From media@pcnet.comTue Jun 27 16:17:36 1995 Date: Tue, 27 Jun 1995 18:56:59 -0400 (EDT) From: Machine Media To: SKstokes@aol.com Cc: electronica@andrew.cmu.edu Subject: Re: Dolby > Would anyone be so kind as to a short refresher on Dolby noise reduction. > What exactly is Dolby NR (B and C), HX PRO ect. OK, this is real short because I hate Dolby!! Dolby A -- An old noise reduction system for reel-to-reels Dolby B -- The "classic" Dolby on cassette decks, it boosts the highs during recording, and attenuates them during playback to cover tape noise. Dolby C -- Same as Dolby B except that they realized boosting the highs increased tape saturation, so they added a dip at 10K during recording, so you can record louder, and a 10K boost at playback. Impo, only works OK if the playback & recording decks are calibrated to each other or the exact same machine!! Dolby SR - "Spectral Recording" the latest pro dolby. Used on multitrack and half-track systems. Alot better than A, B or C and also alot more expensive. Some people swear by it. HX Pro - Despite it's name, most often found on consumer cassette decks. However it it also found on pro cassette decks and cassette duplicating systems. The good thing about HX Pro is that it is a single ended system -- you don't need HX Pro on the playback deck. It works by tweaking the bias in relation to the program's low end content -- hence boosting the maximum recording level, thereby increasing S/N. PEACE OUT :) MARK