Bryston BDP-1 digital audio player
I found a more relaxed Tanner at the 2010 CES. This time, he'd borrowed an Auraliti L-1000 digital file server ($3000 at www.auraliti.com), a box with no front-panel controls, no display, no hard drive, no fans, and no CD drive. Instead of a Windows operating system, the L-1000 ran a stripped-down version of the Linux open-source operating system. Its simplicity of design solved the reliability problems Tanner had encountered the year before.
Then and there, Tanner decided to ask Auraliti to help Bryston create a simple digital music file player. The result is the BDP-1.
It should come as no surprise that Bryston's BDP-1 digital file player resembles the basic Auraliti L-1000 in that it has a soundcard, motherboard, USB port, and power supply. Though there is a display, there are no fans, no CD drives, no keyboards, no DAC circuitry, and no built-in routers to produce noise, RF interference, or heat, or to tax the player's central processing unit with multitasking demands. Like a CD transport, the BDP-1's only job is to output a digital stream from its S/PDIF BNC or AES/EBU XLR outputs. The open-source Linux software was selected to ensure the BDP-1's long-term viability. The BDP-1 differs from the Auraliti L-1000 in two ways: it has AES/EBU output in addition to S/PDIF, and a front-panel display and keypad to control playback, the latter freeing the BDP-1 from the L-1000's dependence on a network.
The BDP-1 accepts uncompressed AIFF and WAV music files, lossless FLAC files, and lossy-compressed formats such as MP3, stored on Windows-formatted USB drives. However, it will not work with Apple Macintosh-formatted disks. (This limitation may be fixed in future iterations of the player's operating system.)
Like the L-1000, the BDP-1 plays digital files from external flash drives or portable hard drives that can be plugged into one of its four USB 2.0 ports. When a file is selected for play, the BDP-1 first copies the file from the external drive to an internal buffer, thus avoiding the usual jitter problems when data are streamed directly from a USB port. The BDP-1's soundcard outputs the stream via the player's S/PDIF and AES/EBU ports to feed an external D/A processor. Bryston didn't include a TosLink output because its restricted bandwidth limited the player's output quality.
Removing the BDP-1's top panel reveals a simple circuit layout free of moving parts. The analog and digital power-supply circuit boards are kept separate, each with its own ground plane. The analog circuit's toroidal power transformer is just behind the left half of the front panel, while the digital circuit's power supply sits at the rear of the chassis. A ribbon cable carries power and control signals from the power-supply board at the rear of the chassis to the front panel's display, IR detector, and navigation keys. Two large cables run from the front two USB sockets down the middle of the chassis to the digital input board, which is also fed by the rear panel's USB ports. The two front and top rear USB ports share the same power source; the bottom rear USB port has its own supply, so power-hungry hard drives are best connected there. The right side of the BDP-1's chassis is filled with a multilayered printed circuit board (PCB) that runs the Linux operating system, stored on a plug-in 4GB compact flashcard along with the player's read-only BIOS. The large, surface-mounted central processing unit (CPU) chip occupies the PCB's center. A modified ESI Juli@ 24-bit/192kHz soundcard is mounted on the left edge of the motherboard.
The motherboard itself is made of double-sided epoxy glass populated with surface-mount components, polystyrene capacitors, and high-quality, 0.1%-tolerance metal-film resistors. Surface-mount and other gas-tight mechanical connections are used for signal circuits. I was told that the PCB traces were laid out to reduce coupling between signal channels. The BDP-1's layout, components, circuit boards, and wiring are the best I've seen in a home audio product.