An introduction to computer audio
Although it is changing slowly, the audio world is not very computer minded.
If audio gear has a digital connection, it is SPDIF.
All PCs have USB but few (most of the time the multimedia models) have SPDIF out.
If you want to connect a PC without SPDIF to audio gear with SPDIF input only, a USB to SPDIF converter is the solution.
The information below is as supplied by the manufacturer's website.
Asynchronous USB to SPDIF converter.
USB class 2 compliant (24/192)
USB receiver by XMOS, Win driver by Thesycon.
Two independent low-jitter crystal oscillators.
Galvanically isolating using a high-speed transformer at the SPDIF output.
|USB Audio Class 2.0 compliant||Asynchronous synchronization mode
High Speed Bit Perfect Audio Data Stream up to 192kHz sampling rates
|Master clock||Super low jitter 2 external clocks|
|Sampling Frequency||22.5792mHz/24.576mHz for multiples of 44.1kHz/48kHz sampling rates|
|Resolution||Standard sample rates 44.1, 88.2, 176.4, 48, 96, 192kHz/24bits Audio|
|Input||1 USB 2.0, Type B connector|
|Processor||32-bit 500Mips XMOS processor|
|Outputs||Galvanic Isolated, Up to 192kHz sampling rates
1 COAX 75 Ohms, Gold Plated RCA Connector
1 AES/EBU 110 Ohms, Neutrik XLR Gold plated contacts
|Lock indicator||LED on the front panel|
|Platform Support||Customized Windows Driver : Windows XP, Windows Vista, Windows 7
Natively supported by Apple Mac OS X
|Dimension||100 X 36 X 100mm (WHD)|
Measurements by NwAvGuy
Great care was taken in the design of the Alpha USB to isolate the noisy computer/USB environment from the digital audio output. The USB receiver and processing are powered by the computer, while the output master clocks and line drivers are powered by a separate isolated linear power supply.
Two key factors combine to achieve the excellent audio performance of the Alpha USB - the unprecedented degree of electrical isolation between the USB input connection and the audio output and the very low noise/low jitter performance of the individually tested audio output master clocks.
Source: Berkeley Audio Design
A PVC pipe filled with silicon and some unknown parts.
We are not going to tell anyone what IC we use for the conversion and DAC because we want you to judge the USB Thingee by its sonic performance and not by the numbers and specs.
Input: asynchronous 24/192 USB (Xmos), driver for Windows
Sample Rates Supported: 44.1k, 48k, 88.2k, 96k, 176.4k, 192k up to 24bits
Master Clock Jitter: < 1.0 psec
Analog Output Level: 2V RMS Maximum (Single-ended RCA)
Frequency Response: 0hz to 96kHz
THD + Noise: -89db @ -1dBFS
Dimensions: 4.45"W x 2.9"H (including feet) x 5.25" D
Warranty: 5 Year Parts & Labor
USB to SPDIF converter
USB receiver: M2Tech - proprietary drivers for Win and Mac
Dual clocks for 44.1/88.2/176.4kHz and 48/96/192kHz
Supported Formats :
24/96 USB to SPDIF converter.
Probably adaptive mode.
Size: High 80.15mm x Width 20.4mm x Depth 18.1mm
Some measurements by Stereophile
USB to SPDIF converter using Hiface EVO drivers (bulk mode).
The Pico on Head-Fi
Modified HiFace 24/192 asynchronous USB - SPDIF converter
FAQ about hiFace
The biggest news is probably that M2Tech decided not to use their proprietary drivers but to using the native mode USB audio drives of the operating system.
It is UAC1 and UAC2 compliant so will work out of the box with Win, OSX and Linux.
For > 96 kHz you need a driver on Win as Win is not UAC2 compliant.
The receiver is by XMOS and the driver by Thesycon.
Asynchronous operation up to 192kHz is used in conjunction with proprietary drivers which allow for Kernel Streaming, Direct Sound and WASAPI operation.
Sampling frequencies (kHz): 44.1, 48, 88.2, 96, 176.4, 192
Resolution (bits): 16 to 32
Inputs: USB 2.0, supply, master clock
S/PDIF x2 (RCA & BNC)
24 bit/ 96 kHz asynchronous USB to S/PDIF converter
Optical and coax SPDIF out.
24 bit/ 192 kHz asynchronous USB converter
It has both coax and fully balanced digital outputs. Both are fully galvanically isolated.
Asynchronous USB converter.
24/192 USB class audio 2.
Driver for Win
- 1 x SPDIF (RCA)
- 1 x AES/EBU (XLR)
- 1 x Optical (Toslink)
Digital Audio Input
Digital audio output
The new dX-USB HD has
Digital Input : USB x 1 (USB input sampling : 24Bit/96Khz)
Digital Output : Optical x 1, Coaxial x 1, AES/EBU x 1
USB signal isolator : Analog Devices ADUM4160
USB power isolator : Analog Devices ADUM5000
Scientific Conversion’s Digital audio transformer for isolated 110ohm balanced and 750ohm unbalanced
Power : USB self power or external adapter
Reclocking circuit & TCXO 10ppm, WIMA, OSCON, 24K gold PCB
Main body size (WxHxD/mm) : 75 x 35 x 131
Optical, Coax, BNC, and XLR digital connectors.
Sample rates: 32, 44.1, 48 kHz
Audio format: linear PCM, 16 bits per sample