[LAU] 1980's cds: analog to digital conversion

[Folderol]

On Sun, 14 Feb 2010 00:00:23 +0100
fons at kokkinizita.net wrote:

> On Sat, Feb 13, 2010 at 05:37:50PM -0500, Monty Montgomery wrote:
> 
> > The RIAA preemphasis is not a biorthogonal filter.  There will always
> > be at a minimum some phase/group delay as the 'perfect' inverse filter
> > is unstable.  You can only approximate it.  Another example of an
> > analog horror we no longer need to put up with in the digital era :-)
>  
> The RIAA filter applied (normally) in the cutter is
> (in Bode-plot form)
> 
> +6dB/oct up to 50 Hz
> flat     up to 500 Hz
> +6dB/oct up to 2122 Hz
> flat     above that

Does anyone know where they got that figure of 2122Hz from? It's always
puzzled me. Is there some arcane mathematical significance, or was it
the work of an engineer with an hangover?

-- 
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.