[time-nuts] Oh dear

Attila Kinali attila at kinali.ch
Mon May 7 16:19:19 UTC 2012


On Mon, 7 May 2012 10:02:25 -0600
Tom Knox <actast at hotmail.com> wrote:

> 
> Actually the numbers are quite real, play with the math, a small amount
> of jitter in a DAC (X) can have a large difference (Y) when sampling a
> complex wave form especially in the audiophile world where the sound of
> 24bit dac 16,777,216 discrete levels is clearly superior to older
> 16 bit dac 65,536 possible levels in 44.1 KHz to 192 KHz formats.  

Yes, i know that jitter is a pain when it comes to ADCs, but keep
in mind that your audio ADC does have a jitter of a couple
100ps itself. If it's a high end ADC that is. The standard ADCs are usually
in the ns range. For a normal 10MHz XO you measure the jitter in in the lower
10ps at most, a good one at lower than 1ps cycle-to-cycle. Of course, you have
to keep the clock signal clean of any disturbance that might add modulations
to it. But that's a matter of keeping the power supply clean and having the
signal shielded. It's not an inherent property of an Rb to have low jitter.
And as we all know from the recent  hype on the FE-5860As and the
following measurements, not all Rb's are low jitter.

			Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?



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