Reference USB audio playback bridge
The previous model of Hydra, the X+, has built its reputation based on excellent sound quality. From our perspective, it is time to move on, and offer a new interface, that we named usb audio playback bridge.
While raising the bar even more in sound quality and keeping the existing set of features precedently available, the new Hydra Z comes with a list of improvements that we’re happy to share. Among the changes are a complete redesign of the digital board, changes in the way the Hydra is powered, new output configuration, new chassis and many other refinements – please see below.
MORE FLEXIBLE The Hydra Z can be powered in 3 (three) ways :
TECHNICAL IMPROVEMENTS Hydra Z benefits from all the qualities of the X+, and even more. New clocking scheme allows shutting down one of the two main oscillators when not in use. By reducing the mutual interference between clocks, better phase noise performance can be obtained. The power supply section was moved to a different chassis for best results.
WORDCLOCK and MASTERCLOCK OUTPUT The Hydra Z can be additionally used as a wordclock or masterclock generator through its dedicated BNC output. In total there are available 6 (six) outputs, including the low-jitter wordclock/masterclock output for direct synchronizing external d/a converters. The output wordclock is the sample clock (44.1KHz - 384 KHz) or 512xfs (22.5792 MHz or 24.576 MHz). The other 5(five) are : SPDIF Coaxial, SPDIF BNC, AES/EBU, I2S, TOSLINK.
IMPROVED CHASSIS The new Hydra has a full aluminium chassis, with a 10 mm thick front panel. All connectors are conveniently placed on the back panel.
ISOLATION A 5KV isolation barrier is used to prevent any leakage of the noise from PC to your sensitive audio system. The USB isolation for audio devices is nothing but tricky. If you choose to use USB isolators, then sample rate will become limited, which is not an option. If you choose to isolate the output, you are adding significant amounts of jitter to the signal. By using a clever circuit topology, the Hydra design avoids these two bottlenecks. The isolation is placed between the ARM processor and the FPGA audio core, therefore not limiting the bandwidth. Being before the clocks, its jitter contribution becomes irrelevant.
ARM PROCESSING All USB audio transactions are made through a powerful ARM3 processor. Therefore Hydra Z supports any sample rate available (384k PCM, DSD128) while being future-proof for any extension.
FPGA TECHNOLOGY As all AUDIOBYTE digital products, the Hydra Z uses cutting edge, custom digital processing developed into a Xilinx Spartan6 field-programmable gate array. The fpga is the “heart” of the Hydra. This advanced programmable circuit is offering a bit-transparent processing and signal conditioning to all outputs. It also gives the ability of the Hydra to output raw dsd audio streams.
AUDIO GRADE CLOCKS Unlike other products which only specify "low jitter clocks", here is exactly what you will find inside : 2xCCHD-950/957 type from Crystek. These are real audio grade clocks. You can check real graphs for them here. These clocks are system masters. In order to remove any jitter induced by the FPGA circuit itself, special retiming is applied just before the Hydra Z outputs.
COMPONENTS AND LAYOUT Careful PCB layout is often neglected in the rush of getting a product quickly into the market. The Hydra Z design time took lots of work until everything came into the right place, until the shortest routing paths, the best decoupling places, the less interference and crosstalk placement for the components are found. Selected quality components (active and passive) are used for guaranteed long-time performance.
EXTERNAL POWER SUPPLY For best results you can use the Hydra Z with the dedicated Hydra ZPM power supply.