[LINK] How can analogue be better? [was: all the music in the world]

Stephen Wilson swilson at lockstep.com.au
Tue Jun 2 14:16:11 EST 2009


Jan Whitaker wrote:
> Ivan Trundle wrote:
>> Mock me for being an 'audiophile' if you wish ... 
> I had a professor friend back in the 70s who would only listen to vinyl, never tape. Think cravat, pipe, and a fine port.
Or ... think phase response.  I think the reason digital sounds funny is 
that sampling at 40-odd kilohertz ruins any phase differences between 
the two stereo channels smaller than 25 microseconds.  But the human 
hearing system is sensitive to phase differences of as little as one 
microsecond, when constructing the stereo image.

You can tell just by looking at a vinyl record that it contains signals 
of at least 100kHz (while a CD is limited by anti-aliasing filtering to 
20kHz; MP3 may in effect be lower still).  The coloured rainbow patterns 
seen on an LP's surface are caused by optical interference, indicating 
physical structures in the grooves about the same size as the wavelength 
of visible light - say 500nm (I think these structures are caused by a 
high frequency bias signal applied to the master record cutting 
stylus).  My back of the envelope is that this corresponds to a 
frequency of 100kHz. 

I'm not saying there are 100kHz sound waves in the LP that can get 
through the amplifier and speakers and our ears into the brain.  But 
there can be phase information at the 1 to 10 microsecond range that 
does get through -- but only in an analogue system.

Cheers,

Stephen Wilson.






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