Berkeley Audio Design Alpha USB Series 2 USB Digital Audio Interface

The Berkeley Audio Design Alpha USB Series 2 is a high-performance USB-to-AES/EBU and USB-to-S/PDIF digital audio interface designed to isolate electrical noise from a music server or computer, reclock the digital audio signal and deliver it to an external DAC through a precision 110Ω AES/EBU XLR or 75Ω BNC S/PDIF connection. Berkeley Audio Design

Rather than operating as a simple USB converter, the Alpha USB Series 2 addresses three critical areas of digital playback: USB processing, electrical isolation and clock accuracy. It supports asynchronous USB Audio 2.0, PCM up to 24-bit/192kHz, individually tested low-phase-noise output master clocks and a dedicated isolated linear power supply for its digital output circuitry. Berkeley Audio Design

Asynchronous USB 2.0 High Speed Audio

The Alpha USB Series 2 uses a USB Type-B asynchronous USB Audio 2.0 input with Berkeley's proprietary high-speed, low-latency input software.

It is specifically optimized for modern streamer/server platforms with USB 2.0 High Speed Audio output rather than relying on a generic USB receiver implementation. Supported resolution extends from 44.1kHz through 192kHz at up to 24-bit. Berkeley Audio Design

Extensive Electrical Isolation

A major purpose of the Alpha USB Series 2 is preventing electrical noise generated by the source from reaching the DAC.

The USB receiver and processing circuitry are powered from the USB source, while the AES/EBU and S/PDIF master clocks and line drivers receive power from a separate isolated linear power supply. Berkeley specifies no DC connection between the USB input and digital output circuitry, along with a high degree of capacitive and inductive isolation. Berkeley Audio Design

This separation allows the USB-connected server and the precision digital-output stage to operate in electrically distinct environments.

Low-Phase-Noise Master Clocks

After receiving the USB audio stream, the Alpha USB Series 2 generates its AES/EBU or S/PDIF output using very-low-phase-noise, low-jitter audio master clocks.

Berkeley individually tests these clocks and identifies them as one of the three core technologies behind the interface, alongside its proprietary USB software and electrical isolation architecture. Berkeley Audio Design

The objective is to present the connected DAC with a clean, accurately timed digital signal rather than simply translating USB packets into another connector format.

110Ω AES/EBU & True 75Ω BNC S/PDIF

A front-panel switch selects between two digital outputs:

AES/EBU — 110Ω balanced XLR
S/PDIF — 75Ω coaxial BNC

Both support PCM up to 24-bit/192kHz. Berkeley Audio Design

The ability to choose either interface is particularly useful with reference DACs such as the Berkeley Alpha DAC Series 3 and Series 3P, which provide both AES/EBU and true 75Ω BNC inputs.

Purpose-Built for Music Servers

The Alpha USB Series 2 is designed to work with Linux-based music servers, Apple Mac and Windows PCs.

Berkeley specifies Linux compatibility with ALSA 1.0.23 or later and the ability to select the appropriate output device. Mac systems running Snow Leopard or later interface directly with the unit, as do Windows PCs running Windows 10 release 1703 or later. Berkeley Audio Design

For a dedicated high-end music server, the signal path becomes:

Music Server → USB → Alpha USB Series 2 → AES/EBU or BNC S/PDIF → DAC

This allows the server's USB output to be used while keeping the USB receiver and associated electrical environment outside the DAC chassis.

Ideal Partner for Berkeley Alpha DACs

Berkeley's DAC architecture intentionally avoids incorporating a conventional USB input. The Alpha USB Series 2 provides the bridge between a USB music server and Berkeley DACs equipped with AES/EBU and BNC S/PDIF inputs.

That makes it especially relevant with the Alpha DAC Series 3, which accepts 24-bit/192kHz PCM through AES/EBU, dual 75Ω BNC S/PDIF and Toslink. Berkeley Audio Design

The separate-interface approach allows Berkeley to optimize USB reception and isolation in one chassis while keeping the DAC focused on conversion, precision clocking and analog output.

Simple Front-Panel Operation

The Alpha USB Series 2 is intentionally straightforward to operate.

A front-panel Output Select switch chooses S/PDIF or AES output, while a status LED indicates operating condition:

Green — USB Lock
Amber — Standby Berkeley Audio Design

No additional signal processing, display system or unnecessary control circuitry is required.

Dedicated Linear Power Supply

The output master clocks and digital line drivers are powered by the Alpha USB Series 2's isolated linear power supply, independent of the USB-powered input circuitry.

The unit accepts 100V, 120V or 240V AC at 50/60Hz through a standard IEC inlet and consumes just 3 watts. Berkeley specifically states that the Alpha USB Series 2 is designed for continuous operation. Berkeley Audio Design

Berkeley Audio Design Alpha USB Series 2 Technical Specifications

Berkeley still provides the Alpha USB Series 2 Revision 2.0 User Guide through its current support/download section, and the product remains part of Berkeley's current product portfolio. Berkeley Audio Design

Alpha USB Series 2 vs. Alpha USB Reference Series

The Alpha USB Reference Series builds directly on the Series 2 architecture. Both provide asynchronous USB Audio 2.0, extensive input-to-output isolation, separate linear power for the digital output stage, selectable 110Ω AES/EBU and 75Ω BNC S/PDIF, and maximum resolution of 24-bit/192kHz. Berkeley Audio Design

The Reference Series advances the design with ultra-low-phase-noise reclocking technology derived from the Alpha DAC Reference Series 3P, along with increased enclosure mass and additional vibration isolation. The Reference chassis is 5.38 inches deep and weighs 2.8 pounds versus the Series 2 at 5 inches and 2.5 pounds. Berkeley Audio Design

The important distinction for the Shopify pages is that the Reference Series does not offer a higher PCM sampling rate. Both stop at 24-bit/192kHz. The Reference model's advancement is in clocking, time-domain accuracy, mechanical isolation and overall implementation.

Alpha USB Series 2 at The Grid HiFi

The Berkeley Audio Design Alpha USB Series 2 is an ideal solution for integrating a USB-equipped music server with a DAC optimized for AES/EBU or true 75Ω BNC S/PDIF. Its combination of asynchronous USB, extensive electrical isolation, precision output clocking and dedicated linear power makes it far more than a basic USB converter.

Pair it with the Berkeley Alpha DAC Series 3 or Series 3P, or use it to optimize the digital connection between a compatible music server and another high-performance DAC.

The Grid HiFi can configure the complete digital front end around the correct USB, AES/EBU or BNC connection, music server, DAC, amplification and system architecture.

Considering the Berkeley Alpha USB Series 2? Call The Grid HiFi at (713) 218-8120 to build the complete digital front end around it.