hord begin their Power Point presentation of the Blu Mk II CD transport with a significant feature called WTA filter tap length history (Chord uses interchangeably terms Mk 2 and Mk II; to simplify it for the purpose of this review I shall use the latter). As for the description of a CD transport it is rather surprising. Chord would not be Chord though, unless they were interested primarily in technical excellence of their device based on applying solid-engineering primarily in the digital domain. The mechanical part, the analog section and the power supply are just as important, but let's not pretend here, the real excitement on Chord guys' faces can be seen when they discuss Robert Watts ideas.

Robert Watts has been the person behind the most important developments of this type at Chord for years many years. He became well-known in 1999 when this English company presented their DAC 64. It was the first Chord's D/A Converter utilizing a Field-Programmable Gate Array - a programmable logic array. It featured an innovative type of digital filter, that is, an element directly followed by a DAC stage. This filter was named: Watts Transient Aligned filter (WTA). The idea was to minimize the so-called pre- and post-ringing.

What is „tap”?

This system was built to reconstruct an original analogue signal based on 1024 registers, so-called "Taps". What is "tap"? As Robert Watts explained in an interview for the-ear.net portal, WTA is a type of interpolation filter. The Whittaker-Shannon's sampling theory says, that one needs an infinite number of registers, ie points between one sample and the other, to obtain a perfect signal mapping, ie to reconstruct an original analogue signal. In the early days, they used a delay line to store the previous data samples, and they tapped into this delay line in order to access the stored data. Hence the word taps.

source: Robert Watts, Rob Watts on Chord Mojo tech, an interview conducted by Jason Kennedy, the-ear.net (accessed on: June 26th 2017)

As Mr. Robert said at the time, to get the perfect sinewave, the number of "taps" should be infinite. In real life this can not be achieved, because the signal would never leave such a system, it would be "tapped" forever. So a reasonable compromise was needed, taking into account the technical capabilities of the systems available at that time. Progress, however, does not tolerate emptiness, so in each subsequent product the number of taps grew:

• 1024 taps – DAC 64 – 1999,
• 18 000 taps – QBD76 – 2008,
• 26 000 taps – Hugo – 2013,
• 164 000 taps – Dave – 2015.

There were 1,015,808 taps in the Blu Mk II transport, which, as Mr. Watts says, is close to infinity from the digital music point of view. This improved WTA system was named the WTA M Scaler and was implemented in a powerful Xilinx XC7A200T. It's a digital chip with 740 DSP cores, 215 360 logical gates and 16 Mb of memory. This system draws 10 A current!

COLIN PRATT
Chord | Sales Manager

WOJCIECH PACUŁA: What are the differences between Blu mkI and II?
COLIN PRATT: The Blu Mk1 featured an upsampler, that allowed us to change sampling frequency from 44.1 to 176.4 kHz, which is four times higher, using a smart, mathematical upsampling algorithm. The new Mk 2 uses a completely new solution featuring FPGAs programmed by Robert Watts, that allow us to upsample 44.1 kHz signal to 705.6 kHz. To use this feature one needs two digital BNC cables feeding signal to BNC 1 and BNC 2 inputs of our D/A Converter DAVE. After one second DAVE registers D/Data transmitters and confirms 705,6 kHz sampling frequency. To achieve that one has to move the upsampling switch on the back to lower position, and the dithering switch to upper position

The Transport features USB input – usually it's a DAC that sports such input, isn't it?
The USB input is active all the time, unless a CD is played. One can connect a source via USB input to Blu Mk 2 Transport to use its upscaler and feed D/A Converter with already decoded PCM or DSD Signal.

What is a sonic advantage of larger number of „taps”?
Each increase of “taps” number along with improved WTA results in better quality sound. There is a better bass definition, larger soundstage, better separation of instruments and focus, also tone of instruments is differentiated in a better way.

Why didn't you use such upscaler in DAVE?
Unfortunately, it wasn't possible because of a peak current FPGA draws, also noisy current would generate distortion and noise in DAVE, by corrupting Dave’s ground plane.

Blu Mk II

The Blu Mk II is primarily a transport, and therefore a mechanical component. Since it has been combined with an upsampler, in Chord's nomenclature "scaler", it is actually an upscaling CD transport. Its full name reads: Blu Mk II M Scaler Technology.

Although over the past few years it seemed that mechanical transports were a dying species, it is now clear that the rumors of its death were exaggerated. Chord has used a well-proven solution, the Philips CD-Pro 2 LF transport, which was also used by other brands in various players such as: Vitus, Audio Research, Ancient Audio, Métronome Technologie, Audionet, Ayon Audio and others. The Blu Mk II actually features a slightly mechanically modified transport. The so-called Philips "kit" includes a transport screwed to a cast plate, decoupled using four springs. Chord preserved the springs (while for example, Ancient Audio got rid of them), but two of them do not support the Philips element, but rather a larger plate to which it is screwed.

It is a top-loader, ie the compact disc is placed directly on the motor axis. The chamber with the plate is closed, as in Vitus and Audio Research models, and earlier in the Chord Red Reference Mk III. Here it has to be closed manually - it is a heavy, milled element, "suspended" on three springs. Unfortunately, this is not an ideal solution because one has to be careful not to close it too hard. Also inserting and removing discs from the compartment is not very comfortable.

The device uses a switched mode power supply - something Chord is known for. Signal can be sent to this transport via USB cable to benefit from the "scaler", but also via S/PDIF cable using BNC input. The device may be placed horizontally or in a special "rack", quite expensive one, that costs 9990 PLN. By combining two such racks one can place the Blu Mk II and DAVE one on top of the other.

The Blu Mk II was tested together with the DAVE DAC. The signal was transmitted with two BNC Synergistic Research CuWAg C.T.S. Digital cables. Both units were powered by Acoustic Revive Power Reference Triple-C power chords with RAS-14 Triple-C filters. Both elements were placed on their racks. As a point of reference, I used the Ancient Audio Player AIR V-edition, Gold Note CD-1000 and Accuphase DP-560.

A two-box Chord CD Player at first glance may seem like an “accidental marriage". The element that made a lot of fuss on the market and that obviously was very important for the company was DAVE digital-to-analog converter. It featured the latest, at the time, version of the WTS digital filter (Watts Transient Aligned) with 164,000 registers (taps), working at 256fs, which means with 264 x sampling rate of the input signal. It also contained a 20-element “Pulse Array” DAC technology with discrete resistors and switching transistors, as well as Chord's own solution, an analog “noise shaper” analogue filter of 2nd order that moves noise outside audible band.

Considering all that, the Blu transport, even in the new Mk II version, may seem like an addition to the “main” product, or even a redundant product. In fact, it is the Blu, the inconspicuous CD transport, that allows DAVE to achieve a new level. Pairing Dave with third party CD transports as well as with media players / file servers, worked really well, but it seems that the Blu Mk II + DAVE are the ultimate solution. As if there was an open slot waiting for the new Chord's transport, which when finally closed executed an additional program.

Blu Mk II + DAVE

The Chord player delivers an extremely focused, deep, dark and resolving sound. This is a high-end performance of a very high level. Its tone, which attracts attention first of all, is thick and dark. The amount of shades within this "darkness", however, is unbelievable. The differences between various types of recordings are presented very clearly, even within one album. This is largely due to outstanding resolution, it's probably clear. The resolution itself without something else, ie something that will take advantage of it, has no meaning, and in extreme cases it can lead to sound being hyper-detailed, which is a curse of our industry.

That's why the fantastic sound quality of the newly remastered Czesław Bartkowski Drums Dream album from the Polish Jazz series (vol. 50) was so obvious. Jacek Gawłowski responsible for this new version apparently has a patent for a good sound or he'd already got familiar enough with Polish Jazz tapes so that he was able to prepare one of the best sounding (so far) albums prepared by Warner Music Poland.

The point is that the dynamics of the percussion is unique, but it does not cover the tone of the kick drum, cymbals, the trumpet sounds also great, even though it is so different sonically, and here it enters a dialogue with drums, with both instruments taking lead one after another. Chord presented this recording in an unusual way, building tension, filling the space not only with direct sound, but also with reverbs.

Right after Bartkowski's album I listened to the Takeshi Inomata Dialogue CD, originally released in 1977 by Japanese Audio Lab. Record label, known for its extremely vigilant approach to sound. Also here drums play a leading role entering dialogue with various instruments. The opening solo was with Chord fantastically dynamic, full and dense. For me, it was even more important, how the English player presented all parties of the dialogue.

There was something of the velvety nature of high quality turntables, such as Kronos Pro MkII (Polish), in it, combined with the effortlessness of analogue master tapes. I have to say that although, in this respect, the two-box CEC player consisting of TL0 3.0 transport and the DA0 3.0 DAC, was even better, sounded even more effortless, the Chord was not so much behind and it was the only player except the CEC I had at home, that showed this property of reel-to-reel tape recorders.

Its tone is rather sweet and somewhat warm. My reference AIR V-edition Ancient Audio player delivered a somewhat simplified performance, with a stronger attack. Chord's attack is a bit softer, more engrossed in sustain, but that's probably the right way, as that's how live music sound like. The lower end and upper treble are absolutely unique. They have density and weight, they are tangible, but never too heavy or too strong. They complement, I think I can say so, the midrange carrying most information.

This is where our attention is focused. And it's more about 'events' than 'sounds'. Listening to Chord, we are well aware that this is a mechanical reproduction of a musical signal, such is the nature of audio devices. But all this mechanics, the machinery behind the recordings is “civilized” by this player. Even if something is not perfect, it becomes its quality, not a disadvantage. Although the differentiation is exceptional and there is no doubt about the differences between such albums as Fleetwood Mac's Tusk and The Velvet Underground's Loaded, when listening we tend to skip these differences while focusing on differences in music. This is something only the best sources are able to offer.

In this case, this is achieved because density and focus are supported by outstanding imaging differentiation. Many times in recent years I have pointed to this shortcoming of many CD players, turntables and virtually all file players. Only the full dCS Vivaldi (Polish) system and the above mentioned CEC, were able to do something that had been a feature of my reference player, said Ancient Audio, for years. So many years ago, in his garage, Jarek Waszczyszyn created a player using only the existing technologies, that in terms of soundstaging competed with the best turntables. In fact, all other sources in comparison sounded flat and one-dimensional.

Until I heard the TechDAS Air Force One, Vivaldi and CEC. And now Chord. It proved that in this respect it belongs to this elite group. I haven't heard so organic, normal, natural space in a long time. I had both, differentiating elements in terms of tone, which changed when the instrument was further away from me (from the microphone) and in terms of volume. This is very difficult to present and only the best source can do that.

The tested system delivers an extremely deep soundstage. The AIR played a little more forward and shortened distances between individual stage layers – that's something I'd never heard before! It's attack seemed faster, but it was an illusion - the impact was clearer, but Chord presented the sound as a whole, which - paradoxically - allowed a longer, more relaxing listening sessions with sound being more natural, meaning with faster attack.

Upsampling

Upsampling as a technique used to improve the sound quality became popular in the late 1990s. After a while its popularity decreased because of improvements in players and DACs, with allowed to significantly reduce measurable jitter. Since then, most of the D/A chips featured upsampling algorithms and a circuits increasing bitrate. It seemed that the time of external upscalers had ended./p>

But listening to the results of Blu Mk 2 transport's upscaler one realizes, that it is not an obsolete solution at all. The transition from 88.2 kHz to 352.8 kHz using a single BNC cable and to 705.6 kHz with a double BNC introduced a major change to sound quality, and it was the latter that delivered the best results. The above text describes what I heard with 705.6 kHz signal.

The scaler used in this transport improves the resolution and deepens tonality. There is more information in the sound but it's darker and less distinct, ie they fit perfectly into “bigger picture” without attracting attention to themselves. Without upsampling, the sound was (in comparison) more compacted into a line. This is obviously an exaggeration, because one of the advantages of Chord is a huge sound stage, but only with the scaler I received something that was clearly better than the performance of my Ancient Audio player and at similar level as the best digital sources I know.

Transport

Although we are testing a set consisting of transport and DAC, I was curious about the class of the transport itself. I compared it with the transport section of my Ancient Audio player – after all they both share exactly the same as the Philips mechanism. The only variable was upsampling permanently enabled in Blu Mk II (88.2 kHz) and the DAC in the player. Differences proved to be significant. They were lesser than between performance with upsampling on and off, as well as between using one or two BNC cables, but still very clear.

The Blu Mk II delivers a darker, denser sound. Its tonal balance is set lower than with Ancient. There is also more information about tonality and dynamics. Ancient Audio on the other hand, was able to go deeper into the recording, to present contours of instruments in a more distinct way and place them closer to listener - Chord moves the foreground slightly away. But every time, coming back to Chord felt right, as if I was coming home - it was denser, more natural performance.

Summary

Of all the top CD and SACD players I've heard, the Chord system is the cheapest. Although the absolutely top-end devices are able to present even deeper tonality, even smoother sound and better differentiated sound layers, the differences are not very large. At a similar price level as Chord only the Audionet Planck with external power supply plays in equally engaging manner. But the English source gives you something extra, ie the feeling of being connected with natural music, with the dynamics known from analogue tapes. This is an outstanding source, a Compact Disc player, which shows that this format can offer an incredible value. A fully deserved, rarely granted GOLD Fingerprint.

The Chord Blu Mk II is a Compact Disc transport featuring an upsampler. Upsampling can be turned off but when on it might offer a few levels. When one uses it connected with DAC using a single BNC cable there are three options to choose from: 88.2 kHz, 176 kHz and 352.8 kHz. When connected to DAVE with two BNC digital interconnects, the signal can be upsampled to 705.6 kHz. The second switch can activate dithering. Dithering adds random low noise to the signal, which improves the performance of D/A converters with small signals.

Transport's chassis design is typical for the Choral series of this manufacturer, designed personally by the company's director, Mr. John Franks. It is a rigid shell made of two small milled aluminum elements - the device measures 333.5 x 98.5 x 142 mm and weighs 7 kg. It can either be placed horizontally, or at an angle, on a rack specially prepared for Blu and DAVE. On top there is a heavy, hand-locked lid, a small (too small) VTF display and several buttons. There are not too many of the latter which is good – the Mk I was really packed with them.

Outputs and inputs are located on the rear panel, There are two digital inputs – USB and BNC – signal from these is treated the same way as from a CD, ie it is scaled up before feeding it to DAC. As for digital outputs there are more of them:

• two AES/EBU, that can work separately (44.1kHz & 88.2 kHz), or in Dual AES mode (88.2 kHz & 176.4 kHz),
• BNC (88.2 kHz, 176 kHz and 352.8 kHz),
• two BNC sockets that my work independently (88.2 kHz, 176 kHz & 352.8 kHz) or in Dual BNC mode (176 kHz, 352.8 kHz & 705.6 kHz).

The device uses a modified Philips CD-Pro 2 LH (VAU1254/31 LF) drive. Inside I found SMPS and transformer isolated digital outputs. It's great engineering and make and finish are outstanding.