Re:Re: Looperlative LP1 - sample rate

[a k butler <akbutler@tiscali.co.uk>]

>  No sampler can "guess" a sine wave from a square.
>How would it know that you wanted a sine wave? Think of sines and 
>squares as just different shapes.
>
>Gareth

hi Gareth,
well believe it or not that's exactly what a good D/A converter does,
(and what a bad one tries to do)
The converter assumes that the signal it is trying to re-create is
band limited, i.e. that it is describable as a mixture of sin waves all of
which are below the Nyquist frequency.
In essence, the digital output is passed through a lo-pass filter with
a cut-off at around 20kHz.
As you're no doubt aware, all filters "ring" somewhat, they have
something of a tendency to oscillate at their resonant frequency.
The converter can then guess at the waveform at high frequencies,
even though it's only represented by a few samples.
By varying the Q of the filter, the amount of "ring" is controllable,
which is why some converters sound dull, and some sound
bright but unnatural.

hope all is well in Wales

andy butler