🚀 go-pugleaf

>>Do you have any idea of what >90dB dynamic range really means?
>>
>
>I've once seen a chart explaining the usable dynamic range of a compact disc> in
>professional use (with 16 bit depht). What I remember is :
>
>1)  On the upper end of the theoretical 90dB range they have to cut off 10dB> as
>a clipping reserve, since digital clipping would immediatly destroy a whole
>recording.

Sorry to disagree but to illustrate: I asked a  Polygram  engineer  during  a 
live recording session how it was possible to record to apparently <1dB of 
clip. He shrugged and just replied "It's ok if they play in tune" 8-)

That was a few years ago when the recording was onto 1610. Since then 
recordings at > 16 bit are possible if not common, but your point is valid 
for unpredictable sound sources.

A long time ago we designed a limiter for use before A/D -- it has never sold 
for the purpose.

>2)  You cannot really use the lower 30-40dB of the 90dB range, since> distorsion
>becomes too high (up to 40% in the first 10db range, as far as I remember).> The
>reason for this is the decreasing resolution of the sampling device at lower
>input levels.

Sorry.  Fade a signal down to -80dB and listen. Just some added hiss and _no_ 
noticable  distortion.  This  is  what dither is all about.  I have a digital 
fader (re-dithered) which sounds ok when the music sound is at the same level 
as the noise.  Switch the dither off and there is your  distortion  (or  more 
precisely  quantisation noise which sounds a bit like crossover distortion to 
me).

Even if there is distortion, it would have to be very bad to exceed the noise 
floor.
All this does of course assume that the CD DAC is good, but that is not the 
subject of this thread.

>
>Thus the reamining usable dynamic range of a compact disc doesn't exceed
>40-50dB, that is still a lot but can be outperformed by analog recordings.
>
Perhaps I should pass you the fader handheld when it's faded also to zero but 
the monitor gain is right up. 
What is 80dBs above 1 watt per channel?

  TC. 
    E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk