[BC] dueling algorithms and audio quality

[Robert Orban]

At 07:07 PM 10/2/2009, Broadcast List USER wrote:
>Well, yes, and no.
>
>There are some pretty good D to A converters.  Between oversampling,
>dither, digital reconstruction filters, they can be pretty good.
>
>Yep, I am one of the many who don't like what CDs did to music.  No
>one had the vision to use high sample rate Delta Modulation.  Still,
>some of the Telarc and other recordings sampled at 180 kHz and above
>were stunning.  For the most part, you cannot get them now, but there
>are some very high quality digital recordings on the oddball web
>sites.  One of the not so good thins is that while the recordings are
>pretty darned good, the performances are not so stellar.
>
>On the other hand, I agree with you.  For example, if you use a
>computer to compose a CD with a 20 kHz square wave on an audio CD,
>what do you get when you play it back through a CD player?  Well, it
>is a somewhat distorted (because of problems with the reconstruction
>filters) 20 kHz SINE wave.  The filter will rub off all the corners by
>removing the harmonics, though not perfectly.
>
>High slew rate signals are screwed up by the anti-aliasing filters on
>the recording side too.
>
>Then again, tape saturation, the non-linear problems with tape
>recording, and the NOISE, are not issues at all.
>
>If we had a MUCH higher sample rate, things would have been just
>fine.  If we had that, the D to A would not be an issue, and the
>reconstruction filter would be trivial.
>
>Then enemy of good enough is perfect.  In my opinion, 44.1 kHz 16 bit
>linear is just good enough for broadcast.  It isn't perfect, but for
>car listening it is more than enough.  For critical listening at home,
>maybe not, but we have the restrictions of the mediums (AM & FM).

You might want to read the following AES Journal engineering report:

Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution 
Audio Playback [Engineering Report]

Claims both published and anecdotal are regularly made for audibly 
superior sound quality for two-channel audio encoded with longer word 
lengths and/or at higher sampling rates than the 16-bit/44.1-kHz CD 
standard. The authors report on a series of double-blind tests 
comparing the analog output of high-resolution players playing 
high-resolution recordings with the same signal passed through a 
16-bit/44.1-kHz "bottleneck." The tests were conducted for over a 
year using different systems and a variety of subjects. The systems 
included expensive professional monitors and one high-end system with 
electrostatic loudspeakers and expensive components and cables. The 
subjects included professional recording engineers, students in a 
university recording program, and dedicated audiophiles. The test 
results show that the CD-quality A/D/A loop was undetectable at 
normal-to-loud listening levels, by any of the subjects, on any of 
the playback systems. The noise of the CD-quality loop was audible 
only at very elevated levels.

Authors: Meyer, E. Brad; Moran, David R.
Affiliation: Boston Audio Society, Lincoln, MA, USA
JAES Volume 55 Issue 9 pp. 775-779; September 2007