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- From: larry@csccat.cs.com (Larry Spence)
- Newsgroups: rec.audio
- Subject: Re: Sony's SBM CD Mastering
- Message-ID: <1992Jul30.213321.16632@csccat.cs.com>
- Date: 30 Jul 92 21:33:21 GMT
- References: <1992Jul28.145411.180881@cs.cmu.edu> <1992Jul28.221729.13569@cbnewse.cb.att.com> <1992Jul29.235552.18085@ntg.com>
- Organization: Computer Support Corporation, Dallas,Texas
- Lines: 34
-
- In article <1992Jul29.235552.18085@ntg.com> dplatt@ntg.com (Dave Platt) writes:
- >In article <1992Jul28.221729.13569@cbnewse.cb.att.com> acgd@cbnewse.cb.att.com (andrew.charles) writes:
- >
- >>I saw the same article. I took it to mean that Sony has found a better way
- >>of dithering. "20 bit resolution" is pure marketing nonsense. 16 bits is
- >>still 16 bits.
- >>
- >>This doesn't imply that SBM won't improve the sound of discs. From what I've
- >>read, dithering makes a tremendous difference and an improved algorithm
- >>may be very effective.
- >
- >As I understand it (based on an article in the current issue of Audio),
- >the SBM technique is basically a noise-shaping technique. It shifts the
- >spectrum of the quantization noise (produced during the 20->16 bit
- >truncation) so that it's concentrated at frequencies at which the human
- >ear is less sensitive. The total amount of quantization-noise energy
- >isn't reduced, but its impact on our ears is.
- >
- >So... if I read the description correctly, SBM is a more sophisticated
- >way of tackling the quantization-noise issue than a simple one-half-LSB
- >random dither is, but the two techniques are first cousins.
-
- Is it correct that this is purely a quantization issue? How much of a
- problem is quantization noise in current oversampling A/D converters?
- Is it only audible at very low levels? The Stereopile article that was
- quoted had the Sony folks saying things like "a 100 Hz sine wave at -90
- dB looks more like a sine wave." If that's the main improvement, I find
- it hard to believe that the difference would be apparent to most consumers
- under typical listening conditions.
-
- --
- Larry Spence
- larry@cs.com
- uunet!csccat!larry or sun!texsun!csccat!larry
-