Berkeley Audio Design Alpha DAC Reference Series 2 MQA

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Equipment report
Digital-to-analog converters
Berkeley Audio Alpha Reference DAC Series 2
Berkeley Audio Design Alpha DAC Reference Series 2 MQA

There’s another salubrious effect of reducing this distortion—a greater sense of ease. The treble no longer assaults; recordings with a forward midrange balance sound present and alive rather than shouty and aggressive; high-level transients don’t induce wincing; and the sound takes on a natural liquidity.

The third way in which MQA-encoded music reproduced by the Berkeley sounds more like separate instruments rather than a congealed monolith is the most obvious—greater dimensionality, spatial precision, air around instruments, bloom and life, rather than flatness and congestion. The new software opens up the soundstage in every dimension, particularly in the impression of air, space, and bloom around instrumental outlines.

Returning to “Glamour Profession,” despite having heard it countless times on countless systems, I experienced it in a new way. The horn section was better sounding in all the ways I’ve described: more organic, liquid, and clearly composed of individual brass and woodwind instruments; more richly detailed in timbre; and more spatially distinct from the other instruments. But it was the musical effect of these sonic differences that struck me. I could hear, with newfound clarity, how the synthesizer part and the horn arrangement worked together to form the song’s harmonic underpinning as well as its strangely hypnotic rhythmic flow. I heard for the first time how the horn arrangement weaved in and around the vocal line; it was as though I could hear the horn section and the vocal with equal clarity and equal contribution to the musical whole. Previously, the horn section tended to diminish in prominence when overlaid by the vocal.

I could have used any number of musical examples, but I chose this one because I’m so familiar with it, and because many of you are, as well. You can easily access the MQA version of this record and listen to it yourself and form your own conclusions. Gaucho is illustrative of understanding the specific sonic characteristics that made the Berkeley so compelling, but it’s not how I normally listen to music. The qualities I described were just as enjoyable on, say, Ben Webster’s Soulville, his expressive phrasing on “Time on My Hands” amplified by the bloom around his tenor revealed by the Berkeley. Or take Eric Clapton’s live album EC Was Here. The first track fades up to audience noise and Clapton’s opening guitar lick on “Have You Ever Loved a Woman,” and immediately I felt in the presence of a band on a stage, of being in an audience. With a Tidal account and an MQA DAC, there’s a wealth of great music in terrific sound to be enjoyed.

Surprisingly, many of the qualities I associate with MQA—greater timbral liquidity, reduction in glare and hardness, more realistic transient reproduction, finer resolution of micro-detail, greater space and dimensionality—were apparent with non-MQA sources after the MQA software upgrade. The improvement wasn’t heard to the same degree as it was with MQA files, but it was shocking how much better standard resolution and 96/24 files sounded than through the already superb Reference Series 2.

Obviously, if you own a Berkeley Alpha DAC Reference, the $595 cost of the software update is well worth it. If you are considering any DAC, regardless of technology or cost, you must audition the Berkeley Alpha DAC Reference Series 2 MQA. It’s not the most expensive DAC you can buy, nor the most feature-laden, but in my experience it is, by a wide margin, the best device extant for turning digital bits into a thrilling musical exploration.

Why No USB or Network Connection, and Only MQA Rendering?

Berkeley Audio Design’s products would obviously have wider appeal if those products included a USB input, a network connection, and MQA decoding rather than MQA rendering. The lack of these features places certain demands on the user; to use a USB source you must buy an external USB-to-SPDIF converter (and an accompanying AC cord and coaxial or AES/EBU digital cable) and find a place in your rack for another box. Without a network connection, you can’t stream music directly to the Berkeley DAC. Finally, because the Alpha DAC Reference MQA is an MQA renderer rather than an MQA decoder, you must have music-player software that performs the first MQA unfolding step.

Berkeley co-founder Michael Ritter explained the rationale behind these decisions. According to Ritter, Berkeley spent more than two years developing an oscillator with extremely low phase noise, and then finding a company that could manufacture such a precision device. Then it had to develop a real-world platform that would allow this oscillator to perform without degradation. This oscillator controls the timing of the conversion of digital samples to an analog output, the point where jitter (timing errors) matters. Berkeley’s custom oscillator reportedly has close to 20dB less phase noise than the current state of the art in commercially available digital audio oscillators. This translates to higher timing precision in the digital-to-analog conversion process, which reportedly has profound sonic and musical consequences. This oscillator is located a fraction of an inch from the DAC chip that it controls, connected with impedance-compensated lines using a special dielectric.

Every aspect of the Alpha DAC Reference Series 2 MQA’s design revolves around keeping noise out, and preventing this high-precision clock that Berkeley worked so hard to create from becoming degraded. For example, the chassis is full of RF shielding, along with extensive use of separately regulated power-supply stages that, unusually, employ shunt regulation. To keep noise from the DSP chip to a minimum, Michael “Pflash” Pflaumer wrote the software in assembly language, which is raw code with no “overhead” that would add noise-inducing processor cycles. Moreover, he wrote the code in such a way that the amount of DSP activity is fairly constant over time, rather than allowing bursts of high DSP activity. The idea is to maintain constant current draw by the DSP and prevent spikes of current that inject noise into the circuitry.

This heroic effort would be wasted if the Alpha DAC Reference were connected via USB to a computer or music server. The source device’s noisy ground would be connected to the Alpha DAC Reference Series 2 MQA ground, obviating much of the efforts at noise isolation and timing precision. The same is true for a network connection; computers are notoriously noisy. The solution for Berkeley was to build the Alpha USB, which takes in USB and outputs SPDIF or AES/EBU for connection to the DAC. The Alpha USB effectively isolates the DAC from the source component’s noise. Incidentally, I’ve tried the Alpha USB with many other brands of DACs, and it has always resulted in a significant sonic improvement over using the DAC’s integral USB input. In some cases, the Alpha USB has completely transformed the sound of a DAC, even a very expensive one.

When Berkeley researched MQA and decided to add MQA to its products, Berkeley planned from the start to build an outboard device that would perform the MQA Core unfolding step outside the DAC chassis. Although the Alpha DAC Reference Series had enough spare memory and processing power to incorporate full MQA decoding within the chassis, Berkeley wouldn’t compromise the Alpha DAC Reference Series’ performance by adding this computationally intensive step. Berkeley planned to build its own Core unfolding device because at the time, MQA insisted that all MQA-compatible DACs be full decoders that perform all unfolding and rendering steps in the DAC. But in January, 2017 MQA changed course and allowed the Core unfolding in music-player software. This obviated the need for Berkeley to build its own outboard Core unfolding device.

That left Berkeley with the job of implementing MQA rendering in the Alpha DAC Reference Series in a way that wouldn’t add noise and compromise the oscillator performance. All MQA licensees are given the rendering code by MQA in a computer language called C++, which the licensee incorporates into its product. Pflaumer, however, rewrote the MQA code in assembly language to reduce the number of processor cycles required. In the process of rewriting the code and incorporating MQA’s rendering software with its own code, Pflaumer went back to first principles and rewrote the entire software. He used the opportunity to take a fresh look at every aspect of the code and discovered ways to make the Alpha DAC Reference Series even better sounding. (Thus the reason for my Picasso quote that begins this review.) As you can read in the review, this new software for the Alpha DAC Reference Series not only adds MQA rendering, it realizes an astonishing improvement in the sound of conventional PCM sources.

It’s an ultra-tweaky approach that requires a bit more user involvement, but that’s what makes the high end the high end.