Berkeley Audio Design Alpha USB Interface

The USB Problem Is Finally Solved

Equipment report
USB interfaces, clocks, and soundcards
Berkeley Audio Alpha USB
Berkeley Audio Design Alpha USB Interface

Although the PC server sounds phenomenally great, the iMac/Alpha USB was better in virtually every sonic criterion and inferior in none. First was the sense of space and the naturalness of the staging. The iMac/Alpha USB had a slightly less forward perspective along with much greater soundstage depth. Although the front of the stage was a little set back, instruments in the back of the hall sounded much more distant. The sense of bloom around individual instrumental outlines was more realistic and palpable. The Alpha USB made the PC/Lynx sound slightly congested and homogenized by comparison.

Within this sense of expansive space, I could more easily hear fine recorded detail, particularly instruments toward the back of the hall. Switching over to the Alpha USB system was like sharpening the focus on a camera; very-low-level detail that had been just a bit indistinct or smeared snapped into vivid clarity. I thought I had heard the HRx recordings in their full glory with my PC server, but I was astonished to discover another level of resolution and clarity.

The treble through the Alpha USB was smoother and, paradoxically, slightly more prominent. The presentation wasn’t brighter, just more alive and vivid. The treble had greater texture and increased density of information, yet was more finely filigreed and delicate. The top octaves also had greater smoothness and ease, particularly on high-level, high-frequency transients such as the upper octaves of fff piano passages.

The sense of hearing more information was partially the result of the Alpha USB’s superior rendering of transient detail. Listen to a Latin percussion instrument such as the güiro; the Alpha USB better resolved the instrument’s dynamic envelope to create a greater impression of hearing the instrument itself rather than a re-creation of it. Percussion seemed to “pop” from the soundstage with greater life. Micro-transients were also noticeably superior; listen to brushes on cymbals, to triangles, and to tambourine. By better resolving this low-level transient detail, the Alpha USB made the presentation more lifelike and musically vivid. I could better hear the mechanisms by which the sounds were created, which is always a good sign.

Finally, the Alpha USB had a greater sense of ease on high-level peaks, particularly during dense and complex passages. The music got louder more gracefully, with smoother textures and less homogenization of images. The presentation remained more coherent during the loudest orchestral passages, contributing to the overall sense of ease and involvement I experienced.

Because the Alpha DAC was receiving the same bitstream from both music servers, the only difference was in the timing precision—jitter.

Some of these differences could be attributable to the different computer platforms, so I compared the sound of the Lynx card in my PC to the PC’s USB output through the Alpha USB. The Alpha USB sounded better overall, although the disparity was not as great as when comparing the PC/Lynx to the iMac/Alpha USB. The specific sonic characteristics were the same, but the magnitude of the difference was reduced, suggesting that the Macintosh platform has a sonic advantage over the PC. That difference might be erased by a PC running Windows 7 and a better WASAPI driver, but I was unable to hear that configuration. Even if a Windows 7 PC can sound as good as the Macintosh, the Apple platform is much more pleasant to use.

The Berkeley Audio Design Alpha USB is a breakthrough product that not only overcomes the limitations of the USB interface, but provides a state-of-the-art method of getting audio out of a computer. Moreover, the Alpha USB makes this reference-quality performance available to non-technical music lovers who have a Macintosh and a DAC.

Though the Alpha USB’s $1895 price is considerably more than that of other USB converters, the Alpha is a bargain when you consider that it provides a simple, foolproof path for creating a state-of-the-art music server. Moreover, the entire digital front end of the iMac, Alpha USB, Alpha DAC, Pure Music software, and Straightwire digital interconnects costs about $8300. That’s not chump change by any measure, but it’s eminently reasonable for a music server and a DAC that deliver this level of performance. I listened to this digital front end as a source for electronics and loudspeakers that together cost more than $400k, yet never felt that the digital source was the weak link in the chain. In fact, I had the opposite reaction: This source allowed me to hear these ultra-exotic electronics and loudspeakers at their best.

One day computer-based music systems will be simple to set up, foolproof, ubiquitous, and uncompromised in sound quality. The Berkeley Alpha USB represents a giant leap forward in realizing this goal.


Type: USB-to-S/PDIF converter
Input: High-speed USB 2.0, Type B jack
Output: Switch selectable— coaxial SPDIF on BNC, balanced AES on XLR
Supported sampling rates: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz
Supported word lengths: Up to 24 bit
Supported operating systems: Apple Macintosh and Microsoft Windows
Mains power: 100 or 120 or 240VAC, 50/60Hz, IEC power input connector
Power consumption: 3 Watts line, 1.5 Watts USB, designed for continuous operation
Dimensions: 10.5” x 2.5” x 5” (including feet)
Weight: 2.5 lbs.
Price: $1895

Berkeley Audio Design
(510) 277-0512

Associated Components
Sonus faber “The Sonus faber” loudspeaker, BAlabo BC-1 Mk-II preamplifier and BP-1 Mk-II amplifier, Constellation Altair preamplifier and Hercules power amplifiers, Berkeley Audio Design Alpha DAC, Meridian 808.3 and Meridian Sooloos system (Ethernet connected), dCS Puccini/UClock, custom fanless and driveless PC server with Lynx AES16 card; Basis Inspiration turntable with Basis Vector 4 tonearm, Air Tight PC-1 Supreme cartridge; Aesthetix Rhea Signature phonostage; Shunyata V-Ray V2, Triton, and Talos power conditioners, Audience aR6t power conditioners; Shunyata CX-series AC cords; Transparent XL Reference interconnects; Transparent XL Reference loudspeaker cables; Straightwire USB-Link USB cable; Shunyata Anaconda interconnects and cables; ASC 16" Full-Round Tube Traps