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December 2009 / January 2010
Superior Audio Equipment Review

World Premiere
Acousticbuoy DAC2488 V3 Digital To Analog Converter
Go hear for yourself how great this component it is.
Review By Tom Lyle

Click here to e-mail reviewer.

 

Acousticbuoy DAC2488 V3 Digital To Analog Converter Unit  You might not be in the mood to hear me reminisce about my early experiences with digital audio, so I'll try not to be too long-winded: In 1987 or ‘88 I was given a CD player as a gift. This player was manufactured not by an audio company, but by a firm that was better known at the time for making photo copiers and printers. Which sort of makes sense because even though I was told by some that CDs would amaze me by their superlative clarity and tremendous fidelity, to my ears it this player sounded more like a major appliance than an audio product. I subsequently auditioned a few more players, but it wasn't until two years later when I ended up buying a Rotel RCD-855 that I thought I could listen to CDs with any serious intent, yet that was only because it wasn't relentlessly annoying. But after time passed I took someone's advice and obtained a Meridian transport/DAC, and discovered that this combo was unequivocally better than everything I heard before, and that digital might be worth taking seriously (that is, as long as I didn't directly compare it to the analog rig).

It goes without saying that even if one only considers playback of the lowly CD, over the past twenty or so years audiophiles have witnessed colossal improvements in the sound that reaches one's speakers, and even I'd agree that in many cases it's more a matter of preference than anything else whether one listens to digital rather than analog. Fast-forward to the present, where I've lost count how many CD players and DACs have passed through my system. I thought we've hit a brick wall, because these days, where it seems as if new techniques of conversion are released on a daily basis the language to describe a 44.1/16 CD played back on two different DACs that cost less than $10,000 always leans toward the nuanced: an increase in the perceived air or soundstage depth, a small but significant increase in the lack of grain, etc. When I first connected the Acousticbuoy 2488 V3 I had a flashback – here was a DAC that made a quantitative improvement in sound that was equal or better than the difference I heard between my lowly single-box sub-$1000 player and the Meridian combo – yet now the bar was set light-years higher.

 

Positively
Acousticbuoy DAC2488 V3 Digital To Analog ConverterAcousticbuoy is a small company located about 20 miles outside of Toronto , Canada . I positively reviewed their only other product, the Scorpio line-stage tube preamplifier in the June/July 2009 issue. The technical information regarding the Scorpio that Audiobuoy supplied was a bit limited, but not so with the DAC2488 V3. In the "Design Vision" section of the 2488's (I'll call the Acousticbuoy DAC2488 V3 the 2488 from this point forward) manual, Acousticbuoy argues that even though there quite a few methods in which to listen to digital audio these days, the CD is still "by far" the most popular. Of course they aren't so shortsighted that they'd be willing to limit themselves to this format, so the 2488 is able to decode not only a 44/16 digital signal, which it upsamples to a whopping 352.8 kHz, but it also accepts 48 kHz signals and upsamples them to 384 kHz, 96 kHz samples to 384 kHz, and 192 kHz to 384 kHz. Acousticbuoy set their sights high with the 2488, saying that they intended to forgo the design goals of maximizing profits by means such as reducing printed circuit board (PCB) layers and using less than perfect internal components, and instead design the 2488 from the ground up. 

The first thing they set out to do with the 2488 was eliminate the interference that comes from signal sampling. In Acousticbuoy's view, not only are there are images of the original signal that are multiples of each sampling frequency, but also radio frequency (RF) signals that are abundant these days also generate images that contribute to the degradation of the performance of both digital and analog systems, especially their signal-to-noise ratio. And even if these sampling images are located in the "inaudible" ultrasonic range, first-rate sound quality will not be possible as long as these unwanted frequencies exist. They also wanted to minimize the need for data correction, because they feel that "corrected" data is not necessarily equally to the original data. There are methods to remove unwanted image signals by filtering the input signal with a digital filter, and by using a simple analog filter at the DAC output. In the distant past, "brick-wall filters" were used, and then were replaced by digital over-sampling filters. In the 2488 1:1 digital interface transceiver with PLL advance jitter attenuation is used to filter the undesirable images and noise in the digital domain before the digital signal is fed to the DAC for conversion. The analog filter is a simple third-order design with minimal phase shift that Acousticbuoy insists does not degrade sound quality. 

Besides signal image and RF interference, a widely held belief is that a major cause of signal degradation is jitter, and the 2488 is designed to eliminate jitter associated with the clock signal of the system. The 2488 goes about its business of reducing jitter by using a very accurate oscillator they call the TCXO (Temperature Compensated Crystal Oscillator) which ensures that any resulting jitter's impact is negligible. They also use the most recent Wolfson WM8805 receiver chip as an active jitter attenuator to insignificant levels. But Acousticbuoy says that reducing jitter is hardly enough, so to improve its performance the 2488 uses very high quality op-amps that have very low total harmonic distortion (THD) and the power supplies are carefully chosen to increase system performance. The 2488 uses Mallory-Jamicon axial capacitors, a LM317T/LM337T regulator, Sanyo 125C audio capacitor, and Dale/Vishay resistors that are accurate to 0.1% in each channel.

The 2488 uses two circuit boards to separate the digital and analog signal processing, which minimizes cross-interference. To further reduce interference from digital-to-digital transformation, digital-to-analog conversion, and out-and-out audio playback, four-layer PCBs are used throughout the unit. The digital transformer is also isolated from the analog section to further reduce electro-magnetic interference. Acousticbuoy pays extra attention to interference that might arise from grounding problems as well, so their DAC is designed with the intension of separating all low-level analog grounds from the digital signal grounds. They are terminated at a single designated point on the system's ground conductor, so this way the ground potential of each circuit is just a function of its own ground current and impedance.

Acousticbuoy DAC2488 V3 Digital To Analog ConverterAs with their Scorpio preamplifier, the 2488 has a "hermetically sealed" 6mm (0.25-inch) thick aluminum case (with an additional 2mm on the front panel) to further reduce interference introduced by RF or electromagnetic fields. Although somewhat larger, the cabinet of the 2488 looks quite similar the impressive looking Acousticbuoy Scorpio preamp, with the same "titanium"-colored case which is very tastefully designed without any silk-screening or decals, but instead has characters engraved into the metal. A single blue LED on the right side of the front panel indicates that the unit is powered, and another single blue LED labeled "lock" on the left indicates that the unit is actively decoding a digital signal. The rear panel features both balanced XLR and unbalanced RCA stereo analog outputs, and S/PDIF coax (RCA) and AES/EBU balanced XLR digital inputs.

 

Extraordinary
For the bulk of the review I used very modest transports, although it would have been nice to hear the 2488 with a state-of-the-art disc spinner, the results from the unassuming units were extraordinary, to say the least. The differences between bargain priced Oppo DV-980H universal player and the approximately nine times more expensive (but still "affordable" by audiophile standards) Arcam DiVa CD192 CD player were negligible when listening to Red Book 16-bit/44.1 kHz CDs. Both were connected to the 2488 via a Virtual Dynamics or MIT digital cable. Of course the Arcam could only play standard CDs, whereas the Oppo was also able to feed the Acousticbuoy with 24-bit/96kHz audio signals from DVDs. I also had some 24/96 files on my computer downloaded from HDTracks that were sent to the USB output of the computer converted to the Acousticbuoy's S/PDIF input via an M-Audio USB Transit which converted the USB signal to the S/PDIF digital input of the 2488. But I spent the majority of my time listening to CDs. Of course the 24/96 files and DVDs had better sound quality, but that wasn't the point, at least if one believes Acousticbuoy and their assertion that the 2488 was designed for my CD collection, which outnumbers high-resolution discs and files by at least 1000:1 in my listening room's collection.

OK, so we all know (don't we?) that most, if not all, of the "important" musical information occurs in the midrange, and thankfully the 2488 did a swell job of reproducing not only an accurate picture of what is going on in that region, but thankfully did it in a way that can best be described as "musical". But by this time as it is so late in the digital game one should expect a player or DAC to reproduce Red Book CDs by being more than just "not-annoying". Thankfully the 2488 went far beyond this and was also quite adept at reproducing all frequencies with comparable skill, and sounded practically easygoing whilst doing so. Nevertheless, I suppose that what first drew my attention to the 2488's sound was its astounding bass response. Now, one should be fully aware that more bass doesn't equal better bass. But in this case the low-end was not larger-than-life, but very appropriate to each recording it was reproducing and at the same time creating a solid foundation for the rest of the sonic picture that appeared above these lowest frequencies. And the fact that it is the first thing I noticed does not mean that it overwhelmed the rest of the sound, it just was so much better than what I was used to hearing in my system.

The speakers were the Sound Lab DynaStat electrostatic hybrids which use one ten -inch woofer per side and are rated down to very respectable 27 Hz, but the Velodyne HGS-15b that augments them with its 15-inch woofer is rated down to 18 Hz. There was no question that even though there was very little information at those lowest waveforms the resonant frequencies were markedly discernable, not only by being felt in the gut, but also let their presence known by the tremors that shook the window frames. The room is treated with Echobusters panels so the quality of the bass is controlled to the point where one notices very few standing waves, and surely aided in delivering the high quality of the bass reproduced by the 2488. The deep bass was extremely pitch stable with extraordinary control, and as implied before, was very powerful.

The Acousticbuoy DAC2488 V3 was endowed with a realistic sounding midrange with excellent separation of instruments, and it was able to decode even the most complex recordings without ever sounding etched. In the upper midrange and into the lower treble there wasn't a hint of exaggerated transients or harshness to be found. I rather not say that the 2488 sounded analog-like, because it really didn't, so it would be safer to say that it sounded "super-digital", that is, it had the ability to decode intricate material to the point to where one can hear things deep into the recording that not only analog might miss, but inferior digital decoders as well. And it had the ability to render one speechless with its crushing bass response.  At the same time there was a musicality to its sound, and this was a winning combination in it added to the perception that one could hear everything that not only that the producers and engineers of a recording intended, but especially the musicians on the CD. When I spun the Naxos disc of Ralph Vaughn Williams 4th Symphony with the Bournemouth Symphony Orchestra conducted by Paul Daniels, the ventilation system of the Concert Hall in Poole , as I was expecting, was pretty easy to hear during the split second before the blast of the orchestra begins the piece. This is noticeable even with the most basic of CD players, but the 2488 made the sound integral to the environs of the recording. Not only that, but also convincing was the collective breath that the orchestra (and probably the conductor) took before hurling themselves into the dense score.

The brass, strings, and tympani begin their chromatic theme with overwhelming force, and as things quieted down the 2488 displayed that it wasn't only adept at conveying the Sturm und Drang of the piece but delicacy as well – the symphony abruptly changes from ppp to fff and back again numerous times in the first movement with the 2488 reproducing the micro- and macro-dynamic shifts with ease, as it was wearing a silk glove on its iron hand. Most Vaughn Williams symphonies are more often than not thought of as belonging to the Anglo–Pastoral variety, but definitely not the 4th, and at first one might hypothesize the reasons for this until one realizes that it might be because it was written during the tumultuous time period during the mid-1930s. But in the end that doesn't really matter because with this symphony he produced one of his best works – because of or despite of the political climate in Europe at the time. As the symphony unravels details such as the pizzicato bass fiddles at the end of the first movement and accompanying the winds and horns in the second movement are extremely believable sounding, and adds to the feeling that the 2488 is a top-notch DAC. But this sensation only arises when one can separate oneself from the utter immersion into the music that this piece of equipment is capable of. But the last note of the score calls for the whacking of the bass drum, and that certainly can rouse one back to reality with its sub-sonic thunder.

Those who have previously read some of my equipment reviews know very well that I tend to steer clear of most middle-of-the-road audiophile chestnuts used as musical illustrations. With apologies to their fans (and with such ubiquitous taste in music I should hardly be the one to judge), one's not likely to read about smooth-jazz or aging-female-cabaret-singers here. And although the somewhat off-beat rock I sometimes listen to might not test the range of a piece of equipment with the frequency range of say, a concert piece with triangle on the top and a 36-inch diameter bass drum on the bottom, I had the 2488 in my system long enough for it to be used listening to quite a bit of my old favorites and certainly long enough to get a handle on its sound. So, bear with me as I consider the extremely enjoyable time I had when playing a new UK re-mastering of Gong's You CD.

On this psychedelic jazzy-space-rock and witty improv-fusion from 1974 there are is an overabundance of acoustic and electric (and electronic) sounds, which include standard rock band bass/guitar/drums with male and female vocals, but also winds and brass, all sorts of percussion, and bubbling and swooping analog synthesizer. On the six minute "Master Builder", which is sort of akin to Bolero in that it builds tension through repetition, but instead of Ravel's brilliant theme Gong uses a sort of Buddhist chant introduced by a bass guitar line. The bass' low end heft mixed with the typical rock-recording rise in the mid-bass mixes with the kick drum to lay a solid foundation for the rest of the band which joins in on the riff. The ambience of the studio, located in an English cottage, can be heard even through the layers of reverb drenched "glissando" guitar (the clean electric-guitar's strings rubbed with a metal slide mixed with echo) and squiggling synthesizer effects that do their best to obscure it all. But more noticeable is the music, which includes a very natural sounding drum kit with explosive plate-reverb'ed snare and sizzling crashing cymbals, very gifted soprano sax improvisations, and trippy and ripping lead guitar. Not only did the 2488 do an excellent job of sorting out the overlapping sounds, but it communicated the meaning of the music within, that is, a great (and weird) rock ‘n' roll album from the third part of founder David Allen's "Radio Gnome" trilogy and its obligatory neo-hippy mythology.

The 2488 did an amazing job of performing the illusion of a solo instrument being projected into the listening room. The DVD-Audio of John Coltrane's Blue Train was perfect disc for this, and for some reason Lee Morgan's trumpet was the best at pulling this off, most likely because of the combination of the near perfect microphone distance realized by engineer Rudy Van Gelder and midrange purity thanks to Mr. Morgan. And of course the purity portion was the chief ingredient of the recipe, mostly due to his signature tone which was characteristically intense and at the same time beautiful. Curtis Fuller's trombone and Coltrane's tenor sounds were paragons of excellence, the color of their instruments spot on and the best I've ever heard them digitally reproduced (as apposed to hearing it on LP, but we won't go into that discussion/debate here).

 

Outperforms
The only weaknesses of the 2488 I can think of are a slight foreshortening of the depth of the soundstage along with a bit of forwardness. On most material even the five times less expensive Benchmark DAC1 PRE expands the soundstage behind the speakers more than the Acousticbuoy. In spite of this the Acousticbuoy outperforms it in just about every other area, and not by just a small amount. But I still think the Benchmark can hold its own judged against almost every other sub $10,000 I've heard (so far), except when compared directly to the Acousticbuoy. However, if one is concerned with features there are tons of DACs that have it all over the Acousticbuoy and that includes the Benchmark, which not only sounds great but has an internal analog preamp, analog input, two headphone outputs, and perhaps most significantly four digital S/PDIF (coax) inputs and a single USB digital input. But not everyone is looking for a multi-tasking DAC. So if one is primarily concerned with sound quality (and if you are reading this ‘zine, I assume you are) and realize that there is a simple fix for a missing USB input (such as the M-Audio USB Transit which has a street price of less than $100), these things shouldn't matter that much. I highly recommend an audition of the Acousticbuoy 2488 V3 so you can hear for yourself how great a component it is. And it is superb.

 

 

Specifications
Type: Digital to analog converter
Digital Inputs: S/PDIF 75 RCA, Balanced XLR, AT&T (Optional)
Input Word Length: 16 to 24-bit
Input Sample Rate: 32 kHz to 192 kHz
Conversion Word Length: 24-bit
Up-sampling: 44.18 to 352.8 kHz, 48 to 384 kHz, 96 to 384 kHz, 192 to 384 kHz
Analog Outputs: Single ended RCA: 2.5V RMS, Balanced XLR: 2.2V RMS.
Color: Silver or Titanium
Dimensions: 17 x 4 x 12 (WxHxD in inches)
Weight: 20 lbs. 
Price: $6000

 

Company Information
Acousticbuoy Products, Inc.
10 Northolt Cres.
Markham
Ontario L3R 6P5
Canada

E-mail: sales@acousticbuoy.ca
Website: www.acousticbuoy.ca

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     
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