DeepColor - Ultra Low Jitter Clock for 24 Bit Audio
Including a brief Introduction to Design Guidelines for High Resolution
Audio Clock Applications
by Ing. Michael Gerstgrasser
on a beautiful day at certain seasons we get touched by the
purity and depth of the colors of the landscape we live in, suddenly
experiencing what we have known all our lives as something
exceptionally new and outstanding.
Sometimes we enjoy the same emotional excitement with fine audio gear,
letting us dive into the flow of music we love and feel deeply the
suspense and relaxation of harmony and rhythm, establishing a sort of
intimate communication with the performing musicians overlaid by the
ideas of composers and recording engineers.
As often with audio devices, there is a strong desire to find out the
ingredients and technical specs that are relevant for what excites and
touches us most in reproducing music like "LIVE".
Many electronic design aspects have been said to be the "really
important" ones in the past, but not one has been proven to be "the
one" to rely on only until now. Not even the most extended set of
measurable specs seems to be able to define what someone judges to be
All thats left for approaching any aspect related to the improvement of
audio gear is to search for an electronic design optimum and have a
look at what may have been overlooked or at least not been realised to
be sonic relevant.
When the 16 Bit / 44.1 kHz standard for CDs, as the very first widely
spread digital audio format for common use, was specified in the early
80ies of the last millennium, an expected 20Hz to 20kHz human hearing
ability together with the sampling theorem stated by Harry Nyquist,
Claude Elwood Shannon, Vladimir Kotelnikov and John Macnaughten
Whittaker roughly eight decades ago, were taken as the basis to
calculate the theoretical requirements.
Whereas the resolution in terms of quantisation always has been in the
focus of general discussions reflected by several different approaches
in AD/DA conversion the more subtle issues of resolution in the time
domain were discussed much less.
Within the given limitations of the 16 Bit / 44.1 kHz CD format, some
considerable improvements developed over time. I recall my listening
experience of my brothers very first and brute sounding Philips
CD-player against the sweetness and accuracy of his Sondek turntable at
that time. The standard quality we get now in digital consumer audio
both equipment-wise and due to refined mastering has largely improved
Though, surprisingly much room for audible improvement still can be
found, when concentrating on the behaviour of the crystal oscillators
implemented in any kind of digital audio device.
Among several configurations the oscillator arrangement found by Edwin
H. Colpitts in the early 1900's has been proven to perform very well in
Several variants of the Colpitts circuit exist, using tubes, BJTs, CMOS
or FETs and others as an active device. Despite choosing any kind of
favourite circuit, many considerations have to be taken into account
and balanced out carefully to operate a chosen arrangement at its
sweetest spot and to obtain the very best overall performance at the
end of pipe.
Extended measuring effort, theoretical investigation and circuit
simulation was done during development of the "DeepColor" clock design.
Though I find SPICE simulation here much more meaningful than with
analogue audio circuits and optimising sound performance develops
rather straight forward aided by this great tool for electronic circuit
analysis, a lot of prototype listening sessions within an appropriate
sensitive 24 Bit audio chain were necessary in order not to get trapped
or mislead by excellent figures only.
How does it Sound ?
you should not expect any changes in tonality as frequency
response is not affected, simply
everything will sound different, from a tender swinging triangle down
to the mightiness of the deepest notes your chain is capable of.
You will regain any transient resolution lost, all character and color
provided by your records. Any uncertainties are wiped away, a stable
and reliable image is gained that makes it easier to follow any detail
while keeping track to the whole, regardless of how complex or
minimalistic the music you play is.
In the higher region a certain kind of sharpness and harshness
re-integrates into sound as very fast transients, enhancing "3D"
focusing. There is sweetness from cymbals, astonishing attack with
percussion and intimate clarity from voices. In the low region you
regain the highest definition possible and a kind of transparency, you
would not have expected there, transcending into a virtually unlimited
sense of room perception. Improvement of "3D" perception is
more pronounced at out of centre listening positions.
Any sound and acoustical event is highly distinguishable by its purer
and richer colors and a timing of the tune that does not lay back nor
get into any hurry providing a strong feeling to stay "just in time",
whatever rhythm or mood your music follows.
The above attributes are usually expected in describing speaker
behaviour and are most likely associated with quite some investment.
Regardless of how perfect or sweet speakers may sound, it's normally
quite a challenge to balance analytical and emotional aspects there,
whereas this is in no way conflictive for jitter improvement. Treating
jitter behaviour at the front end of a chain, you always gain - or lose
- in detail as well as overall. A very well designed clock lets you
your records even more authentic, precise and with all the beauty music
can bring to us.
Its pretty much the same effect when using a really nice lens instead
of a blurry one when taking pictures.
Basically absolute EVERYTHING in music and sound is related to time.
What was of no concern with analogue audio besides wow and flutter of
turntables and band machines, becomes a completely new significance in
digital audio in terms of sound performance all the way from close to
DC over the audio band up to RF frequencies.
To pioneer the challenge of full 24 bit audio clock resolution, the
DeepColor clock was designed for and - believe me or not - it was as
much joy for me to learn that much about unexpected sonic impacts of
electrical and physical phenomena at this specific application as it is
for me to enjoy the result now.
At the very end it simply is plain fun and joy to listen to whatever
you like, turning on your heat or let you slip into magic meditation.
AIM, TECHNICAL DESCRIPTION, CIRCUIT DISCUSSION and DESIGN GUIDE LINES
Low audio band and sub audio band jitter are not recognised to be of
special sonic relevance yet. My findings are different from mainstream
opinion here and with the DeepColor clock you will be able to prove
Two examples to illustrate jitter that can be found on
| Fig. 1 Random low frequency noise on
sound card with internal clock used.
| Fig. 2 Jitter of PHILIPS CDR 795 PLAYER in
with 32k and 256k FFT points (0,2 Hz resolution,
What can be seen here is that considerable amounts of audible jitter
can be found in consumer and pro-audio gear.
put the superior performance of the "DeepColor" clock design into
perspective, comparison with two other after market super clock designs
acknowledged to work fine, is provided as far as useful. This
schematics are free for non commercial use and can be found to download
LC Audio XO3
Kwak clock ver7 schematic
Rather than only claiming superiority - as seen from most other clock
manufacturers - this compilation focuses on basic technical relations
for a better overall understanding on the very interesting topic of
jitter in audio applications. Though there are many figures presented
below, it's suggested, to bear in mind the overall picture as specific
figures may vary from sample to sample and SPICE modeling also never is
Two major statements always have to be kept in mind when dealing with
jitter in audio audio applications.
First of all, a very good clock signal especially tailored for the AD /
DA converter is always preferable to an external clock, avoiding the
additional sources of PLL jitter, cable jitter and others.
Secondly, jitter does not affect sound performance during digital
processing. Jitter only comes into play when converting signals from
the analog to the digital domain and vice versa. The only exception
here are sample rate converters that mimic this task back and forth
with the help of digital algorithms. For SRCs the input clock jitter
AND the output clock jitter contribute to the overall degrading of the
digitally coded audio signal leaving the SRC.
Having said this, its easy to understand that following applications
benefit most from an ultra low jitter module like the DeepColor clock :
- AD converters in any kind of device
- DA converters in any kind of device
- SRCs in any kind of device
- Clock distribution systems (in order to sync a whole digital chain
with the device of choice rather then just outputting a so called
CRYSTAL SIGNAL PURITY and OSCILLATOR SUPPLY CURRENT
first thing important to consider of a quartz oscillator circuit
may be the sinus signal purity of the crystal in the oscillator itself.
Due to finite impedance and certain hardly predictable behaviour of
power supply circuits at higher frequencies, the current drawn by the
active device also has unexpected audible relevant impact.
It modulates the effective supply voltage at side band frequencies
above the centre frequency and sometimes even down all the audio band.
Because the correlation with the centre frequency never is 100%, this
AC voltage drop may rather be seen as a kind of inducted supply noise.
Depending on circuit layout, AC magnitude and frequency spectrum
involved, the current drawn by the active device may therefore easily
overlay and effectively degrade noise performance of the supply by
several orders of magnitude.
| Fig. 3 DeepColor Clock Signal Purity and AC Power
|| Fig. 4 BJT Clock Clock Signal Purity and AC Power
|| Fig. 5 FET Clock Clock Signal Purity and AC Power
What can be seen here is that the DeepColor clock operates the crystal
at a very clean sine wave oscillation and that the power supply
interaction is greatly reduced by a factor of more than ten remaining a
smooth signal here as well.
OSCILLATOR POWER SUPPLY REJECTION
the output amplitude of the oscillator as a reference, it is
useful to calculate the effect of variations in supply voltage with
respect to the output signal.
What in data sheets commonly is referred to as the PSRR figure, is
normalised to the sine wave output of the oscillator here and reflects
directly how much the sine wave output signal of a certain oscillator
circuit is degraded by any kind of noise or line and load regulation of
its supply voltage. Any remaining distortion signal at this point
translates directly to clock jitter via some complicated maths.
Though providing ultra low jitter figures got common use for
advertisement reasons, it must be stressed that clock jitter figures
are absolutely useless if not specified for a certain frequency or
In case of sine wave distortion signals below the Nyquist frequency,
one will get side band lobes at a distance related to the frequency of
the distortion signal and depending on the level. With random noise as
distortion one will get a raise in noise level depending on band width
Advanced high order filtering of the oscillator sine wave output signal
of the DeepColor clock provides exceptional noise distortion rejection
at the most critical point of the clock circuit. One has to keep in
mind that phase jitter will occur with all signals that overlay the
oscillator sinus and will translate audible relevant even down to the
| Fig. 6 DeepColor Clock Oscillator PSRR
|| Fig. 7 BJT Clock Oscillator PSRR
|| Fig. 8 FET Clock Oscillator PSRR
What can be seen here is that the DeepColor clock provides superb audio
band and sub audio band power supply rejection, reducing any jitter
prone signal distortion by oscillator supply imperfections at the point
of the comparator threshold to negligible amounts. All supply signals
are phase locked to show a worst case scenario.
SIGNAL and NOISE SHAPING
the sine wave from the oscillator to a square wave clock
signal can easily be done by a high speed comparator. There are brick
wall limitations to jitter performance though at this point that can
not be overcome by any design tricks. Few but very basic laws determine
random jitter performance, which lead naturally to general design
Assuming the rest of the circuit to be ideal, the minimal random phase
jitter achievable depends on the peak to peak noise of the signal and
the comparators input voltage noise in relation to the signal's slew
rate at the point of threshold. This jitter is basically wide band and
sometimes referred to as random jitter RJ in ultra high speed
comparator data sheets. RJ figures have to be interpreted correctly, as
they depend upon the slew rate of the signal. Very low RJ figures
achievable with GHz signals are of no meaning in an audio clock
application with limitations to some tenth MHz.
The mechanism of random phase jitter, actually representing the
uncertainties about the exact time for toggling from low to high and
back again, best can be understood by a signal traveling a peak to peak
noise floor at a given speed. Simplyfied random jitter can be seen as
the equivalent to noise in the analog domain. One difference between
random jitter and analog noise is that uncorrelated noise at the point
of threshold does sum up as jitter rather linear than in quadratic
terms as it would be with analog noise.
| Fig. 9 noisy signal passing a noisy threshold
|| Fig. 10 ideal signal passing a noisy threshold
|| Fig. 11 noisy signal passing an ideal threshold
What can be seen here is that random phase jitter is added by the noise
floor of the oscillator signal and by the noise floor of the comparator
input in relation to the speed of passing through these noise floors
hysteresis to the comparator may help in preventing ultra high
frequency oscillation under certain conditions, but can not further
improve jitter performance. What can be done to optimise audible
performance is, to exclude jitter frequencies in the audio band and sub
audio band as far as possible. This is accomplished for the DeepColor
clock by inserting a high order filter between oscillator and
comparator. A low impedance, low noise, high PSRR output stage is
implemented in the DeepColor clock's gain block to drive this filter at
an unusual high signal level.
By the way, Fig 11 allows an intuitive understanding of phase noise
figures. At the point of threshold noise in the y - axis has basically
the same effect and cannot be distinguished from noise in the x - axis.
What was considered as noise in the y -axis until now can therefor be
seen and expressed also as noise in the x- axis which means variations
in frequency. Normalised as a fraction of the oscillator frequency
phase noise figures are convenient when comparing the effects of
circuit design at different oscillator frequencies
| Fig. 12 DeepColor oscillator output noise
|| Fig. 13 BJT Clock oscillator output noise
|| Fig. 14 FET Clock oscillator output noise
Y-Axis scale is V/Hz½.
What can be seen here is that the DeepColor clock oscillator has
negligible low output noise up to 1 MHz.
| Fig. 15 DeepColor oscillator RJp-p
|| Fig. 16 BJT Clock oscillator RJp-p
|| Fig. 17 FET Clock oscillator RJp-p
What can be seen here is:
Calculating a 10 Vpp signal with an oscillator output noise around 500
nV/Hz½ from the DeepColor clock will translate to a
theoretically minimal achievable random jitter of around 10 ps at 22
MHz. This amount of random jitter is limited to the upper MHz region
falling rapidly to ultra low values for any frequencies below 2 MHz.
Targeting a tough 500 fs, the DeepColor clock gives a considerable
jitter improvement over existing designs by a factor of roughly 20 to
200 throughout the audio and sub audio band!
The DeepColor clock design would benefit from a noiseless (!)
comparator dropping RJp-p below 1 MHz wide band into cellar.
Calculating a 80 mVpp signal with an oscillator output noise around 2,2
nV/Hz½ from the BJT clock example above will translate to a
theoretically minimal achievable random jitter of about 90 ps. RJ is
distributed equally over frequency. This design would benefit from a
noiseless (!) comparator dropping RJp-p to around 25 ps wide band.
Calculating a 700 mVpp signal with an oscillator output noise around 1
nV/Hz½ from the FET clock example above will translate to a
theoretically minimal achievable random jitter of about 10 ps at 22
MHz. At around 500 Hz the output noise of the oscillator is peaking to
about 300 nV/Hz½ which translates to jitter around this
frequency of about 380 ps falling to around 15 ps at 100 kHz. This
design would benefit from a noiseless (!) comparator dropping RJp-p to
around 2 ps at 22 MHz / 370 ps falling to 7 ps from 500 Hz to 100 kHz.
calculations assume a low comparator input voltage noise of 6
nV/Hz½, held constant here to ease maths. Measurements show
this is a fair value for some widely available real world high speed
Obviously only intelligent use of standard filter techniques for the
oscillator signal - like practiced in the DeepColor clock design -
allow to benefit substantially from ultra low noise comparators having
even lower input voltage noise.
It has to be kept in mind that all RJ figures calculated here represent
absolute design limits only, one may or may not come close to,
depending on a clever balance of ALL requirements necessary to reach
Though the DeepColor clock is designed to perform in an outstanding way
also in this aspect, the audible irrelevance of a one number
specification was clearly outlined above which can not be stressed
enough. The RJp-p figures are based on a roughly 22 MHz sine wave
signal and 100 MHz band width, crest factor is assumed to be 6 for
simplicity. Please note that as an optimistically assumption the noise
floor of the threshold is considered to be constant over frequency
throughout all calculations.
There is an other aspect worth to be look at, concerning the
arrangement of filter components for achieving best results. A
comparator input voltage noise is specified with the input shorted,
requiring to keep
the source impedance as low as possible - if above RJ figures should
| Fig. 18 DeepColor Clock Output Impedance
|| Fig. 19 BJT Clock Output Impedance
|| Fig. 20 FET Clock Output Impedance
What can be seen here is that only the DeepColor clock provides
sufficient low output impedance in the audio band and sub audio band,
shunting the input impedance of the comparator very efficiently by a
optimised filter topology. Therefore no further degrading of the
comparator's input voltage noise in this frequency spectrum occurs. In
other words, the DeepColor clock oscillator design is not compromising
the noise performance of the comparator at all.
of how low the input voltage noise comparators may become
available in future, the DeepClock's superior design concept proves to
be outstanding also in this aspect.
There are other jitter components determined by variations in power
supply, signal purity, interfacing and others that may add to the total
amount of phase jitter in a clock and these ones also have to be kept
under tight control by circuit design, layout and proper interfacing.
Top Notch / Active Interfacing / Time Reference
low impedance, high voltage output of the DeepColor clock's
oscillator circuit allows for driving the load directly or via cable.
This is a big advantage as only a single frequency sine wave has to be
transmitted which saves a lot of cable, EMI and termination troubles.
The very small receiver unit can be mounted on top of the AD / DA
converter and the DeepColor clock itself can be housed elsewhere. Two
choices can be made here. Either a receiver unit that makes use of a
high speed comparator with a high order filter in front of it or a
receiver unit containing only the the high order filter and a sine wave
The receiver module with the sine wave clipping circuit has the
advantage of feeding the AD / DA converter threshold directly and
without any additional noise source in between. The receiver module
with the comparator circuit has the advantage of a slightly higher slew
What will result in lower jitter therefor depends on the noise level of
the clock input of the AD / DA converter. The trade offs between speed
and noise are outlined above in detail, though chip manufacturers
normally don't specify the performance at the clock input of their AD /
| Fig. 21 DeepColor Clock top notch RJp-p
What can be seen here is that the DeepColor clock design allows for
virtually loss free interfacing.
Calculating 1 nV/Hz1/2 for the threshold of the AD / DA converter and
using the clipped sine wave circuit receiver unit will give a RJp-p
directly at the clock input of the AD / DA converter of slightly below
90 fs within the audio and sub audio band. Not that bad indeed!
also can be learned here is that no matter if you use as a time
reference a standard quartz crystal or atomic clocks - which in fact
are capable to provide several orders of magnitude better long time
stability << 1 Hz - the random jitter within the audio
sub audio band is heavily degraded even by the very simple task of
transforming a sine wave into a square wave done by any pretty good
comparator. Every complex signal processing - like PLLs for frequency
shifting for example - will degrade random jitter figures even more.
This puts an interesting light on the fact that we seldom see RJ versus
frequency plots, even for Euro 10 000.- rubidium audio clocks.
It also makes clear that only a widely unprocessed clock signal that is
fed directly and with the appropriate frequency to the AD / DA / SRC
device ensures best performance.
Furthermore it makes clear that when RJ considerations at the side of
the clock unit are consequently pushed to the limit, its up to the AD /
DA manufacturers to specify their units in more detail as they are
becoming the dominant part with respect to RJ figures.
Room for a first step overall improvement is defined easily:
1.) push down the noise figure of the threshold
2.) push up the clock frequency
3.) push up the amplitude of the clock output
4.) filter out unwanted noise if the clock signal
What makes the DeepColor clock design such nice is that it will not
limit further improvements there.
DeepColor CLOCK MODULE SUPPLY and BRAKE-IN TIME
to nested on board supply voltage stabilisation circuits not
covered in detail here and the low power consumption of the DeepColor
clock, almost any internal supply of the device to upgrade can be used.
The module accepts voltages in the range of plus / minus 12V - 35V and
draws a current of roughly 50 mA. If unregulated supply is used, ripple
should not exceed about 50 mVrms as a rule of thumb.
A quiet external supply in general allows for better results in terms
of timing, flow and room perception as described above.
The DeepColor clock does not make use of any exotic parts but rather
relies on solid construction. But as with any sound device, you may
allow some time to settle before judging.
Half a week of continuous operation will be fair, any further changes
will be very sublime and it's more likely that it will take several
weeks to realise the full potential of the DeepColor clock rather than
the clock's performance will change substantially.
Clock System Requirements for Digital Audio Chains
obvious that a word clock system is the only way for complex
digital audio chains to maintain synchronous operation of several
digital audio devices without accumulating clock jitter. Every device
of a digital chain must therefor be driven from a single word clock
frequency or from a clock frequency that is phase locked onto it.
Otherwise samples will get lost and the audio signal will be corrupted.
For convenience word clock frequencies are normally distributed as the
standard sample rate frequency or multiples from that.
This implies that such word clock frequencies normally must be shifted
by a frequency multiplier or divider prior to feeding the AD / DA chip.
Complex clock signal processing will have heavily adverse effects on
jitter performance as clearly outlined above.
Simply the only ( ! ) way out of this dilemma is to do it just the
other way around. Use an ultra low jitter clock that generates exactly
the right frequency
for your device of interest and lock the word clock and the rest of the
digital chain onto that. Remember that clock jitter has its importance
during AD / DA conversion. As long
as you stay in the digital domain, clock jitter does not affect sound
The DeepColor clock provides a second output to allow for external
phase locked frequency conversion to a 10 MHz reference or standard
audio clock distributing frequencies.
Almost any professional clock distributing device allows to lock onto
an external 10 MHz reference.
Depending on whatever recording or playback is the critical task in
your application, more intelligent designed word clock distributing
devices provide even more flexible switching options to phase lock onto
severals frequency reference inputs.
Things are simple as long as the border between analog and digital
domain is crossed only once. An external DAC driven from a transport or
from a DAW during playback or an external
ADC driving a DAW during recording would be examples for that. In
digital chains like that, there is no quality degrading limit for
adding digital devices in between, as long as they all work at the same
sample rate derived from one word clock.
In case of playback the word clock has to be locked onto the DA clock -
in case of recording the word clock has to be locked onto the AD clock.
As a footnote it has to be said that for digital recording chains
jitter accumulation isn't really a problem and word clock is of no
benefit as long as there are no multiple branches for effect devices
Things get more complicated with digital audio gear that make use of
sample rate conversion.
In that context SRC devices are best understood and treated similar to
any devices that perform a digital to analog plus an analog to digital
conversion within the same shell. SRC's basically always have two clock
inputs: one for the incoming signal - as if it were a DA converter -
and an other one for the outgoing signal - as if it were an AD
You are happy if the SRC is inside the device at either end of your
digital chain. An external DAC accepting sources with a wide variety of
sample rates or just from a specific transport with a different sample
rate would be an example for that. Such designs are sometimes named as
Though inside the same shell with such upsampling DACs the jitter
behaviour of the SRC and that of the DAC should be considered
separately. The outgoing SRC clock and the DAC must be driven from the
same ultra low jitter clock. This clock frequency is important only for
that device and hence isn't the one the other devices in the digital
audio chain must be locked onto.
A SRC is jitter sensitive to its incoming clock frequency as well as to
its outgoing clock frequency by measuring the difference of those
frequencies permanently . The incoming clock frequency of a SRC is
commonly extracted from the incoming digital audio signal data stream.
This means that the source device for the SRC has to be clocked with an
ultra low jitter clock as well.
In this case the SRC's sourcing device clock frequency is the one the
word clock has to be locked onto and that word clock must be
distributed to any device that may be ahead in the digital chain.
In rare cases where jitter impacts are considered throughout a complete
chain, the SRC may be fed with a data stream and a separate data clock.
In this case the SRC device has to be operated with an additional ultra
low jitter clock at its data clock input. This clock frequency has to
be fed to the sourcing device and is also the one the word clock has to
be locked onto and that word clock must be distributed to any device
that may be ahead in the digital chain.
For SRC devices in the middle of a digital chain multiple word clock
frequencies have to be distributed accordingly to the above - even if
they are basically of the same value.
One conclusion of the above is that SRC's aren't that well suited for
jitter rejection - and there are other reasons for this as well.
Preserving Signal Integrity at 16 Bit and at 24 Bit
is audible or not always has been and will be under question. But
what can be calculated is the amount of jitter that does not corrupt AD
/ DA conversion. To put things into perspective,
lets have a look on the time step accuracy needed, if we sample with
full 16 Bit or 24 Bit resolution within the audio band. Lets generously
assume the audio band to be 10 Hz to 100 kHz.
Imagine for a moment that we wouldn't sample at fixed time slices but
every time the analoge audio signal moves one bit in amplitude. Let's
further assume that the full scale input range of our imaginary AD
converter is 2.5 Vpp. Now let's calculate for only one half bit in
order to preserve signal integrity at various analog signal frequencies
at the point of their maximum slew rate.
|Analog Signal Frequency
||24 Bit Time step (1/2 LSB at 2.5 Vpp FS)
|| 16 Bit Time step (1/2 LSB at 2.5 Vpp FS)
Fig. 22 Signal Integrity Demands at 16 Bit and at 24 Bit
What can be seen here is that 24 Bit audio is highly demanding with
respect to the correct timing of the samples. Didn't these ingenious
fellows tell us that a hundred years ago?
seems to be well within reach for the DeepColor clock even for 24
100 kHz when operating with an excellent AD / DA
converter, lies for about two orders of magnitude without reach of
Of course there is no such sample rate like 1 / 100 fs equivalent to
10.000.000.000.000 Hz - in real world it rather will be 196 kHz - but
looking at the scenery from that side gives a good and more intuitive
understandable picture of the accuracy involved.
When real world digital audio signals are converted back to analog,
exactly above time step accuracy is translated back into the analog
signal with the help of the low pass reconstruction filter.
What I want to highlight here is that full 24 Bit audio signal
processing is really challenging and to put it simple, you won't get
full 24 Bit resolution with less than perfect clocks. Any time you are
in doubt about the precision needed for the exact sampling time,
remember that for frequencies close to the Nyquist frequency there are
only slightly more than two samples for any period
from which the original sine wave in exact frequency AND exact
amplitude has to be restored.
For those with a philosophic attitude that may ask themselves: "do we
hear such small variations in time span like 100 fs ?" - the best
answer I found for myself was: "Do we prefer 24 Bit over 16 Bit ?"
DeepColor clock proves to be a unique yet beautiful design approach
to support digital audio up to the highest resolution.
Everything outlined above is quite easy to understand.
To obtain ultimate precision, balance noise against speed, let SPICE
perform some maths, draw your conclusions and listen - that's it.
It may sound unbelievable from today's knowledge about human hearing
ability, though to me there seems to be even further room for audible
improvement in timing.
But never mind, if you are already happy with what you have - don't
worry about all that jitter hype above!
If you are already looking for something better and you'd like to give
it a try - you always can ask for PCB boards
that will become readily available soon.
If you have suggestions or found a way to do any better I'd be happy,
if you dropped me a line.
Keep swingin' !
Austria, in January 2007