Hello, Cameron!
Cameron Hall wrote to Herry Budiutama, 09 Aug 96 07:16:
 HB>> 1.  Dolby B
 CH> Gives 10dB noise reduction above 3Khz on a sliding scale upwards.
 HB>> 2.  Dolby C
 CH> Gives 20dB noise reduction more or less broad band.  (this is an
 CH> approximation)  Above a certain threshold compression and exansion
 CH> take place that doesn't take place in B type Dolby
Hm... I've always thought that Dolby B is a compression/expansion system,
too. Am I wrong? And whether Dolby C system is just a pair of Dolby B
systems, working in two different frequency bands?
 CH>  to add to the headroom and cut down on saturation of the tape at
 CH> higher recording levels.
 CH> The above two systems ABSOLUTLY REQUIRE that the tape be accuratly
 CH> calibrated to the machine in question to prevent losses during
 CH> record/playback.  Levels & EQ both must be precise.
One another question: I know that recording/playback channels must be
absolutely equal to prevent losses when using Dolby B and especially C.
But during using tape deck, heads (both recording and playback) are wearing
and loosing their perfomance. So the characteristics of recording/playback
channels would not be the same. I wonder, how much time would pass before
this effect take place? (I have AIWA ADF-850 deck with "super DX" heads).
                          With best regards, Vladimir
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