Eric Seaberg;313567 Wrote: > BTW, Dolby 'A' or 'SR', which was designed for professional use, is > TOTALLY inaudible when setup properly. Dolby 'B', the consumer > 'cassette' noise reduction scheme, is VERY audible because the > record/playback levels were never matched for proper compansion. The > 'other' system you may have been thinking of was DBX, which didn't have > the 'level-setting' requirements that Dolby did. > >
Sorry Eric, I'm with Pat here. There hasn't been a Dolby NR recording of a Female choir that I haven't heard the Dolby pumping in and out on the trebles producing a kind of modulation over the voices. I used to think it was the microphones until one day I had the opportunity to do a recording myself with and without Dolby A. Switch off the Dolby and the effect disappeared. It's very slight but audiable and the same effect is there but much more exagerated with Dolby B. If you really want to hear it try Dolby C. Actually you can measure it. Effectively the Dolby adjusts the high frequency response of the recording and playback according to the content of the recording. If there are no treble sounds present then you can turn down the frequency response of the recording chain to loose the noise, as soon as high frequency appears you restore the equalisation using the recorded sound to mask the noise. Unfortunately the spectrum of the noise doesn't exactly match the spectrum of the material and with some material it appears to cause some type of intermodulation which is audiable. Put a frequency analyser on the output and it is possible to just see it. The only advantage of Dolby A was to split the audio spectrum into 3 bands and deal with each band seperately which made it essential to align the equipment properly before recording. But is was still annoying once you noticed it was there. Fortunately this particular problem disappeared when we entered the era of digital mastering. Strangely enough I have heard a similar effect happen during demonstrations of "Audio Watermarking." This time it seemed to produce an extra "edginess" to the Brass instruments. Enough to be able to do a blind test as long as there was some brass content in the recording. That was a few years ago, they may have fixed it by now as I haven't heard it on any broadcasts. -- MrStan ------------------------------------------------------------------------ MrStan's Profile: http://forums.slimdevices.com/member.php?userid=1771 View this thread: http://forums.slimdevices.com/showthread.php?t=48748 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
