequency signals.
It operates during recording and requires no matching HX Pro decoder during playback. It is separate from Dolby noise reduction, which encodes and decodes the audio to reduce tape hiss.
Dolby HX Pro — Cassette Deck
HX Pro responds to the high-frequency content of the signal being recorded. Those frequencies contribute to the tape's effective bias, so the system reduces the applied bias when necessary. This helps preserve treble headroom rather than letting strong high frequencies over-bias the tape.
Compare HX Pro availability separately from Dolby B, C or S noise reduction and from automatic tape calibration. A recording made with HX Pro can benefit on a player without it; any noise reduction used still needs the appropriate playback setting. HX Pro does not remove hiss from an existing recording.