Moving into the digital domain - Wadax, The Ultimate
I have been absent from AE's forum for quite some time now, however, I regularly paid visits to AE's showroom whenever PT asked me to hear his latest products or tweaks and give my N-B-S feedback.
If my memory serves me correctly, PT has been using LPs as the primary source to do demos and the resident phono amp which he used in last 2 years or about is the Wadax, a 'digital' devise which I think was designed to serve as a DAC, phono amp and it has other functionality too as well, so I was told. Numerous users' reports on the Wadax had been posted in the forum, so I have no intention of following others here.
Let me digress a bit with the aim to let others understand my pride and prejudice in hi-fi. People who knew me know (punt intended) I am no Hugh Hefner in the audio world as Marvel continues to rein supreme to retain this title year after year. I remain loyal (is there other better word) to the equipments I have chosen and these usually keep me satisfied for quite some time (3-6 years) and my attention is on how to improve the playback of my proud system. The meaning of proud is used/expressed in the context of extreme satisfaction, this feeling (very abstract indeed) is derived and then confirmed after auditioning other systems/equipments in different places (however, AE showroom has been my primary playing field for serious comparison) as no other place I know of offers a better sound reproduction (please let me know if you disagree with me), perhaps in my own ground for digital replay.
The above introduction sums up the criteria I use to evaluate other systems & equipments. Next, a genuine audiophile's listening bias must be clearly stated so that readers can understand the listener's impression/feedback of a particular accessory, equipment or system. As a lover of live classical music, I have spent countless hours of tweaking my system to reproduce the sound of a live event in a concert hall or a live recording in the studio – those who come to my place would be shocked (trust me, I am not joking - PT, it's time for you to pay homage to my home) how life-like digital playback can reach such level of realism in a domestic environment. My hi-fi mentor Franck Tchang of ASI fame came to audition my system a few days ago and said I should tell folks not to play music in their home for 2 days after hearing my system because of its realism and awesome dynamics. I am a firm believer once you have chosen the right equipment, the next big challenge is to make your gear sing by correct speaker positioning and room acoustics, the latter is the most important factor. I believe my listening room has very good room acoustics as compared to other places – even AE's showroom is far from perfect, there is a lack of low level bass reproduction and bass slam which I know the equipment is perfectly capable of doing so.
Once you have achieved a lively sound, musicality is the next step to die for. Musicality as opposed to hi-fi means you are hearing the correct tonality, natural timbre, right timing, rich harmonics, harmonic decay and dynamics ..... these are so abundantly audible in a live concert or recording studio. Once your system can reproduce sound with this kind of realism, therefore, in the grand scheme of things, then, why would you bother yourself with constant change of equipment(s) ? In my opinion, the word upgrade has been incorrectly used in the hi-fi world, those suckers tell their hi-fi buddies they have just upgraded to a new hi-fi toy. The point I'm trying to make is the so-called upgrade to an inexperienced audiophile may not necessarily mean better sound to learned hi-fi enthusiasts, period.
To summarise, I am very satisfied with the sound of my present system and have not felt the need to change any of my component, however. I wish to share with you my latest encounter on LP playback using digital filtering at AE just the other day. PT WhatsApp me to visit his showroom, as usual, I obliged as over the years, the improvements I had achieved at home were results of the many painstaking tweaks I made after hearing the superb sound there.
When I arrived, PT informed me he is using the latest flagship Wadax DAC/PHONO combo. I have listened to the Wadax umpteenth time in the past and my prejudice kept reminding me whilst one has to come to terms with digital DAC for CD playback as the world keeps on revolving and digital will become better than valve filtering . However, since LPs in their heydays were recorded using valve equipments and in order to hear the RCA, Philips, Decca, EMI, Columbia & DG recordings properly, you'll need a very good valve phono amp in the reproduction chain.
This fixed belief continues. Although I have listened to the Wadax phono/DAC numerous times and admired how a digital phono can sound this good, as it sounded better than all transistor amps I have heard and rivalling many valve components too, I was never 100% won over by this component because of its tonality or simply put, its sonic character of a very slight dark tonal signature – once you notice this, you can not concentrate fully in the recorded music.
This time, PT introduced his flagship digital playback, the model 'Ultimate', a 2-box design with a pretty flat power supply atop the main component, I think the chassis is exactly same as the previous one. PT immediately asked me to take out the LPs I had brought, I handed him the La Folia which I always listened to at AE. When the first sound of the Spanish guitar came on, whow, it sounded very different to the sound I had heard using the previous Wadax, it sounded most realistic to my ears of a Spanish guitar with nylon strings, it had the right pitch, speed of attack and the correct tonality with the highest degree of realism... I could hear more musical information which was hitherto not noticeable. I was shaken and at the same time, excited.
Next, PT demo the Dire Straits' Private Investigation, the guitar sounded better than before and so was the speed, however, I had slight reservation on the dynamics and bass slam which were not as good as before (may be this is a compromise I said to myself). I told PT my initial impression. He then smiled and said he had switched the previous output setting of the phono section from 5 volts to one volt, he quickly reverted to the old setting and played the same track, lo and behold, the previous impressive dynamics were restored. I then took out the RCA's Mozart no. 4 violin concerto performed by Heifetz, the Dolphin sounded very very lifelike, just like a long time ago when I heard the same violin was played in the hands of Akiko Sumanai when she performed Mozart violin concerto no. 5 many moons ago at the H.K. Cultural Centre. I asked PT to play the Weavers' record I lent to him, we listened to Guantanamera, the vocals of Pete Seeger & Ronnie Gilbert were the most palpable I had ever heard. After a short pause, PT played the Nathan Milstein violin sonata accompanied by piano, the sound of the violin was very very lifelike..... in the end, I was totally bowed over by the sound of the Ultimate, perhaps 'capitulation' would be the most appropriate word to use here.
After the demo, I went home to do a fair bit of soul searching to confirm my listening experience, I did the unthinkable of placing an order for the 'Ultimate' as I concluded living in hi-fi ecstasy is much much more preferable to living in hi-fi denial. Moving closer to hi fi nirvana is the goal of all serious audiophile, right.
At this juncture, there are still many incomplete conclusions in my decision. First and foremost, how does the DAC part of the Ultimate fare with the Zanden, I won't know until I have a direct A/B comparison at home in the future, I did have a very brief listening to the CD replay via the Wadax server, however, the LP reproduction alone was more than good enough to my ears, so if the DAC replay is also better, then this will be a great big bonus.
In closing, I am happy with my latest decision, as in order to better yourself in life, one has to think outside the box, move out of your comfort zone and constantly checking and challenging your fixed belief. The Ultimate is a great find for me. It delivers, to my ears, all the important criteria in sound reproduction I have described above. It has a natural tonality, natural timbre, timing, speed, rich harmonics, harmonic decay and dynamics. The Ultimate is a great find for me, as without PT's recommendation I would not have done what I had done today.
Happy listening in 2014 !
If my memory serves me correctly, PT has been using LPs as the primary source to do demos and the resident phono amp which he used in last 2 years or about is the Wadax, a 'digital' devise which I think was designed to serve as a DAC, phono amp and it has other functionality too as well, so I was told. Numerous users' reports on the Wadax had been posted in the forum, so I have no intention of following others here.
Let me digress a bit with the aim to let others understand my pride and prejudice in hi-fi. People who knew me know (punt intended) I am no Hugh Hefner in the audio world as Marvel continues to rein supreme to retain this title year after year. I remain loyal (is there other better word) to the equipments I have chosen and these usually keep me satisfied for quite some time (3-6 years) and my attention is on how to improve the playback of my proud system. The meaning of proud is used/expressed in the context of extreme satisfaction, this feeling (very abstract indeed) is derived and then confirmed after auditioning other systems/equipments in different places (however, AE showroom has been my primary playing field for serious comparison) as no other place I know of offers a better sound reproduction (please let me know if you disagree with me), perhaps in my own ground for digital replay.
The above introduction sums up the criteria I use to evaluate other systems & equipments. Next, a genuine audiophile's listening bias must be clearly stated so that readers can understand the listener's impression/feedback of a particular accessory, equipment or system. As a lover of live classical music, I have spent countless hours of tweaking my system to reproduce the sound of a live event in a concert hall or a live recording in the studio – those who come to my place would be shocked (trust me, I am not joking - PT, it's time for you to pay homage to my home) how life-like digital playback can reach such level of realism in a domestic environment. My hi-fi mentor Franck Tchang of ASI fame came to audition my system a few days ago and said I should tell folks not to play music in their home for 2 days after hearing my system because of its realism and awesome dynamics. I am a firm believer once you have chosen the right equipment, the next big challenge is to make your gear sing by correct speaker positioning and room acoustics, the latter is the most important factor. I believe my listening room has very good room acoustics as compared to other places – even AE's showroom is far from perfect, there is a lack of low level bass reproduction and bass slam which I know the equipment is perfectly capable of doing so.
Once you have achieved a lively sound, musicality is the next step to die for. Musicality as opposed to hi-fi means you are hearing the correct tonality, natural timbre, right timing, rich harmonics, harmonic decay and dynamics ..... these are so abundantly audible in a live concert or recording studio. Once your system can reproduce sound with this kind of realism, therefore, in the grand scheme of things, then, why would you bother yourself with constant change of equipment(s) ? In my opinion, the word upgrade has been incorrectly used in the hi-fi world, those suckers tell their hi-fi buddies they have just upgraded to a new hi-fi toy. The point I'm trying to make is the so-called upgrade to an inexperienced audiophile may not necessarily mean better sound to learned hi-fi enthusiasts, period.
To summarise, I am very satisfied with the sound of my present system and have not felt the need to change any of my component, however. I wish to share with you my latest encounter on LP playback using digital filtering at AE just the other day. PT WhatsApp me to visit his showroom, as usual, I obliged as over the years, the improvements I had achieved at home were results of the many painstaking tweaks I made after hearing the superb sound there.
When I arrived, PT informed me he is using the latest flagship Wadax DAC/PHONO combo. I have listened to the Wadax umpteenth time in the past and my prejudice kept reminding me whilst one has to come to terms with digital DAC for CD playback as the world keeps on revolving and digital will become better than valve filtering . However, since LPs in their heydays were recorded using valve equipments and in order to hear the RCA, Philips, Decca, EMI, Columbia & DG recordings properly, you'll need a very good valve phono amp in the reproduction chain.
This fixed belief continues. Although I have listened to the Wadax phono/DAC numerous times and admired how a digital phono can sound this good, as it sounded better than all transistor amps I have heard and rivalling many valve components too, I was never 100% won over by this component because of its tonality or simply put, its sonic character of a very slight dark tonal signature – once you notice this, you can not concentrate fully in the recorded music.
This time, PT introduced his flagship digital playback, the model 'Ultimate', a 2-box design with a pretty flat power supply atop the main component, I think the chassis is exactly same as the previous one. PT immediately asked me to take out the LPs I had brought, I handed him the La Folia which I always listened to at AE. When the first sound of the Spanish guitar came on, whow, it sounded very different to the sound I had heard using the previous Wadax, it sounded most realistic to my ears of a Spanish guitar with nylon strings, it had the right pitch, speed of attack and the correct tonality with the highest degree of realism... I could hear more musical information which was hitherto not noticeable. I was shaken and at the same time, excited.
Next, PT demo the Dire Straits' Private Investigation, the guitar sounded better than before and so was the speed, however, I had slight reservation on the dynamics and bass slam which were not as good as before (may be this is a compromise I said to myself). I told PT my initial impression. He then smiled and said he had switched the previous output setting of the phono section from 5 volts to one volt, he quickly reverted to the old setting and played the same track, lo and behold, the previous impressive dynamics were restored. I then took out the RCA's Mozart no. 4 violin concerto performed by Heifetz, the Dolphin sounded very very lifelike, just like a long time ago when I heard the same violin was played in the hands of Akiko Sumanai when she performed Mozart violin concerto no. 5 many moons ago at the H.K. Cultural Centre. I asked PT to play the Weavers' record I lent to him, we listened to Guantanamera, the vocals of Pete Seeger & Ronnie Gilbert were the most palpable I had ever heard. After a short pause, PT played the Nathan Milstein violin sonata accompanied by piano, the sound of the violin was very very lifelike..... in the end, I was totally bowed over by the sound of the Ultimate, perhaps 'capitulation' would be the most appropriate word to use here.
After the demo, I went home to do a fair bit of soul searching to confirm my listening experience, I did the unthinkable of placing an order for the 'Ultimate' as I concluded living in hi-fi ecstasy is much much more preferable to living in hi-fi denial. Moving closer to hi fi nirvana is the goal of all serious audiophile, right.
At this juncture, there are still many incomplete conclusions in my decision. First and foremost, how does the DAC part of the Ultimate fare with the Zanden, I won't know until I have a direct A/B comparison at home in the future, I did have a very brief listening to the CD replay via the Wadax server, however, the LP reproduction alone was more than good enough to my ears, so if the DAC replay is also better, then this will be a great big bonus.
In closing, I am happy with my latest decision, as in order to better yourself in life, one has to think outside the box, move out of your comfort zone and constantly checking and challenging your fixed belief. The Ultimate is a great find for me. It delivers, to my ears, all the important criteria in sound reproduction I have described above. It has a natural tonality, natural timbre, timing, speed, rich harmonics, harmonic decay and dynamics. The Ultimate is a great find for me, as without PT's recommendation I would not have done what I had done today.
Happy listening in 2014 !
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Comments
A well written 'self confession' !! I truly respect your spirit of putting everything right with skills and utmost understanding on what music should mean to you in terms of reproduction via a high fidelity system. In a lot of occasions, I got lost between music and hifi gears and that explains a lot of my zig-zag moves in the past. Believe it or not, I am now more focused and would not easily and blindly go with a 'desire' and take impulsive act.
Wadax has a tremendously flexibilities in the phono compartment and the room correction based on your cartridge and turntable settings is the final step that I would take when the Ultimate Wadax arrives. I have held this exercise back for sometimes since I have installed Kai in my Gabriel waiting for the advent of this Ultimate Wadax. To the hardcore vinyl audiophiles, the CAS portion of Wadax is a bonus. Vice versa, to the digital age, phono is probably something that would open their mind and hearts on countless glorious performances in the vinyl era. To me, I am both and therefore Wadax is just marvelous! Regretably with K15 and Trinity pre, I have not explored enough on the digital attenuation part which I heard what it can sound so wonderfully when PT set it up last year for his open invitation for audition on Track 5, The Dream I dreamed in Les Miserables.
Still, that must be a tremendous surprise to the global exotic audio community of Mr. Zanden going for Wadax Ultimate in the digital domain!
I had a quick visit to AE during lunch today to explore the secret on why Wadax could move Mr Zanden. I listened Wadax Mk2 a few times before. This Ultimate version outperforms the Mk2 in all aspects. The immediate impression of its sound is that it is very relaxing. I don't sense any stress at all on the sound Wadax produces. I don't further talk on areas like tonal density, musicality, details etc. I would only say people will just feel very comfortable with Wadax. Isn't it enough already? What are we looking for all the time? A gear that allow us sit down comfortably and relaxingly to enjoy music. I believe Wadax is the gear! Mr Zanden has made a correct choice and he will be in heaven enjoying music all the time with his Wadax.
This essence is very much needed at present in this world of High End music recreation. Real users that have the sensitivity, the taste and finesse for music and the understanding. Such an alignment of skills mated with the accessibility to try this and that, is very rare. And seeing these among this forum is certainly exciting. PT has certainly done a great job in the dynamics of this natural ecosystem for this to occur.
To my eyes, Mister Zanden’s comments highlight some of the skills I mentioned before: sensitivity, music and understanding.
Paradigm shifts are never easy when there is a considerable associated personal impact behind.
The paradigm shift I am referring to is the digital phono stage and how can a digital core assist analogue sources for better results. By better results I understand better measured performance AND a better listening experience.
Mister Zanden also comments on how he perceived the evolution in the performance of the Wadax phono stage from the Mk2 status to the new Ultimate. The Mk2, is a singular product by itself, was pushed up by several factors. Improvements can be perceived on every front, as they can be measured in multiple ways. Two key technologies team up to raise the bar: First, a new power supply and energy distribution topology and control within critical circuitry has certainly helped here. And second, the Zepto clock.
The Zepto clock: The search for the perfect clock has been a long quest for us and we have come to the end of the road in this area, as we understand it. While our previous clock designs delivered as accurate timing (as it could be possible based on available technology) , our quest showed a few barriers to surpass in order to reach our target specs. Basically we needed to create our clock from scratch, not buying off the shelf modules. All of the shelf modules we encountered are limited in the figures that are critical for audio. We had to start from designing the crystal to special supply and grounding. Two steps that may sound simple but involve using tedious FEA analysis and simulations for growing, cutting, polishing, metallizing, encapsulation, isolation, stabilization and integration. It has been one of the most challenging projects we have ever gone through. Seeking subcontractors with very exotic equipment across the world that had the right tools to apply our ‘different’ approach to clock design. Even new measurement procedures were developed, as available ones had a higher noise floor than the Zepto. We have been able to reach theoretical levels close enough and therefore we believe it is the end of the road for us in clock accuracy for audio applications.
With this post, I also wanted to share some of the passion we put into the design of the Ultimate and the Zepto.
Happy New 2014!
The explanation needs different approximations; physics, signal theory and electrical engineering.
I will try to be as conceptual as possible.
Some prior basics, we all know: Any D/A or A/D circuit requires a clock. This clock is a periodic signal, to be more accurate, a square wave. Any square wave has two edges, a rising and a falling one. The edge is what triggers the conversion to the D/A or A/D.
An ideal clock has edge rising at the same time intervals. However, there are many reasons that make this time intervals to vary. This time interval variation is what we call jitter and the way this time distortion enters the audio stream is also well known to radio engineers (radar design) or very high speed digital design.
The mechanism by which clock jitter enters the audio stream in a D/A (or a digital stream in a A/D) can be characterized by signal theory. 60’s signal theory, by the way: FM and PM modulation.
But jitter is a generic term; it describes a time interval difference between clock edges. But this time interval difference can show a pattern or change randomly. And if there is a pattern, what is this pattern like? A constant frequency? Related to the signal being converted?
So we have another conclusion, jitter generically refer to a deviation from ideal periodic edges but jitter can and do have a character of its own.
Jitter character reacts with the D/A or A/D by the physical and signal theory mechanism of FM/Phase modulation. In this FM/PM modulator, the whole jitter content acts as a modulating signal that changes the content being converted.
FM/PM is a non-linear process. New harmonics are added to the original signal, usually out of phase (not time aligned) so psycho-acoustic effects are specially damaging.
These new harmonics also behave as masking signals for very low level information. This is a very simplified explanation; the real case extends complexity much further.
Some techniques are available to attenuate jitter in a clock. However, the effectiveness of this jitter rejection (or clock cleaning) is bounded to high or mid frequency jitter. Low frequency jitter (
Some techniques are available to attenuate jitter in a clock. However, the effectiveness of this jitter rejection (or clock cleaning) is bounded to high or mid frequency jitter.
Low frequency jitter (
Some techniques are available to attenuate jitter in a clock. However, the effectiveness of this jitter rejection (or clock cleaning) is bounded to high or mid frequency jitter. Low frequency jitter below 100Hz will go straight through the clock cleaners and reach the D/A or A/D clock input. The scene is now setup for perfect contamination via FM.
Jitter is one of the largest contributing agent to digital sound, and clocking is the entry door for jitter. If we analyze Jitter content in frequency domain we can speak of clock phase noise. The lower phase noise, the better the clock will be.
The best off-the-shelf clocks show phase noise at -140dBc/Hz at 100Hz. Just a figure: the Zepto clock measures -190dBc/Hz at 100Hz.
This is on the edge of Natural thermal electron vibration of the crystal and as low as it can be from a theoretical point of view. Other sources of noises inherent to the material also show up at this level.
And of course, power supply work (noise in the power supply converts to phase noise at the clock output), mechanical stability and isolation (a crystal is a mechanical device!), temperature and structural variations (which increases ultra low frequency excess-noise) and many others must all be taken care of at the same time.
But Jeff, as you suggest, what counts is.. how does it sound?
New low level information appears. Instruments, voices, complex passages are all much more defined; improvements in midrange density and bass resolution. Thinner and more focused. Faster (more natural) attacks. Air and atmosphere is enhanced. Blacker blacks. In essence, the aspects we really like from analog.
We summarize this by the term ‘emotional transfer’.
Jitter adds a type of distortion to the audio signal that is not found in nature.
Psycho-acoustically, when we listen, our brain is permanently working to decode and correlate what is hearing and understand it. With the presence of time distortion, decoding is much more complex, and a considerable effort is placed into this reconstruction.
At the end we spend time working to reconstruct, when we should be enjoying. Like in a live performance.
Thanks for such profound technical explanation of the clock. I have never heard of any manufacturer invested in designing a clock. Everyone takes off-the-shelf clock (which is not necessarily bad) and combines it with their circuitry.
For sure, the clock is important but the relationship between the clock and the DA and how the circuitry is designed and execuited also matters tremendously.
How does the zepto clock fits to the grand scheme of circuitry?
I have to say the Wadax Mark 2 is already really something that is unique. It is unbelievable that a digital phono stage can sound so analogue. I have not heard the Ultimate but given Mr.Zanden's sacred decision to change camp is already an endorsement.
I shall have an open mind. AE is a place for extremists. But we may ask more tough questions, if you don't mind.
Do I have an open mind? Frankly speaking, I didn’t. The fixed pure analogue belief dominates. The pianism of Maria Joao Pires at her younger age was captured extremely well by a set of Mozart Piano Sonata by DENON. I knew the whole sonata upside down since many years ago. I asked PT to play Piano Sonata No.11 K331.
PT is particularly proud of piano reproduction all the time since the Tidal Sunray days. Clarity, weight, the pitch, the transients, he got them so right all the time, so what is the big deal this round? It may be the so called “emotional transfer” as indicated by Javier that clicks my heart. With the Wadax ultimate phono, I have a much better grasp of Maria Joao Pires’ actual age when the recordings were made because of her spontaneity in articulating the musical intents. That is important because in my opinion this is what Mozart is all about. (Subsequently the spontaneity of Maria has gradually morphed to better control as maturity ages which are apparent in her later recordings). And this is the very first time I can experience this. To compare, the Da Vinci has an extremely rich mid range that somewhat deprives of transient resolution and attack. The Zanden phono is much more neutral than Da Vinci and really I can’t single out any shortcomings after living with it for many years. The “emotional transfer” of Zanden is a kind of “intended mellowness” in comparison to Wadax. Under the Zanden, the age of Maria would have become a few years older, under my subjective interpretation because the speed and attack, though present, do not strike me as “spontaneous”. It is extremely apparent in the final moment – “Turkish March”. With the Ultimate Wadax, the elasticity of each piano key stroke is well felt springing up and down fluently to form beautiful lyrical lines one after another. Frankly speaking, I could not recognize the Ikeda KAI cartridge. I could not comprehend the purity (no hint of white bleaching) and lucidity of lyrical flow would reach such level of realism. The reproduction is simply soulful. This is a priceless experience because how can one travel back in time to witness Maria plays once more in reality? But what I experienced today was fairly close if you guys believe me.
To confirm, I picked the recording that Mr.Zanden also tested and subsequently gave a “very very lifelike comments”. In the string area, Da Vinci reigns was my belief. As soon as Nathan Milstein started playing, all I could feel is his soul of purity. The delivery of emotion through his hallowed violin is melancholic at the broadest sense but punctuated by slight hint of hope of varying scale from time to time. And this is what the Wadax Ultimate differs. With my other phono stages, the big picture was presented well. I don’t think I lose too much here. But the subplot of the musical message is not well developed. The complexity of human emotion is not completely transferred to the listener. I only knew the presence of such hidden emotions until today.
Unlike other visitors who may want to spend time on as many as recordings in a given time, I prefer to focus deep listening on a few recordings that I know well. But the last recording at 1:45pm today was the “Private Investigation” promotional copy by Dire Straits. Even though I am no big fan of British rock, the electrifying dynamics of Mark Knoplfer’s guitar are phenomenal. It is so naturally rendered. I can “see” the whole musical design of this famous track by Mark Knoplfer.
What a day! I kept thinking the spontaneous tone of Maria while walking back to my shop in Hollywood Road. Hopefully, I can sell some pictures to foot the bill of it after Chinese New Year. This is another no-brainer introduced by AE.
PT, I beg you slow down the pace of introducing crazy stuff.
I am aligned with you on the importance of the interface between the clock and the critical circuitry, i.e. D/A.
Some prior comments: Every connector, cable, pcb track, .. show a certain electrical behavior.
Once we propagate signals through these electrical elements and reach the megahertz region, a new electrical parameter should be used. It’s the characteristic impedance.
This new parameter changes with frequency, but until it gets to the gigahertz region, we can consider it more or less constant. Characteristic impedance is related to physical construction (diameters, etc.) and materials used (insulators specially).
This means that cables, connectors, tracks and everything in the signal path should be designed to exhibit the same characteristic impedance. If this is not met, signals sent from the source will bounce at the target and get back to the source and keep bouncing back and forth for a while. At every bounce there will be some losses, so these reflections will die after some time. But they will leave a trace at the receivers end: ringing. And if the signal being transferred is a square wave, signal edges with be blurred with these reflections.
Now let’s move to the clock scenario. An ideal clock sent through unmatched lines, connectors, tracks, etc. will get to the other end blurred, i.e. jittered.
It’s like being in a big empty restaurant with hard walls. We can speak to someone and if he is very close, he will get a very accurate message. However, if the listener moves away to another table, he will get my voice plus the echoes from the surrounding bounced back sometime later, difficulting comprehension.
Ok, so back to circuitry. One could think that transmission issues could all be solved if everything is matched in characteristic impedance. The answer is, it depends. It’s extremely difficult to match impedances in cable to connector interfaces.
Say we have an external clock, housed in its own chassis. An ideal one. The clock generated inside the external chassis needs to travel through cabling and go into connectors, then jump into cables again (the link between chassis), and into connections again. And then distributed inside the DAC until reaching the D/A ic pins. From the external clock core to the DAC IC in target product, the clock signal will need to pass through a minimum of 4 connectors, 1-2ft of cable, tracks. To make things worse, cables act as pickup antennas for RF and have inherent losses (some are non-linear when analyzed in micro-level). These are some of the reasons why we do not believe in external clocks. The clock needs to be in intimate proximity to the D/A and A/D (if there is one, of course).
But I also need to clarify: external clocks can improve the built-in clock in a DAC. The amount of improvement depends on how good the built-in one is..
Bottom line: External clocks are limited in performance due to interfacing issues.
Ok, so going back to clock tree implementation inside a product and our approach in the Ultimate. First recipe: beside proper engineering practices explained above, we have designed our own discrete clock drivers. We deal with clock in the analog domain. This is the only way –we have found- to distribute clock with no measurable degradation.
All clock distribution chips we have measured ruin original Zepto performance that was so hard for us to achieve. So we had to work on this from scratch and develop the clock tree tools that are consistent with the level of accuracy of the Zepto.
And no worry for any possible tough questions you mention, I would try to do my best if that is the case.
I also had the chance to see Maria Joao Pires performing in London a few weeks ago at the Royal Albert Hall. The skills that have always impressed me about her, were present.. the way she ‘dances’ around the piano while keeping delicacy and expressiveness.
Mozart’s The Marriage of Figaro, Beethoven’s Piano Concerto No.3 and Eroica.
A remarkable experience.
My poison was the the Wadax Ultimate's playback of computer audio and CD. While everyone is raving about what a ground breaking phono stage the Wadax is, they fail to realize that its computer audio and CD playback is also ground breaking.
The Wadax Hermes Digital Streaming option comes with its own beautifully designed server. It has 2 bays that accepts a SSD drive. I currently have 2 SSD drives installed for a total of 1.5TB of space. Javier tells me that the server's capacity is only limited by the size of the SSD drives available.
I currently have about 5500 CDs ripped to FLAC on the server. You can rip your CDs yourself (or use a service) I did it myself over a couple of months on my desktop and copied it over my home network to the server. I've also stopped buying CDs and I'm now a big fan of HDTracks, buying high definition audiophile quality digital downloads.
So how does it sound? Frankly, its amazing! Deadly quiet and very refined!
I don't want to discount its vinyl playback, but to my ears, the digital computer audio playback comes CLOSE to its vinyl playback! Of course I am not using the exotic vinyl gear as the AE-philes on this fofrum (Thales TTT + Simplicity + Kai)!
To me the greatest advantage is I have access to each of the 5500 albums on the Wadax IPAD app, I can create a playlist, and playback at a sound quality almost equal to vinyl playblack!
Javier, do both vinyl and computer audio and CD go through the same digital processing?