BAT REX 3 DAC
"Despite what some would have you believe, all DACs don't sound the same, and they certainly don't all deliver in musical terms as well as the REX DAC 3.
Simply, this unashamedly expensive converter gets you closer to the music without you even realising it's doing it. Just let it weave its magic, and you'll be too immersed in what's being played to give another thought to all the engineering making it possible"
by ANDREW EVERARD | JUNE 12, 2020
MADE IN THE USA
The BAT second-generation SuperPak is now standard
REX 3 now incorporates BAT’s second-generation SuperPak as standard. The SuperPak assembly features the largest energy storage ever offered by BAT in a preamp or source component. One must admire the SuperPak in BAT’s reference VK-655SE solid-state power amplifier to find a SuperPak assembly of comparable energy storage.
REX 3 DAC’s SuperPak dramatically adds to the dynamic performance of the component by extending the bass and offering greater midrange authority..
Zero negative feedback for supreme purity and six 6C19 vacuum tubes
REX 3’s analog output stage follows the Balanced Audio Technology purist approach of using zero negative feedback to achieve the desired goals of wide bandwidth and circuit linearity. No buffers or followers are used anywhere in the signal path.
REX 3 also features a high-current output stage with a total of six 6C19 vacuum tubes. One pair of 6C19 tubes serves as current sources for the power supply of the elegant, trademarked Unistage design.
Just as in BAT’s REX 3 preamplifier, REX 3 DAC also employs amorphous-core second-generation transformers for output coupling. No capacitors are utilized in the signal path. To celebrate its 25th anniversary, Balanced Audio Technology worked closely with its long-term industry partners to improve upon the already stellar performance of their output transformer.
In the past decade, switching from coupling capacitors to output transformers made the greatest improvement in the sonic performance of BAT preamplifiers and source components. In REX 3 these new second-generation BAT output transformers feature Cardas Audio's finest OFC wiring. According to BAT co-founder and chief engineer Victor Khomenko, "The new transformers' electrical performance sets a new benchmark in achieving low-restriction signal purity and linearity. This is heard as improvement in openness and transparency. They are the most ideal devices to maintain the benefit of our UniStage (single gain-stage signal amplification) architecture. There is less between the listener and the music."
Proprietary DAC module runs at an ultra-high clock rate, uses custom filters
With REX 3 DAC, BAT wanted to create the most compellingly natural reproduction of the musical source. Ringing from filters that provide a perceived albeit false excitement in playback have no place in REX 3’s design.
Instead, the proprietary DAC module runs at an ultra-high clock rate while employing custom filters to reconstruct the analog signal in a way that specifically complements REX 3 DAC’s unique high-current vacuum-tube output stage.
Designed by one of the founders of the SACD format, and all-round ambassador for DSD, Andreas Koch, his AKDesign AKDAC-3 filter and converter solution lies at the heart of the REX 3. Key to this DAC is its proprietary upsampling and adaptive digital filtering, the latter bearing a conceptual similarity to Denon’s ‘Advanced AL32 Processing’ (ALPHA or Automatic Low-Pass filter Harmonic Adjustment). Koch’s vision of the adaptive filter also has the transient integrity of the music signal at its core, choosing the optimal algorithm on a sample-by-sample basis.
Ultimately the data is upsampled to 11.3MHz, and the word-length truncated to a bitstream, before it is low-pass filtered to reveal the desired analogue (music) signal. Bottom line, and In this implementation, the REX 3 DAC handles PCM inputs up to 384kHz/24-bit and DSD512, at least via its USB input.
BAT REX 3 DAC SPECIFICATION
24-bit/384kHz PCM, 4x DSD (11.2896MHz)
24 bit PCM / DSD 512
USB, 2 x S / PDIF (RCA), 2 x Toslink (optical), AES / EBU (XLR)
Analog outputs / Output Impedance
1 pair balanced (XLR) / 1 Kohm
Tube Complement / Global Feedback
6 x 6C19 / Zero Feedback
Silver or Black
Dimensions (w / d / h)
19 x 15.5 x 5.75 inches
Price $ 20,000
by ANDREW EVERARD | JUNE 12, 2020
Right Off The Bat
Clearly the REX 3 DAC is a long way from the fallacious stereotype of 'well, all DACs are not much more than a chip and a simple output stage, so why are they so expensive ?. There's a lot of engineering going on here – even if the remote looks like it's escaped from a 1980s TV – and fortunately no shortage of performance to set the REX 3 apart from its peers.
Fire it up and right from the off – well, right from the minute or so's wait while it soft starts and stabilises itself ready for action – you realise you're on to something special, even when doing something as simple as playing CD-quality music in through one of the coaxial digital inputs.
An album like Yazz Ahmed's Polyhymnia [Ropeadope RAD506CD] is immediately notable for the way the transients of Sophie Alloway's percussion opening 'Ruby Bridges' really zings out of the speakers, and then remains just as crisp, tight and focused however busy the track becomes, the slinking beat driving the music along.
And with more than 30 musicians involved in this album, things do tend to get a bit complex at times, yet the beauty of the REX 3 DAC's sound is that it gives every instrument, every line of the scoring, plenty of breathing space, allowing the listener that luxury of 'listening around' the performance, to focus on single performers or luxuriate in the sheer spread of sound.
It's an experience akin to that 'live performance' presentation so often sought, and a very long way from the technical fireworks with which so much audio equipment seeks to dazzle. Instead, when one reaches the album-closing homage to influential saxophonist Barbara Thompson, the lasting impression is of the rich variety of musical colours and textures on offer in the playing and recording, and not how good the hi-fi is sounding.
King Of Hearts
That sparkling sound, packed with freshness and vitality while maintaining the illusion of total ease, is the clever stuff here, as is clear with Compagnia di Punto's 'small band' recordings of Beethoven's first three Symphonies.
[Deutsche Harmonia Mundi 19439706502-2; 48kHz/24-bit]
With just 11 musicians deployed instead of the usual massed forces, these arrangements are sprightly, crisp and intimate, and the REX 3 DAC again does that wonderful thing of taking the listener to the heart of the music while allowing each individual contribution to be examined if required.
That's not to say it can't turn on the thunder if really necessary. With the blazing 'Walk On Hot Coals' from Rory Gallagher's Check Shirt Wizard live set [Cadet Concept/Chess 0836846; 96kHz/24-bit], the sheer vitality of performances, recorded in 1977 on the Rolling Stones and Jethro Tull's Maison Rouge mobiles, is irresistible.
Mixed from the original multitracks, the album allows the guitarist's performances new life, and the REX 3 DAC's winning combination of spark, speed and dynamic power makes the most of them, whether Gallagher is blues picking almost solo, or crashing it out with the band.
With all this ability, it's a given this remarkable DAC will do its thing with demo-quality jazz, too, and it passes the piano, bass and brushed drums test with total nonchalance. But don't even consider it if you limit your musical choices by what's likely to show off your system at its best. So well does the REX 3 perform across the board that you're going to be spending a lot on music.
by J LOH | JUNE 13, 2019
It has been almost 37 years since digital audio playback was introduced to the consumer market with the launch of the Compact Disc back in 1982. In its relatively brief history, we’ve seen the birth and death of multiple physical formats (goodbye miniDisc, Digital Compact Cassette – and debatably, the CD itself?) and the progression to high-resolution formats and streaming delivery systems.
The technology has evolved so much since then and likewise, the quality of playback – yet, there remain significant numbers of detractors to digital audio. The critique most heard is that digital is cold and sterile, lacking an ability to warm the heart and make a connection to the human soul the way analogue formats can.
Whether there is any merit to these claims is debatable – but anyone would be hard-pressed to say the same if they listen to the REX digital-to-analogue converter from Balanced Audio Technology.
Any product from the BAT stables with a REX label on it is not to be taken lightly. It signifies that this is the company’s top-of-the-line, no holds-barred product and represents the pinnacle of BAT’s engineering expertise. So, the REX DAC joins the REX preamp and mono-block power amps on the BAT throne. It is also interesting to note that there is no REX phono stage… yet!
What makes the REX DAC so worthy of the crown? For starters, it does all the usual digital formats up to 24-bit/384kHz PCM and 4x DSD (11.2896MHz). At the very heart of its digital-to-analogue conversion process is not any ordinary chip, but a field-programmable gate array (FPGA) from AK Design.
What does AK stand for, you ask? Well, those are the initials of Andreas Koch, the main man behind the design and creation of the DSD format. If you want the digital decoding done right, who else to go to but the one who came up with the concept in the first place? (Kind of like listening to a recording of Sergei Rachmaninov playing his own piano concertos, eh?)
It doesn’t stop there. The REX is a fully-balanced dual-mono design and employs two large toroidal transformers in its power supply, backed up by a bank of massive custom-made capacitors.
The other thing you’ll see is that it employs six 6C19 triode tubes. These are rated at six watts each, which would actually be enough to power some high-sensitivity speakers. Using them in a line-level stage means they will be working way below any maximum operating demands.
Finally, instead of using direct or capacitor coupling in the output stage, BAT has decided to use amorphous core output transformers instead. The exact electrical science of why this is superior is complicated, but let’s just say transformer coupling is what is used in legendary and highly-regarded mixing consoles – the Neve, for example (do a search and you’ll see recording and mixing engineers raving about its superior sonics).
All this hardware takes up some serious real estate – the massive 14.5 x 48 x 39cm (h/w/d) unit weighs in at 14.5kg.
Setting up the REX is a snap. As it is a fully-balanced design, there are no single-ended outputs available and you have to use locking XLR plugs. Those who do not have XLR connectors can still use it with XLR-to-RCA converters, as I did.
It has six digital inputs – one USB, two Toslink optical, two S/PDIF electrical RCA and a single AES/EBU XLR.
As expected with a complement of six tubes, the REX does run a bit hot, so ensure that it has sufficient ventilation; an air-conditioned room will also add to your personal comfort.
With all that in place, the only thing left to do is to let the music play and immerse yourself in the REX DAC’s marvellous sonics.
And simply glorious it is. It’s not about analysing in detail each and every aspect of its performance, it is the gestalt, the sum of its parts, the ability to draw you into the sonic landscape it paints that beguiles and keeps you listening hour after hour.
As a vinyl aficionado, my listening preference, admittedly, veers towards LP playback (fellow record lovers will understand what I mean). The physical aspect (i.e., the hands-on ritual when playing LPs) aside, there is nothing in the sound that makes me yearn for vinyl. The REX managed to imbue a warmth and a connection to the music that I have never ever experienced with digital playback.
Playing the same music on vinyl and high-resolution digital files was fundamentally different, of course, but provided valuable insights. LP playback tends to be harmonically rich, but the REX does deliver this in huge spades, Yes, it was of a different nature but it provided a similar musical feel – the sensation that you hare hearing more than just the notes the performer is relaying with his instrument or voice. Going out of the way somewhat here, but in some instances (the Doors and Led Zeppelin remasters, for example, where the source files are presumably the same) there was actually better low-end and treble extension as well as transients with the REX!
What really wowed me was listening to “inferior” CD-resolution 16-bit/44kHz playback. In every DAC I’ve used until the REX, there was always the feeling that there was “something missing” from the music, in addition to some graininess – particularly higher up the frequency range – that detracted me from complete immersion in the sound. This was almost completely negated when using the REX. Yes, there was a lower level of absolute resolution and the soundstage was a little flatter than with high-resolution files, but the resulting sonic retained the same musical allure and was never fatiguing. This gave new life to the entire library of rips from my CD collection!
Another outstanding aspect of the REX was how it painted a vast soundstage from everything I put through it – superior to anything I have heard in my system before. It wasn’t just about an increased breadth and solidity of the imaging, there was a tangibility to each individual instrument and voice within the mix that drove it home.
I attributed this to the REX’s ability to bring out the subtleties of the artistes’ performance – the rise in volume as bow pressure is increased across the strings or the crescendo in a the human voice as the singer goes through an emotive phrase. It was all so palpable that the overused phrase “sounds so real it was almost like a live performance in the room” applies here.
THE LAST WORD
Will the BAT REX DAC suit everyone’s taste then? I would say yes in a heartbeat. To be able to achieve such a high degree of analogue-like playback from any digital medium is truly something to be heard with your own ears.
The only possible situation where it may be “too much of a good thing” is when the rest of the system is already warm-sounding and employs tubes in multiple components along the chain – but then again, this may be exactly what the tube-loving crowd may actually want.
True, not everyone will be able to afford the REX DAC, but that’s the price one will have to pay for such a kingly performance.
by FALK VISARIUS | APRIL 19, 2019
BAT REX DAC - The Royal Pleasure
You approach a king with respect. This is also the case with the recently released BAT REX tube DAC by the American premium manufacturer Balanced Audio Technology, which was founded in 1994 by Victor Khomenko and Steve Bednarski. The approach was made knowing that the list price was also a royal 19,200 euros. That alone demands respect. Accordingly, my expectations of the noble digital-to-analog converter are high. At the same time, however, the anticipation of being able to test something so exclusive in your own four walls.
Given the price of this DAC, one can'y help thinking that If the questioner cannot accept the search for perfection, coupled with sufficient solvency, as a motive for owning a noble hi-fi device, it is of course difficult to contemplate acquiring such a device. The audiophile connoisseur, the seeker, may have to ask himself a completely different question after a REX DAC rendezvous - namely the counter-question : How easy is it for you to give the REX DAC - once heard - back? That's mean. Because the golden rule applies : do not hunt what you cannot kill. The “want to have” effect occurs quickly after a listening weekend and the pain of loss can be noticeable. But more about the sound later.
A small side note - and as regards the "royal" REX DAC. Watch aficionados will be able to understand the facts quickly :
This weekend, I saw a Rolex Daytona from the pre-series offered by a large online watch dealer for 19,200 euros, exactly the price of REX. This is a model from the previous Rolex series. Unworn. List price of the current Daytona series : 11,800 euros. Waiting time : years! Conclusion : The price level on the market is an incredible result of supply shortage.
But let us now we turn to the REX DAC ...
Balanced Audio Technology sees the REX DAC as a "precision instrument" with state-of-the-art technology that is used in both the digital and the analog section. On the digital side of the converter, the design by Andreas Koch is used and is characterized by an extraordinarily high clock frequency in order to enable the most gentle and imperceptible filtering possible in the output. The filtering takes place according to BAT specifications (custom design).
The primary goal is to minimize or eliminate the "pre-ringing" of the filters and thus to switch off unwanted stimuli from the music signal. The filters of the digital part are matched to the tube characteristics of the analog stage. The converter accepts digital signals via TOSLINK (2x), Coaxial (2x Cinch), AES and USB.
The analog design comes from Victor Khomenko. A special feature here is a high-current vacuum tube stage, which at first you would not even expect to find in a digital / analog converter. The common misconception is that a D / A converter is a digital device - i.e. a purely digital device. The fact is, however, that in addition to the high-quality digital conversion, the subsequent treatment of the analog signal has an immense influence on the sound. Finally, the signal has to be processed as in a preliminary stage and transported to the outputs for transmission. In the case of the REX DAC, the outputs are exclusively symmetrical (XLR), which enables consistent signal routing in the device.
Six 6C19 tubes are used in the high-current vacuum tube stage. A pair of the 6C19 tubes serves as a power supply for the elegant and for patented BAT Unistage (TM) design in the analog part. The analog stage of the REX DAC works completely free of negative feedback (Zero Negative Feedback) in order to be able to use the greatest possible bandwidth and circuit linearity. In addition, neither buffers, nor follower stages are used in the signal path. The signal path is also free of capacitors.
Another technical delicacy : Just like in the BAT REX II preamplifier, an amorphous core transformer in the REX DAC handles the output coupling. The whole thing combined with massive power supplies, reinforced by two toroidal transformers and a transformer-coupled output stage. BAT wants to bring the analog part of the DAC to a level above many reference tube preamps. The combination of the effort on the digital as well as the analog side of the signal should get the best out of digital recordings.
At the blue-blooded guest performance, the two of us are honored. To be able to listen appropriately and to exchange what we have experienced. The place of the event was my listening room, in which the REX DAC played directly on the GENELEC 8260. Neatly wired with balanced XLR. The streaming bridge Lumin U1 was an adequate player. The music was provided by my Synology NAS and the LUMIN L1 server.
The session starts with Ellie Goulding. I like this artist, because the album “Halcyon” doesn't make any audiophile claims. The track "Dead In The Water" is rendered in an "atmospheric way". In some system chains this track sounds "irrelevant, and almost trivial".
This is Quite a different matter here with the REX. Ellie Goulding is clearly outlined in the middle of the speakers. The deep bass creates a wonderful backdrop when the voice forms in the head of the then 26-year-old American. Despite reverberation and trickery during the recording ... "Oh yeah, I'm de-ad in the water - still lo-oking for ya ... Can't you see ... "Goosebumps" ... We'll listen to it again just to be on the safe side.
A good tip, if you are at the upper end of the hi-fi performance scale, listen to where you least expect the surprise. In this case with the AC / DC heavy current electricians. "Hells Bells" from the "Back in Black" album. Recorded in 1980. The super authentic bell knocks me out at the beginning. I can practically hear the metallic structure of the bronze body. How the natural frequency moves through the bell wall. Like a visit to the belfry of a church. The REX DAC works the metallic hissing of the hi-hats with "Shoot to thrill" out of the sound. And AC / DC really doesn’t bother to give way to individual instruments in their mighty thrust forwards.
The Rolling Stone Charlie Watts, who pays tribute to the drummer “Art Blakey” in the “Charlie Watts and Jim Keltner Project”, also provides a boost. The recording has size, volume..it is "excessive". The REX DAC, however, maintains a complete overview ... presents fine details in the greatest chaos. The listener can zoom into the soundscape at will. Despite the opulence, the sound remains natural. Everything remains well positioned.
Now for a "hard" change of pace : Modest Mussorgsky's tracks on “Pictures at an Exhibition” are intended to create a contrast. The exceptional pianist Evgeny Kissin now takes a seat at the grand piano :
In the "Ballet Of The Unhatched Chicks" every single attack can be followed in this fast-paced piece ... each as a natural sound event in itself. The grand piano can be perceived as a natural instrument, the attack of the string, the resonance of the frame and the wooden body in huge passages, for example in "The great Gate of Kiev". I've never heard a piano in such detail, and as realistically as with the REX DAC. The great gate of Kiev describes the orchestra accentuated in a self-contained, well-sorted room filled with mood, tension, dignity.
Another change : This time to John Watts, Fisher Z's mastermind. On his 2007 album "It Has To Be" Watts describes various life stories that he has collected. In Inga's post-war story during the economic boom, “Hard work and Happiness”, the song comes in bold, guitar struck hard, distinctive voice. The S-accent was realistic, but not annoying. "Inga, can you tell me what's the secret of your happy mind? … Hard work, and happiness… “I want to sing along loudly.
To be on the safe side, we'll listen next to one of our standards : "Poem of the Chinese Drums". The bass is powerful and contoured. The skin of the drums seems to fade away forever. The REX DAC draws a perfect arc of suspense. The big drum kicks in ... very deep ... all black. The king celebrates the crown of precision: naturalness.
While listening, the listener experiences something special. He not only hears what is happening, everything suddenly makes sense, the sound events lock into place. Rhythm and timing. Suppleness but still with bite.
To have the king self-proclaimed in your name is one thing. To be allowed to wear a crown with your head held high is another. Balanced Audio Technology has truly earned this privilege with the exclusive BAT REX DAC. With the right player, the rhythm and timing are right, the music gets into a river that does not adequately describe the technical word precision. Rather, the listener experiences music in an unbelievable naturalness and corporeality.
The BAT REX DAC confidently embodies what its name promises : A true audiophile king among digital / analog converters.