Jitter Immunity with UltraLock™
Part Two of Two
Just how good is UltraLock™ technology in
eliminating jitter? Well, at the risk of sounding like an
overstatement, there is nothing else on the market that can even come
close! Here are the facts.
Figure 1. Typical DAC Performance WITHOUT UltraLock™
Red = Distortion (Left Scale)
Blue = Jitter Input (Right Scale)
Green = Jitter at the AES Receiver Output (Right Scale)
The graph above is a look at a typical D-to-A converter which
receives its clock signals directly from an AES receiver. The blue
curve is the jitter output generated by the test generator. The
red curve is a plot of Distortion versus jitter frequency, and the green
shows that jitter level coming from the AES receiver. The DAC does not
have a second stage PLL and obviously does not have
UltraLock™. Also the Blue curve is only one half the AES
recommended jitter tolerance for an AES receiver. The Red curve
shows the variation in distortion versus the jitter input. At one
point, as shown by the red curve, distortion actually reaches -55 dBFS
(0.1778%), not exactly Hi-Fi! Yet many manufacturers are promoting
this design type as "Professional". The green curve also shows
that at some frequencies (1.5 kHz to 9.5 kHz) the interface jitter
output from the AES receiver is actually greater than the
output of the Audio Precision test set, indicating an amplification of
the incoming jitter signal, another reason to totally avoid this type of
design.
The sonic effects of such a circuit design are very audible. A
side-by-side listening comparison between this common design and the
output from a DAC-104 is quite surprising for most listeners. The
most common observation is "muddiness", a significant amount
of additional low and mid frequencies that are clearly heard in the poor
design. New, unexpected, and unwanted audio. There is also a
very significant loss of stereo imaging.
Figure 2. DAC-104 Performance WITH UltraLock™
Plots: Blue = Jitter Input (Right Scale)
Green = DAC-104 Distortion (Left Scale)
With the DAC-104 by contrast, the effects of jitter are un-measurable
and the absence of jitter is clearly audible. The above
curves are using the same amount of jitter input. However, the
input level can be raised to the limit of the AP System 2, 1000' of feet
of cable can be added and the performance will not change! If the
AES receiver can decode the waveform, and we are using a receiver that
has an exceptionally wide signal tolerance, then the output from the
converter will be totally free from jitter artifacts. The
distortion from the DAC-104 for instance, is 0.00079% with any signal
input, at any sample rate, with ANY amount of jitter.
The same performance improvement is built right into the ADC-104,
where it is even more important! Distortion that is created during
the encode process is permanent, and can never be removed.
The tracks you record with inferior designs are always going to have the
type of distortion shown in the first example above. A total waste
of time and money? You decide.
Why put up with yesterday's designs, when for the same investment,
or less, you can have performance that is truly at the cutting edge
using the Benchmark UltraLock™ Technology.
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