Re: arsclist Tubes will not die

[Jerome Hartke <jhartke@xxxxxxxxxxxx>]

James Perrett wrote:
> 
> Mike Richter wrote:
> >
> > At 04:50 PM 11/13/2002 -0600, Premise Checker wrote:
> > > >From the Transhuman news list:
> > >Date: 13 Nov 2002 08:56:29 -0800
> > >From: James Rogers <jamesr@xxxxxxxx>
> > >To: fork@xxxxxxxx
> > >Subject: Re: Tubes will not die
> > >
> > >On Tue, 2002-11-12 at 20:07, Jon O. wrote:
> > > >
> > > > James, this is a JOKE! Perfect CD reproduction?
> > > >
> > > > How can you say this -- one is bits and one is vibration. They both have
> > > > their limitations, but a CD sampling rate is similar to a Mega Pixel
> > > > rating on a digital camera. It isn't the thing, but a representation
> > > > of the thing. So is a CD. I suppose you can tell me that a 20 mega pixel
> > > > digital camera is just like "seeing" photo and 512 bit sample of music on a
> > > > CD is equivalent to the live production.
> > >
> > >
> > >The best analog recording formats (which are actually digital when you
> > >get down to it) have less signal fidelity than an ordinary Red Book CD.
> > >You can record Red Book audio that maintains perfect fidelity WELL below
> > >the noise floor and beyond the frequency range of vinyl, so a perfect
> > >reproduction of any signal there is trivial.  I would humbly suggest
> > >that you study up on sampling theory, signal processing, and other bits
> > >of relevant trivia.  You are seem to be demonstrating a classic
> > >misunderstanding of how sampling actually works.
> >
> > Bah, humbug!
> >
> > There is a good deal of truth in the preceding paragraph, but in all it is
> > not consistent with the tests I ran many years ago. I will address here
> > only the frequency argument.
> >
> > It is certainly true in linear analysis - the sort we engineers find
> > comfortable - that frequency response on CD-DA is superior to that on
> > vinyl. However, we do not hear pure tones and linear analysis does not tell
> > us all that we need to know for sound reproduction.
> >
> > The issue here is not frequency response per se but response to waveform
> > and, with that, to phase error. I have repeatedly run the following simple
> > demonstration. Assume that the individual asserts that he can hear nothing
> > above 15 KHz.
> >
> > 1. Set up two signal generators, both at 8 KHz, one for sine waves, the
> > other for square waves
> >
> > 2. Using wide-band amplifiers and headphones, challenge the subject to
> > adjust one of them - amplitude and frequency - to match the other.
> >
> Mike - and any others interested in this subject in depth. There is a
> similar but possibly better informed discussion happening on the
> pro-audio list at the moment. If you take a look at the recent archives
> you'll see how valid this particular test is considered. For more
> information on the ProAud list, please send an e-mail containing the
> single word "info" (without the quotes) to pro-audio-request@xxxxxxxx
> 
> Cheers.
> 
> James.

The sine-square wave test is a bit questionable, since the sinusoidal
fundamental component of a square wave has a higher amplitude than the
peak of the square wave itself. Although the test assumes absolute
hearing cutoff above 15 kHz, that is usually impractical. In addition,
higher order harmonics of the square wave will interact via
intermodulation distortion in a wide bandwidth receiving system and thus
affect what is heard by the listener.

This thread seems to be an apples vs. oranges/bananas/grapefruit/pears
argument. Technical analysis deals with accurate reproduction of
frequency and phase response, or time domain equivalents, without
introduction of harmonic or intermodulation distortion and noise. Such
results should be repeatable by others with different equipments.

Personal preferences are very subjective, are usually not as repeatable,
and may reflect an expected outcome of the listener. A recent
communication reported a "fantastic" improvement in CD sound when green
paint was applied to the rim in order to prevent the laser light from
"leaking out" the edge.

Jerry
Media Sciences, Inc.


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