BURL Audio: B2 Bomber ADC & DAC

Here’s another game-changing product that deserved multiple opinions. Allen Farmelo, who also collected opinions from several other well-known engineers, leads with his review, and F. Reid Shippen follows with his opinion. (Each $2500 street; www.burlaudio.com) –AH

The notion that a piece of audio gear can achieve complete sonic transparency is a bit idealized, yet when it comes to converters we hear a lot about neutrality, accuracy and transparency. It’s true that many designers have stabilized digital components and minimized the amount of color imparted by analog signal paths to produce converters that are, relatively speaking, quite transparent. This near-neutrality is especially desirable in the digital-to-analog converters we rely on for accurate monitoring.

When we flip the equation, however, and consider analog-to-digital input, transparency isn’t always so desirable. From day one of digital recording to the present, there has been a collective lament over the loss of the sonic coloration that analog tape machines brought to recordings. Further, the coveted preamps, EQs and compressors of the “analog era” were designed specifically to work with the sonic imprint of analog tape machines. As digital converters took over for analog tape decks, it was as if the final coats of varnish had been stripped away from our recordings.

Making ADCs as transparent as possible is perhaps one of the biggest oversights of the past 20 years of pro audio gear design. Only a few designers have aggressively addressed this issue. Dave Hill of Crane Song put out his brilliant HEDD 192 (Tape Op #26) that allows you to dial in varying amounts of second and third–order harmonics to an otherwise very neutral, high-quality ADC and DAC. Universal Audio put out their excellent Class-A 2192 (#39), which created “harmonic glue” with op-amps that sound “like tubes” so that their device was like a “musical instrument” (quotes from their promotional video). Not insignificantly, Burl founder Rich Williams designed the UA 2192, laying down a strong foundation in his understanding of how to integrate Class-A analog circuitry with top-notch conversion. The HEDD and the UA 2192 are the only converters I’ve ever heard anyone really claim to love. These were huge steps forward, but these two designs put both ADCs and DACs in the same box. They hadn’t quite taken the disparate goals of the two realms of conversion to the logical conclusion — design two very different converters. That’s exactly what Burl Audio has done with their B2 Bomber DAC and ADC.

With the B2 DAC, you get nearly transparent, yet very musical, conversion that is ideal for monitoring; and with the B2 ADC, you get the lush color and mojo of Class-A, transformer-based analog circuitry with a sound that is very reminiscent of analog tape decks. While these two converters meet very different goals, they function as a killer combination that makes recording to digital a musically satisfying analog trip and monitoring back to analog a listening experience you can trust and enjoy. These are the most exciting converters to hit the market in years, taking us into a new era in which digital recording may just have finally caught up with its analog ancestors.

The inside of the B2 ADC is packed with Class-A circuits and a pair of custom Burl BX1 input transformers. On the faceplate are the typical switches you’d expect for selecting sampling frequency and so forth, but one unique front-panel control is an input attenuator, a key feature of the design intended to let you instantly change input headroom in order to hit the front end hotter or cooler, depending on how you want the converter to sound — just like any piece of analog gear.

I’ve used the Burl B2 ADC in all kinds of situations, and I’m completely floored by how good this thing sounds. One of the most stunning applications was running mixes off my Studer A80 1/2’’ 2-track through the B2 into Pro Tools at 96 kHz as final digital prints. Here I was comparing the B2 to my Crane Song HEDD, which I’ve relied on to convert analog mixes to digital for many years. I love my HEDD, but I have to admit that the Burl really had it up against the ropes. What blew my mind was how easy it was to listen to mixes converted by the B2. Things just chilled out in a really great way, but with no loss of detail. Cymbals were particularly smooth yet shimmery, and the whole stereo image was wider and a bit deeper than with the Crane Song. It’s important to note that the center of the mix with the Burl was very focused, too, with a tight, punchy low end that brought out the best my Studer had to offer. To improve width and focus is no small feat for any piece of audio gear. In the end, comparing the HEDD and the Burl was like comparing a Ferrari and a Lamborghini — which version of completely awesome high-end performance do you prefer? It is absolutely a matter of taste at this level.

Tim Hatfield and Eric “Roscoe” Ambel (issues 67 and 13) turned me on to the A80/Burl combo at their Coyote Technical Services Recording Rig in Brooklyn. Both of them rave about it. Tim put it this way, “I love what it does to my mixes. I usually go to tape first then play it back into the computer through the B2. When I do, the top opens up, the bottom gets tighter, and vocals seem more present. What else do you want? I bet Elvis would have used it.” Roscoe says, “After six months with this box, the simplest way I can describe the B2 is that it is a great piece of audio gear as opposed to another piece of computer gear. Emphasis on audio. It’s a real game changing box for tracking and mixing.”

As an audio tool, you can shape the sound to taste by pushing a little harder or easing off. Want a fatter snare sound? Push the front end of the B2 ADC and it rounds off the transients and adds a nice little extra punch as the transformers do their thing. Want a more dynamic and clear snare? Open up the headroom on the B2, back off on the preamp a bit, and the transients are all intact. With the Burl, “hitting the converter” in order to achieve a desired sound isn’t breaking the rules; it’s encouraged by design.

At this point, it’s easy to imagine that I’ve simply gone off my rocker for Burl, caught up in a wave of enthusiasm, so check out what others in the field have to say. Mastering guru Greg Calbi says, “The Burl B2 Bomber ADC has extremely clear and detailed low end without sacrificing clarity in the mids or highs. Above and beyond that, with the Burl I hear expanded front-to-back imaging — something I try so hard to achieve in all of my mastering work. The Burl is the perfect antidote for mixes which have been caught ‘in-the-box’ needing more clarity and warmth.” And Tape Op contributor Joel Hamilton says, “The Burl B2 ADC made me excited about digital again. I mean that. No single piece of gear meant to interface directly with my Pro Tools HD rig has made me get excited — ever. You know the feeling — you unpack the Chandler thingy, or the Sta-Level, or the EQP-1R, or the Symetrix 501, and you can’t wait to use it on the mix you are working on right now. While producing/engineering something for Matisyahu and Dub Trio, I could hear the Burl doing something so great; it’s my mix, but wider and more 3D. There was a ton of low end happening as it was a Dub/Reggae thing, and the Burl tightened it up a bit while losing none of the physicality I had going on. I am ready for the multichannel version of this. Really. I need at least 16 inputs of Burl.”

Okay, time to start thinking in the opposite direction and take a look at the B2 Bomber DAC, the digital-to-analog complement to the B2 ADC. One of the things I immediately like about Burl as a company is that they openly embrace the fact that every DAC is going to have its own sound due to differences in component choice and design, no matter the attempts at minimizing sonic coloration. Therefore, if there’s no such thing as absolute purity in sound, why not make the DAC sound like something good, even as it strives to be pure? With the B2 DAC, Burl uses no transformers and no capacitors in a fully discrete, Class-A design loaded with their proprietary BOPA1 op-amps. The lack of capacitors and transformers minimizes the amount of color imparted by the analog signal path, while the op-amps offer up the “sweet tone” of the unit. It’s as if Burl has said, “Okay, we’re not going to load it up with analog mojo because it should be relatively transparent (bye bye transformers and caps), but if it has to sound a certain way, it might as well sound good (hello op-amp).” Did Burl succeed in its goal to simultaneously deliver accuracy and musicality? I asked two mastering engineers to spend time with the B2 DAC and got some of their impressions down in writing.

Jessica Thompson is the mastering engineer at The Magic Shop in NYC. She specializes in archival restoration, currently working her way through the Newport Folk and Jazz Festival archives, and she does plenty of modern mastering there, too. “With the Mytek 8X192 paired with my ATC monitors and good room design, I always feel confident that what I’m hearing is unadorned. There’s no extra punch or sparkle —just straightforward, clean lines. Since I do a lot of audio restoration on historic recordings, I rely on the accuracy of my Mytek DAC and monitors to hear extreme details — tiny dropouts or a lick of distortion on a vocal. Compared to the Mytek, the Burl seems a little sweeter, less plain, but not necessarily less accurate. The upper-mids ring like crystal without any of the fuzziness I associate with lesser quality converters. The Mytek also has a lovely high end, but the Burl’s is especially clean and pretty. The highs zinged without sizzling, which I can imagine being beneficial during long days of mastering or mixing because there will be less ear fatigue. Via the Burl, the midrange pops forward with more dimension than via the Mytek, especially on mono recordings. Because they’re both excellent converters, it’s hard to determine whether the Burl is hyped or the Mytek is particularly flat in the mids. Mainly, it seemed like there was much more depth in the center and mids with the Burl, and that dimensional aspect gave the music a very lifelike feel, which is lovely for listening and helpful when trying to separate out instruments in a muddy or tight mono recording. On the other hand, the mids also led me to consider whether working off the Burl would make me ease up on pushing vocals or other center/mid info forward when needed.”

Next the B2 DAC travelled uptown to the mastering room of Howie Weinberg at Masterdisc to spend time with Matthew Agoglia. Matt ran the Burl through its paces against their DCS DAC, which they clock off of an Antelope Audio 10M (Tape Op #68). Keep in mind that the DCS cost about $10,000 fifteen years ago and has been a standard in mastering studios for well over a decade. On top of that, the Antelope system runs close to $8000. “Overall, the Burl (whether clocked to the 10M or internally) has a more neutral, smooth and transparent character compared to our DCS. The DCS has a color in its midrange, a tightness in the bass, and a subtle crispness in the highs. We could say that the DCS is more curvy, sounding different in different areas of the frequency spectrum, while the Burl is very smooth and linear, sounding very similar throughout the frequency spectrum. In particular, the Burl’s low end was actually a bit more extended, with sub frequencies a bit clearer, while the DCS had a very pleasant low end focused around 80–120 Hz. The Burl also sounds a bit wider than the DCS. When clocking the DCS off the Antelope 10M, we get that larger-than-life sound that some describe as “hype” — not necessarily a bad thing in mastering because you don’t end up adding too much EQ or other processing to achieve your results. I wondered if I might be inclined to EQ/process more with the Burl handling my DAC duties because I’d want to hear more excitement. Note that when I clocked the Burl to the 10M, it definitely took on more of the excitement I heard with the DCS, bringing the two converters closer in sound. Please keep in mind that we are talking subtle differences here. The Burl at $2500 is a bargain!”

In my own critical listening at The Farm (my mixing room in Brooklyn), I compared the B2 DAC up against my HEDD, and I found them so similar that I can’t honestly say that the differences I heard are terribly significant. Both converters are crystal clear, and there is no difference in the amount of information I was hearing. In terms of listening pleasure, the Crane Song excels at delivering a strong, focused center image, so for mixes where the interest lies in the center, I liked the HEDD a little bit more. Conversely, the Burl presents a wider and somewhat smoother image, so for mixes where there are a lot of interesting things happening on the sides, the Burl was a little more enjoyable.

I’m pretty thrilled about Burl for its own sake, but also because I think these converters are going to seriously raise the bar for other manufacturers of digital recording gear. If we’re lucky, Burl has chimed in a new era of digital recording where we no longer merely tolerate our recording devices but actually revel in their sound.

–Allen Farmelo, www.farmelo.com

Several years ago, I had the pleasure of totally geeking out with a handful of friends in the studio over choosing a new A/D converter. Naturally, we went overkill on it, and by the time we were done, we had tested just about every ADC available. There were a few standouts and a few surprises, and we learned a lot. My favorite, which I now own, was the Lavry ad122mk3. The runner-ups were the Weiss AD2, the Crane Song HEDD, and the UA 2192.

Off the top, the B2 ADC is a great sounding converter. Its unique transformer-input design makes it a challenge to test

I found the B2 ADC to be one of the best sounding converters I’ve ever heard. It rivaled my Lavry (which is high praise), especially on spacious and open tracks. Actually, it beat the Lavry on some stuff. The Burl has an incredibly wide soundstage, really nice depth, and detail for days. But, as the levels are cranked up and arrangements got dense, the Lavry’s stellar midrange and wonderful high and low–end extension won out as the Burl transformers went to work and started to saturate and ring. I found that I had to constantly mess with the input level to optimize the way I was hitting the B2 in order to achieve the sound I wanted. This is, depending on your point of view, either a really awesome and flexible tonal tool or a complete pain in the ass. Or both. Personally, I’m kinda in love with the sound — it’s worth the extra effort. Running in its sweet spot, it sounds great, and I expect that it will likely kick the ass of all but the best ADCs out there — at least until you enter the rarefied air of “different, not better.”

By the way, I cheated and sent a few mixes to some famous mastering engineers, labeled blind. Their comments were, “Detailed and spacious. Kind of audiophile (in a good way). Loud — nice and clean loud. Good sub, vocal presence, and soundstage.” Email me if you want to know who they are.

The sibling B2 DAC sounds great too — very full and thick. Next to my Dangerous DAC and my Lavry DA10, I would characterize its sound as “warm” or even “analog” — round and present in the mids, with a really nice, wide stereo image. The all Class-A, discrete op-amp design was based around a new set of passive filters, chosen for their extremely flat phase response — and no capacitors (for great bass). Supposedly, this allows the Burl to overcome some of the inherent limitations of older designs that could sometimes yield a flat or thin sound by rolling off the bass and/or making the top end edgy. The intent was to aim for the reproduction ability of great analog tape, and I think Burl nailed it. But neutral it ain’t, and that’s where I came into conflict with it. I mix through my conversion chain (as I would hope everyone does), and I don’t want my DAC adding additional coloration. If I were mixing through the B2, I feel like I would compensate in such a way that everything would come out with less bass, a bit carved in the mids, and too bright. Maybe the B2 sounds too good, or it’s possible that I’m just way too familiar with my current chain.

–F. Reid Shippen <reid.shippen@gmail.com>