mswlogo;543997 Wrote: 
> One smash of a symbol will start full scale and decay in amplitude. As
> it decays the performance of those lower bits get more important.
Yes, absolutely. As the cymbal crash dies away, the lower level detail
is no longer masked by the loud crash. Therefore you need accurate
reproduction of the lower bits to hear the subtle aspects. So we are in
agreement? Er, no...

Let's say you're listening to a piece of music and there's a cymbal
crash peaking at 100dB SPL, then it decays. Let's be extreme about this
and say there are decay details at 4dB SPL you need to be able to hear.
(We'll ignore for the moment that your lisening room can't possibly be
quiet enough). In order to hear those details, you need a system
capable of a 96dB dynamic range (ie. a full 16 bits). The voltage of
the signal at 4dB is 1/65536th of the voltage at 100dB. If the voltage
that delivers 100dB is 10V, the voltage that gives you 4dB is 0.152mV.

So far so good. Now turn the volume down, so the cymbal crash is at
94dB. The voltage to generate that level is half that required for
100dB: 5V. And so the subtle detail in the decay will now be playing at
0.076mV, which will give an output level 6dB lower than it was before,
ie. at -2dB SPL. But hang on - you can't hear anything beneath 0dB SPL.
Those subtle details that were audible in the decay when the peak level
was 100dB are not audible when the peak level is 94dB.

Once again: as you turn the volume down, the required dynamic range
reduces. I'm not talking about the changing levels within a track, I'm
talking about adjusting the playback level with a volume control. If 16
bits of resolution is enough when you're listening at 100% on the volume
control, then 15 bits will be enough when it's at 50% (assuming a linear
scale for simplicity). On the other hand, if your system/ear is
wonderful enough that you need 20bits at 100%, then you'll need 19 bits
at 50%. But the principle remains the same: to retain the same amount of
audibility of fine detail, as you reduce the playback level you can
afford to lose dynamic range.


-- 
cliveb

Transporter -> ATC SCM100A
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