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Zero One Ti48 HDD archive & Ar38 Digital - Analogue Converter

Is This The Future of Domestic Audio?

[Zero One Ti48]
[Italian version]

Product 1: Zero One Ti48 HDD Archive
Price: $2,480.00 plus shipping, customs duty and local taxes
Product 2: Zero One Ar38 DAC
Price: US$1,480.00 plus shipping, customs duty and local taxes
Manufacturer: Zero One - UK
Mains leads: as supplied
Digital interconnect: as supplied
Reviewer: Mark Wheeler - TNT UK
Reviewed: February-April, 2005

It is my belief that hard drives could be the future of domestic audio. They've been in the wings long enough for early adopters to have little interest in HDCD, SACD & DVD-A, knowing the future lies elsewhere. It is time the music industry woke up & smelled the coffee. When my sons (aged 10 &12) talk about & listen to music with their friends they don't think about cd or even radio first, they go online & download sample tracks. Those dinosaurs among us who still subscribe to portable hard-software (lp & cd) are not in the buying public the music industry wants to reach. Face it, if an artist as revered & successful as Mavis Staples (of the legendary Staples Singers) had to fund her own 2005 lp, because not one record company was interested, because those record companies only want fast-buck-Beyonces among their female artistes, they'd better wake up to new methods of delivery. The cd buying public doesn't want the cds they want to sell, my children's friends only download, they never buy recorded music as cd, lp or tape. In a very few years cd buyers will be in less of a minority than lp buyers are now. The music biz needs to pay attention to this new market rather than the R.I.A.A. trying to sue 400 students across 18 US college campuses for filesharing; most will pay a little for quick downloads but some of us will pay extra for premium quality downloads.

Hard drives look like the next viable hifi storage medium. DVD-R have not replaced VHS recorders for time shifting TV programmes, those who have replaced their VCRs for this purpose now buy hard drives, DVD-R are bought by those wishing to duplicate DVDs.

"What has this to do with high quality stereo?" demand plebs, stage left
"Absolutely everything", replieth the scribe, "user fine-tuning is back, big stylee!"

One of the shortcomings of cd for the inveterate tweaker is the limit to the diversity and degree to which users may fine-tune the output compared to lp. Vinyl playback allows cartridge electrical-loading changes, tracking force, bias variation, arm-damping, cartridge alignment, not to mention different cartridge bolts, suspension tuning and the dreaded VTA. Upsampling & oversampling are about all that's available from most cd. The changes we hear from them may be as much due to the algorithms involved as to the sampling rates themselves and provide limited scope for the tweaker.

Hard drives loaded with raw data at audiophile sampling rates could be as much a boon to hifi enthusiasts as buying 2nd generation mastertape dupes used to be. Audio casualties like the TNT community would be willing to pay extra for higher sampling rates and longer word-lengths for direct downloads of our favourite music, while the majority prefer the speed and low cost of compressed formats like MP3.

This can only happen once we are all equipped with audiophile quality memory. Indeed, as schoolboys loitering in 70s hifi shops, the first time we discussed sampling audio into a digital datastream it was without any idea of committing this datastream to anything as primitive as tape or silver disc, but storage in computer memory, as was already being described in the electronic journals of the day. Today we live in that future predicted in the 70s even if we're not wearing lurex suits, substituting pills for meals, or travelling by teleport, as was also predicted.

The fledgling audio hard drive market already seems to be split between two target consumer groups. Some are marketed at lifestyle multiroom solutions, where a central hard drive may serve to several rooms in one house. Linn's Kivor hard-drive is sold with key audio features like "Knekt Kivor is a pitch-accurate hard-drive based concurrent archive and retrieval system". But it is also merely one element of a lifestyle range whose marketing thrust is not directed at the Real Stereo community: "The KIVOR TUNBOKS is the ultimate source product...and can be concurrently accessed by up to 16 users."; "simultaneous access...interface with Linn KNEKT system...third party control via RS 232 and Ethernet" boast the lifestyle suppliers of new Linn to yachts & loft spaces. However, the Zero One Ti48 archive boasts features we might expect from a product aimed at hobby audiophiles.

The Ti48 falls into the other hard-drive market, intended as an archive enabling easy access to a large music collection without repeated trips to a storage cupboard filled with little plastic discs each offering less than an hour of music each in most. The multiroom scene has little of interest to the Real Stereo enthusiasts who populate this webzine, but the archive concept will enable us to become couch potatoes of the highest order.

How often have you been gradually mellowing, in your bathrobe, enjoying a bottle of wine, listening late at night to a particular artist reach the end of one album...then silence? You realise you will have to lever yourself out of the chair to seek another disc by the same artist, only to remember it is in the cd-changer in your car locked outside.

If you are unfamiliar with this scenario you are clearly not sybaritic enough for this page!

The Zero One Ti48 hard-drive (& cd transport) and AR38 DAC are impressive, massively constructed silver fronted behemoths reminiscent of stuff like Accuphase and Musical Fidelity. They arrived from Singapore as the first samples in Europe encased in superb packaging. Pricing for markets in North America, Western Europe, Japan, Australia and New Zealand is in $US, a total of $3960 for the pair (plus shipping & taxes). Zero One currently intend to sell direct with a 30 day home trial warranty, in addition to 12months guarantee. Expensive tweaky accessories are already being sold this way. For other markets such as the rest of Asia, Zero One anticipate dealerships in major cities. I live near a city of a quarter of a million inhabitants which has not been able to sustain a real hifi shop for more than 10 years; a shop will open & close again after less than 2 years. The serious stereo community might now be only large enough to sustain a critical mass by Internet and mail order.

The Zero One hard drive & DAC arrive in two enormous packages to protect them from the rigours of international shipping. These cardboard monoliths contain substantial mass, stick a circle of these boxes in a field and expect to find Druids worshipping there at sunrise. Everything you need to get started lies within, including the batteries for the remote control and a set of basic quality leads, including the I^2S interface.

Users are faced with a 10mm thick milled aluminium front centre-panel flanked by 5mm thick side-panels, reminiscent of Musical Fidelity X-series on steroids. The milled finish implies craftsmanship rather than production line, and I hope this individuality stays throughout production. The sides and back are folded & powder-coated, not the clangy biscuit tins regular readers know I hate. The base panel benefits from constrained layer damping too. The instructions impune users not to obscure any of the cooling holes and the class-A output stage of the DAC will inevitably run hot whether idling or playing as class-A demands constant high standing current to maintain its operating point, indeed they tend to be hottest when passing no signal for hours. This limits experiments with pucks and case dampers, my trusty brick-on Isonodes would work where space permits, but is aesthetically questionable and the Jade IsoDuo (reviewed in part 6 of the saga) might also help where space is limited. The knuckle-rap test produced a minor improvement when thus loaded so this is how I begin the test.

Zero One Ti48 Archival Transport Techie stuff

The Ti48 is described as an "upsampling archival CD Transport" capable of storing over 350 hours of uncompressed audio in 240Gb hard disk drive (HDD). But it does much more than just store red book data from your cd collection. The Ti48 is superficially a PC running on Linux OS Zero One custom software, but attention to detail makes this comparison as useful as describing my Ducati as a bike. The sound card is shielded in its own box, mounted on custom isolation and powered from its own very low-noise, linear, opto-isolated, regulated 5v supply, shielded from the main switch-mode PSU. The 5v line even has a shielded cable. This level of attention to isolation would seem to me to be worthwhile as regular readers can guess.

The sound card is only used to extract the digital audio from either the DVD-ROM or HDDs. From the sound card, the signal is sent via the Zero One custom 24/192 I^2S cable to the DAC. I^2S is a Philips proprietary data transmission protocol, also used by Accuphase whose implementation is rumoured to use a shared clock. Zero One's separate clock technology should enable a genuine 24bit 192kHz transmission by interleaving two 24bit 96kHz channels. It may seem strange for a start-up company to adopt an uncommon interface standard in its first product, but it gives them absolute design freedom to optimise every link in the data chain to match their particular needs rather than bodge to fit existing audio technology. The I^2S output is supplemented by a S/PDIF coaxial (RCA) and a TOSLink optical inputs & outputs but these would prevent use of the Ti48 features that make it unique, so they're superfluous.

The custom software uses Linux as the operating system. Again, this is a brave decision given the ubiquity of Windows platforms and and Windows Media, but Zero One decided to write their own software to ensure that there are no crashes and other non-audio problems, familiar to all of us who use Windows.

[Zero One Ti48 display]

The digital filter choices, up/over-sampling and other audio functions are selectable with simple menus from the easy-to-read bright blue alphanumeric display legends reproduced here. These options are computed with 64-bit floating point maths, which is big-style processing capability more familiar in mainframe than pc environments. I suspect this processing power could go some way to ameliorate some of the criticisms, principally of potentially jitter prone, of non-integer upsampling (48.1kHz, 96kHz, 192kHz), figures that have no relationship with red-book cd, but with other digital audio applications dating back to DAT (Digital Audio Tape). The Ti48 also offers 2x (thus 88.2kHz) and 4x (thus 176kHz) oversampling, which will enable direct comparison of these rival approaches, with all other variables controlled.

Regular readers are aware of my obsession with construction integrity & vibration isolation so the low-resonance case, with a constrained layer damped base, comprising two sheets of different thickness metals sandwiching a compliant foam, score credibility points with this reviewer. The HDDs and DVD-ROM drive are all mounted on rubber grommets and the HD mounting bracket is itself compliantly-damped. Excellent, but the feet are horrible hard plastic and one of them is even loose.

The Ti48 is optimised for quiet running using ultra-quiet switch-mode PSU for the PC components, a cooling fan that is much quieter than a pc, and virtually inaudible from 1 metre. The simple alpha-numeric screen displays four lines of menu text with all functions available by the simple familiar DVD style remote-control, which avoids the extra junk (mouse & screen) of pc based music sources that demand space.

Transport is a Toshiba DVD-ROM drive that is mechanically strengthened by Zero One. The the buffered input for the DVD-ROM + motherboard was found by Zero One to perform better for error correction & jitter than audio cd drives and it permits more computing power using an off-the-shelf chip.

The custom software permits a whole bunch of output options, in addition sampling rate selection, to tailor the flavour to suit listener taste and match recordings. Filter rates are selectable, ranging through five options from the familiar red-book "brick wall" down to no filter at all. The options are denoted:

  1. None no filter at all with risk of ringing, parasitic excitement, rf instability of power amplifiers, especially global-feedback types.
  2. HQ1 red-book brick wall standard
  3. HQ2 same corner frequency but less steep than brick wall
  4. HQ3 same corner frequency but quite gentle linear filter
  5. Purist compound filter comprising gentle slope at same corner frequency then brick wall way outside audio band

Dither, or noise shaping, is also selectable. This is particularly welcome to analogue lovers, as much of the individual character of analogue systems may be attributable to the particular way the signal diminishes into the system noise floor. Psychoacoustic analysis has demonstrated that our perception of noise is neither linear nor constant. Our ability to detect wanted information from noise is context dependent and continuously revised by each passing stimulus. A visual analogy might be the random noise artefacts in digital imaging and their more obvious nature caused by the similarity of each defect, compared with dissimilar dust marks on the surface of a traditional silver-gelatine print. Likewise the moire patterns caused by fine textures resonating with the sensor chip construction are more distracting than the random grain-clusters of silver halides in a negative or transparency. Both these problems are easily fixed in digital imaging using dithered noise that reintroduces a base-line of chaos that is less distracting to our gestalt-seeking order-imposing minds. The opportunity to compare the effects different orders of dithered noise means playtime for audiophiles.

  1. None no added noise
  2. TPDF triangular PDF dither added
  3. Nshape high-passed dither at the Nyquist limit
  4. Nyquist second-order noise shaping

The Dithered noise options would only have any potential benefit when the Ti48 is connected to a DAC that is capable of accepting greater than 16bit wordlength. Whatever the conversion chipset, the receiver chips may truncate to 16bit maximum. The Ar38 can accept data up to 24bit and I assume that the Ti48 Archive will usually be partnered with the Ar38 DAC to enable the benefits of their I^2S interface. The wordlength options of 16bit; 18bit; 20bit; 24bit are rendered redundant by the dither options. Unless you use the Ti48 to test DACs from other manufacturers where 16bit would be necessary, I can imagine no circumstances when users will select anything but 24bit and then fine-tune with dither.

A crude analogy of the the dithered noise contribution would be to imagine it fills in the gaps below the least significant signal bit, thus enabling complete detection of that data present. This will have the effect of swamping those artefacts that are analogous to the moire patterns in digital imaging.

Zero One did consider making output preferences programmable for each track, but decided this might make the whole archive process too clunky for most users. Given that some audiophiles are anally-retentive enough to note VTA settings on their lp inner-sleeves, I have suggested to Alvin that this might be a popular feature on a future model.

I asked whether a vinyl input might be a future idea to enable us to archive our precious collections and was told that this has already been considered, but R&D will only begin if customer demand is shown to exist. In order to encode an LP at 24 bits/96 k which is the minimum Zero One believe is required, HDs of really large capacity eg.500gb will be needed. Such beasts are not currently quiet enough for audio use. Although Analogue-Digital encoding could include options for cleaning noise from lp or analogue tape, and such software is available currently for LP archiving, any filter subtly changes the encoded music from the original LP. If an lp archive facility were offered Zero One would prefer to minimise signal processing, which I find encouraging.

Those with big vinyl collections of material not available on cd or only available on inferior cd transfers should make suitable offerings to their deities to bring forth this manna. This information came from a personal briefing from designer Alvin Heng and is not yet available on the Zero One website or in their literature so we can only guess when it will be available to consumers.

Alvin also believes that high quality downloads are a long-way into the future, although I am more optimistic. This should be the future of domestic audio as soon as the record companies remove their collective heads from their collective backsides. Alvin correctly notes that the world will need an infrastructure of higher-speed broadband connections (perhaps ADSL2), that actually work (my modem & ISP are set at 1.1Mbps but it behaves like about 350kbps because of the ancient telephony infrastructure), but this will happen for other reasons anyway. Alvin doesn't "think it will get beyond 16/44.1 for quite a while, maybe a decade or more. [he] doubts there would be significant demand for 24/96 quality music downloads." Perhaps the companies that manage to make a profit from 180gm vinyl reissues will find a profitable new niche offering this service to sufferers of audiophilia nervosa.

[Zero One Ar38]

Ar38 DAC Techie Stuff

The Ar38 DAC sports cool blue LEDs and accepts digital inputs from either co-ax sp/dif or the Zero One I^2S from the Ti48. The I^2S link can receive up to 24 bits/192 kHz from the Ti48. The sp/dif input allows upsampling other digital sources to 24 bits/96kHz. It also features a low resonance aluminium case with compliantly-damped base.

The Ar38 is described as fully dual mono, with discrete class A circuits without any global feedback. The analogue stages are direct coupled meaning no series capacitors in the signal path, with important benefits in transparency & group delay, especially at low frequencies. Full marks to the tech-spec, they've covered every audiophile preference and allowed choices of every parameter where no hegemony exists.

The output is fixed, Alvin Heng dislikes digital volume controls and believes the analogue volume control belongs in a good preamp where there is less electronic noise and more appropriate power supplies, like the integrated amplifier Zero One are currently developing. My experience with the Shanling is that the volume control is slightly more transparent than a pre-amp when used with the valve buffer direct to a power-amp, but that attenuation in the pre-amp is better than from the direct solid-state feed.

The Ti48 & Ar38 digital processing follows the current hegemony of Burr Brown & Crystal; and the DAC is a BB PCM1704 multi-bit Digital-analogue-converter. The high accuracy custom-made TCXO clock should enable these established chips to perform to their optimum. SP/DIF and I^2S inputs are handled differently: in I^2S mode the Ti48 feeds digital data direct to the Burr Brown PCM1704 DAC to minimise jitter. The SP/DIF input is upsampled by the ubiquitous Crystal CS8420 chip and is fed to the Burr Brown PCM1704 DAC via the Burr Brown DF1704 receiver. Received wisdom is that these are the current cream of the processors crop, and they appear in most products with any pretension to high end cd replay.

[Zero One Ar38 rearpanel]

In Use

This pair is comparable in size & weight to my Michell Gyro SE/Hadcock/Naim front end and this is the benchmark by which it is judged, although the currently weak US dollar makes the Zero One combo rather less expensive than that vinyl spinner. Think of the Ti48 as the turntable/arm and the DAC as equivalent to the cartridge/phonostage. The comparisons are even more relevant when one considers the tweakery available to fine-tuners of vinyl playback which is equally user involving on the Ti48. It has over 40 user-selectable playback combinations of up&oversampling, digital filters and dithered noise. Even VTA twiddlers will find enough to get paranoid about with the Ti48, endlessly worrying whether this song is better with the "Purist filter" or the "HQ1 filter" or the "HQ3 filter", at 88kHz or 176kHz or...etc, etc. It also has to compete with direct cd replay from its own drive, also with these options. Phew!

The Ti48 & Ar38 Could do with some front panel operation for losers of remotes, a menu button, scrollers & enter would be enough. Better still would be a modest little touch screen as seen on the Classe Deltas. The remote control will be familiar to anyone who owns a television or dvd player. It's a generic plastic thing weighing just 125g (including 35g batteries) and looks & feels really cheap next to the extruded aluminium 225g Shanling CDT100c remote. Pride & pleasure of ownership would be greatly enhanced by a more tactile remote control as it is the principal interface between owner & product.

Maximum gripe is also with this horrible plastic remote control. A single press of its buttons often scrolls through two functions or flips to a function and back again in a single stroke. Furthermore, the play-pause-stop buttons sometimes do no such thing while listening to the hard drive. Trying to jump one track or rewind part of a song often results in chaos. The functions are fairly straightforward but the learning process is impeded by action being unrewarded by the desired result. The double jumps are particularly frustrating when users notice that the alpha-numeric keypad is of the mobile-phone variety that requires multiple strokes of one key to reach the desired letter and this will be an essential tool when users have over 100 cds archived. The alphanumeric pad was better than the "menu" & "OPTS" buttons but I have no confidence that it will work correctly anytime I pick it up. No matter how the Ti48 performs I could not live with it if this remote control remains part of the package.

If this seems petty, remember that the remote control is the user's only interaction with the Ti48 once the cd has been uploaded. Placing a cd in the drawer is the only other activity in the user interface, and even that action requires the remote to "open" and "close" the drawer. This is a US$4k purchase of a new source including interconnects and a dysfunctional remote control does not belong at this elevated price-point. Every visitor, especially style conscious women, who encountered the Zero One combo commented on the cheap light remote control and how it doesn't belong with such a product.

The "quick start" section of the instructions runs to 13 pages! Owners will be on a steep learning curve from the outset. Plus, there are programme paths integrated into the system that are not yet available but will become available later purchased as hardware upgrades or available online. This level of future proofing will be a boon to those of us resistant to new technology purchases.

Listening

It is actually much easier to use the Ti48 than the foregoing paragraphs imply, apart from the quirky remote control. I suffered a brain-injury in a motorcycle accident that makes it difficult for me to learn new processes & sequences, so if I can do it so can you. From cd directly on the default settings the sound is good, comparable to cd players in the US$3k territory. The soundstage not quite as big & sensuous as the Shanling CDT100c valve buffered output, but it is wider & deeper than my hotrod Rotel RCD965BX discrete, that has more BlackGates than a prison and much bigger than the Avondale AAA5. Pace is good, but rhythm & timing not quite as good as the Naim beating Avondale AAA5.

The perceived noisefloor does seem much lower than any other player I have heard. This may be a psychoacoustical phenomenon as much as S/N (signal to noise ratio) specification. This applies whether or not dithered noise is selected. The ambient noise in my room and the broadband noise of the modified Assemblage SET300B Signature single-ended valve power amplifier should be high enough to mask whatever noise is produced by these sources (except perhaps the Shanling valve output), but the effect is obvious and repeatable. I am reminded of the effect of removing the Rotel from its clangy steel case and installing it in a Torlyte box. The Zero One attention to vibration isolation and power supply isolation could be responsible for the inky black inter-transient silences achieved in direct cd mode. This bodes well for the quality of data to be retrieved for the hd archive.

I choose my first disc to upload, Jimi Hendrix First Rays of the New Rising Sun, as I have 25 years familiarity with the material which originally appeared over three slabs of vinyl posthumously released in '71 & '72: Rainbow Bridge; The Cry of Love; War Heroes. I have 6 years familiarity with this cd (and its double 180g vinyl equivalent) that hints at musical directions Hendrix was headed at the time of his death. I know this material as well as any so it seems ideal to test an entirely unfamiliar format.

The upload is easy. The playback equally easy. That dismisses any user anxiety engendered by the long instruction manual. As all blokes know, it's better to try the thing before scaring yourself with the instructions.

Then select HD and press play. Superficially the next statement does not make sense:
The Ti48 archive sounds better than the data source (cd) direct.
"What journalistic deceit is this?" demand plebs chorus, stage-left
"I just report what I hear" sayeth ye scribe
"Oh yes? And how many pieces of silver or freebie chattels did the alchemist Alvin promise you?" demand plebs chorus rapidly evolving into angry mob,
"What snake-oil enhanced signal-processed magik is this?" they shout,
"We must rush to the stone circles and make sacred offerings to the druids, for this Ti48 is surely alchemy turning base metals into gold..."
"we must burn him as a witch" they cry, seizing lighted brands from the microwave...

Careful reading of the technical design process provides some clues to the answer. Zero One always intended that the performance of the data retrieved from the hard drives should exceed that possible from the raw data stored on the cd. Such an idea usually implies signal processing of an additive kind that is at best harmless and at worst merely colouration, but Zero One maintain that these improvements are the inevitable consequence of improving the quantity & quality of the data by the simple expedients of reducing losses and improving delivery.

Losses are minimised by sampling and handling at 24bit word-length; the 16bit cd data is often truncated in playback to 14bits (indeed some early players only attempt to retrieve at 14bit), where the wider dynamic window of 24bit capability ensures that whatever is on the disc can reach the hard drives intact. Although these are usually referred to as "least significant bits", this comparative term does not indicate that the lost information is insignificant, merely theoretically less significant. Indeed, this data at the minimum resolution of dynamic range, when returned to the analogue domain, provides the subtlest clues to nuances of performance and ambience that separate a moving recorded performance from a pot-boiler. Allan Wright, doyen of analogue valve design, uses the term "downward dynamic range" to describe these effects, and the Zero One does propel downward dynamic range deeper than the direct cd play. Selecting any word length option lower than 24bit is pointless and my experiments with a Mobile Fidelity Sound Lab cd showed that with good source material the difference becomes audible; 24bit is better.

Playback sampling is now fine tuned by careful selection of sampling-rate either by integer multiplied over-sampling or by the more complex algorithms of upsampling. Playback filter slopes may now be fine tuned to match the needs of the combination of chosen sampling rate & individual disc, where this has often been dictated by choice of hardware in the past. I consistently prefer no filter.

These decisions are in the information retrieval domain and only the option of dithered noise falls into the domain of additive signal processing. The dither combines with these other more fundamental data retrieval factors to minimise the artefacts remaining after fine tuning, much like the extra valve stages added to digital-analogue conversion as long ago as the Cal Tempest and as recently as the Audio Note and Shanling offerings. Legendary Concordant designer Doug Dunlop used to refer to "pheeoow" as the audible sheen applied by a good high-end pre-amp to the signals it handled and the dither control seems to have a similar effect.

The TPDF option has the most dramatic effect, and is particularly useful at creating an illusion of more resolution & clarity at high frequencies on softer sounding recordings, presumably via a sawtooth modulation pattern. Certain classical vocal recordings, like Arvo Part's O Adonai, have a seductive warmth & humanity on the 176kHz setting that is compromised by too much softening of high frequencies on this sampling rate. The TPDF setting works really well at resharpening this sampling rate choice.

The Nshape effect is very subtle. So subtle it is inaudible on many recordings, but it does seem to restore ambient cues on live recordings. It comprises high-passed dither introducing ultrasonic noise at the Nyquist limit of the sampling rate in use, apparently helping to linearise some DACs. The Ar38 clearly does not need this extra help as I could not hear a difference with most recordings.

The Nyquist setting creates second-order noise shaping which is supposed to allow more resolution at low frequencies, at the expense of more noise at higher frequencies. I would have expected this to be the setting to contribute to ambience recovery, but again the effect is really subtle. Zero One note that this is a good choice with sampling rates above 88.2kHz, but I found the cruder TPDF more useful on the soft-focus four-times oversampled 176kHz.

Surprisingly the speakers needed repositioning to fine-tune the best performance from this pair. They required less toe-in but moving about 25cm closer together, to become 2.25m apart at 3m listening distance. the only source component change that has this effect is some pick-up cartridges (the Denon DL103 being a notable example). Once optimised the fun can begin with the various playback tuning options. And it is so much fun. Unlike most tweaks this can be accomplished on-the-fly while listening and without moving from one's favourite chair.

Spookily, the various effects are most similar to pick-up impedance loading changes, or even changes of an entire cartridge. Successful changes of sampling rate and filter slope are reminiscent of lowering the input impedance for a Decca London from 47kohm to 33kohm, which opens up the sound making it more flowing and less mechanical. Despite changes in the digital domain being expected to have more effect at high frequencies, sampling rate changes also affect the bass like raising the input impedance for the Supex (and hence old Linn) moving coils from 100ohm to over 500ohm.

Son (12) thinks treble on Zero One even better than vinyl, but vinyl bass better. There just is not enough information present on a cd to equal the ultimate resolving power of good lps, despite the theoretical advantage of cd for noise, s/n ratio & dynamic range, there is something about the way analogue data stores & retrieves that must be symbiotic with human hearing for its obviously more inaccurate information to be more subjectively satisfying. Perhaps it is the ability to apply a choice of different noise shaping algorithms that enable the Zero One to emulate so successfully the analogue experience. My own professional expertise is in the mind-brain-eye domain where I am aware that the emotional impact of visual experiences cannot be broken down into simple dimensions of content, form & optical qualities; so the analogue vs digital debate seems pointless to me and all that matters is what experience satisfies the individual purchaser. Regardless of the digital-analogue convergence I report here, how many lps can be described as "good?".

On balance, the Zero One Ti48 and Ar38 combination offers one of the best domestic digital playback sources it is my pleasure to enjoy. Added to this is the user involvement of obsessive tweakery that many audiophiles enjoy. It is also possible to set a playlist and enjoy for many hours longer than any conventional source, even radio concerts come to an end sooner than we might want. Any moments of dissatisfaction may be ameliorated by a quick play with the settings. The Zero One combo does not have any outstanding performance area to attract devotees of any particular audio creed but is is not weak in any performance area, unlike so many single-minded audio approaches to nirvana. It can tend toward the relentless pace of pre-Cirkus Linn Sondeks and shares that turntable's bass emphasis centred around 100-150Hz, especially on certain setting combinations . This is a more modest effect on the Zero One combo than the Linn, and sounds like power supply choice on the DAC output stage. It enhances listening most of the time.

Like the best pro-sector products the Zero One Ti48/Ar38 combo does everything well enough; well enough not to be too irritated by operational foibles and well enough to enjoy all day.

Switching on our computers & Playstation does not affect the performance suggesting excellent power supply isolation, even when I tried plugging the playstation into the dedicated audio mains-ring. After many days of enjoyable playback I come to load a new playlist and the operating interface just freezes. I change to the other remote control; I load new batteries and still no joy. So knowing what works with my pc I manually reboot with the rear panel switch and this message appears.

  1. Checking system...
  2. Checking music...

As I am a reviewer I get to email the designer directly, who had believed that when the system experiences an error, if powered down & rebooted it will display this message until it has recovered but this could take up to 1 hour. After several hours this message remains. I repeat the procedure with the same result. He telephoned me for another walk-thru instructional then arranges to have the Ti48 collected.

So this review gets interrupted. This is a new product, using new technology and perhaps early adopters become Beta testers for situations the designers hadn't expected, which should not deter adventurous buyers if back-up service is good; if this type of experience put buyers off there would not be a single pc or Widows o/s in a single home on the planet. Perhaps I just performed "An Illegal Operation" or perhaps a "Fatal Exception Occurred" (but this is Linux OS).

After another long telephone call from Alvin, who was upset that any problem has occurred, I move the Ti48 to repack it and note that there is a distinct sound of something loose. A loose hard drive indeed, caused by the wrong screws being used (the hard drives are US manufactured where they still use non-metric threads, unlike the technically advanced world) and a dry joint on the remote-control receiver connection. I am told that both problems are now rectified in production.

The Ti48 was returned by Alvin's father-in-law and supplied with a new optional I^2S cable to isolate the ground-planes of the Ti48 & Ar38 in a bid to reduce potential noise even further. This is the first available optional extra at $200 and I have one of only two samples in the world so I'd better not break it. After reacquainting myself with the Ti48/Ar38 sound I swapped cables. The new connection breaks ground loops & lowers system noise even further in the digital domain, so I expected differences only to be obvious with no dithered noise. I selected "none", also no filter & 88.2kHz to maximise differences. Even cold & fresh new the cable is better as if more data is preserved & more information presented to the DAC. Surprisingly there is less difference between noise shaping options, which seems counterintuitive. There is still hardly any difference between output filter shapes, and I prefer "None". My system is quite immune to rf problems and the power amplifiers in use are zero-global-feedback, higher feedback designs might be more adversely affected.

The biggest difference is that the Linn-like bass-hump & relentless pace is tamed. Pace, Rhythm & Timing performance is improved to a new coherence that renders Arvo Part's Alina hair raising; it's a piece totally dependent on impeccable piano timing for its tension & power. This is a cruel test only matched in timing by the Avondale (on permanent loan) and I can only wish for an analogue lp of this piece for comparison. The clarity & low-colouration exceeds my hot-rod Rotel benchmark too.

[Vibration control brick]

Vibration Control

Further gains are possible by attention to vibration control, but the solid construction certainly helps. The pace is affected by the support to the drive similar to the effects on cd players. Despite the constrained layer damping of the base the ERaudio SpaceHarmoniser worked well wedged between the hard plastic feet of the Ti48, but had little effect on the AR38 (illustrated). The Polychrystal Reference or Jade IsoDuo feet offer two viable alternatives under the drive, each an order of magnitude better than the Ti48 feet. The DAC is more happy on anything other than its own feet. 4 Jade IsoDuos or 5 Isonodes both working well.

Due to the essential ventilation holes I could not try the Bright Star LittleRocks directly on the top surfaces of either drive or DAC, but I do find a LittleRock 5 perched on Bright Star Isonodes improves clarity slightly. Good support is essential as with any source component.

Conclusion

This has been a steep learning curve for this reviewer. Not only a technology entirely new to me, but also the opportunity to use it to compare the effects of sampling rate changes, filter rate changes, noise shaping & dither through the same chips.
I am tweak-drunk with the exertion.
I am despairing of the nasty remote-control.
I am impressed by the performance.
I am enjoying hours of music interrupted only by the shutdown.

The performance of both these components is impressive. They work very well together and raise domestic digital replay potential to a new level at this mid-market price. It would be possible to get similar quality, and more high-end gloss, from a cd only player at a similar price, but such a purchase would only exceed the Zero One Ti48 & Ar38 performance with the best cds. Where the Zero One products excel is their capacity to make the most of lesser cds.

This combo did not outperform my vinyl front-end, but came surprisingly close.

That the Zero One, despite its operational quirks, gets closer to providing analogue style satisfaction is testament to there being nothing inherently flawed in digital data storage of music (and most analogue lps are recordings of data that has been converted to digital & back somewhere between microphone & laquer) but that it is possible to make better use of even 16bit 44.1kHz data than conventional cd playback. The noise shaping options might provide clues to the way the Ti48 converges digital data with analogue experience.

Whether the time separated functions between cd data retrieval and data playback makes some contribution I do not know. I find it hard to believe that it could be possible for the hard drive reproduction of data from the cd to sound better than the direct output of the cd, but it does; every time. This cuts to the heart of the debates that have raged through the domestic audio community since the late 70s. It is as if two schools of rationalism collide again as they did in the 18th century.

The audiophile descendents of the British Empiricist (Berkely, Hume, Locke etc) branch of Rationalism are locked into ideas that what you hear is what you get regardless of its likelihood, that this is its own form of objectivity founded in the ideas that good science emerges from observation of phenomena followed by attempts to explain those phenomena. Faced off against them are the objectivist descendents of Continental Rationalism (Descartes, et al) who continue to argue that if it can't be explained then it can't be happening, and all else is illusion or delusion. Perhaps the audio community needs an Immanuel Kant of the 21st century to try to reconcile these discourses and explain to me what I am hearing and why I am hearing it. The Ti48 output options do not sound as intuition predicts and the hard-drive does a better job of presenting the data it has retrieved from the cd than the cd itself. Go figure.

Value judgements of the Zero One are impossible because there is nothing in my experience similar to compare. While in my system the Zero One archive/DAC provides some of the most enjoyable listening available from a digital source. It has also all the play value of tweaking from the comfort of my armchair, what more may a sybarite ask?

Music enjoyed during this test:

Jimi Hendrix First rays of the New Rising Sun, MCA MCD11599
Derrin Nauendorf New History, 2005
Sly and Robbie Drum & Bass Strip to the Bone by Howie B Palm Pictures 2004
Pink Floyd Dark Side of the Moon, MFSL
Dave Brubeck Time Out, already archived
Arvo Part Alina, ECM1591
Arvo Part Beatus choral works, Virgin Classics 562 2052

Manufacturer's comment

Firstly, our heartfelt thanks to Mark and to Lucio for such a comprehensive review of our first two products. It is obvious from the effort spent on trying out all the digital processing functions that Mark really did spend a lot of time listening to the Ti48/Ar38 system. Apparently he enjoyed it too, which is a bonus when you have to do work as arduous as audio reviewing.

As this is our first review, of two products that literally were the first to come off the production line, we expected some teething problems - and we got them ! Fortunately, they were relatively minor (wrong screws, poor soldering on a connector) and can easily be (and will be) rectified.
Also, Mark was incorrect when he said that as a privileged reviewer, he was able to email me directly to complain - actually all customers can send me an email to complain (or praise). My email address is given below should you have anything pressing to say right now!
So thanks again to Mark and to TNT for a balanced, positive and very long review!
Alvin Heng - E-mail: a.heng (at) zerooneaudio.com

Copyright 2005 Mark Wheeler - www.tnt-audio.com

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