The Well-Tempered Computer

An introduction to computer audio

Vendor specific

Some companies don’t use USB audio in isochronous transfer mode.
They implement their own solution using bulk mode transfer.
Bulk mode is asynchronous by design.

As it is bulk mode,

In case of isochronous mode it is exactly the reverse.

As long as the DAC is the only one connected to an internal hub, bandwidth is in general not the problem using USB high speed mode.

 

Inherent to a vendor specific solution is that he either supports your OS or not.
The advantage of USB audio is that it is natively supported by Win, OSX and Linux.
However in case of USB audio class 2 on Win you need a third party driver too.

Anyway this solution does audio over the USB without using the USB audio of the operating system.

John Kenny JKDAC32 €500

Modified HiFace asynchronous USB with 32/384 DAC - analogue RCA stereo output

The JKDAC32 has the following characteristics:
  • It's a modified I2S Hiface capable of 24/192
  • integrated with a 32/384 DAC (for those that prefer something other than the sound of an ESS DAC chip)
  • operates exclusively from 2 internal LiFePo4 (Lithium Nano Phosphate) batteries
  • completely portable - will run for >8 hours from fully charged batteries
  • Only USB input - standard USB type B input socket
  • Only RCA analogue outs
  • Outputs at standard 2V RMS (line level) for driving preamplifier or amplifier
  • internal battery charger - requires user supplied 9V or 12V DC supply
  • aluminium enclosure (Size in mm L:120 W:78 H:43)

 

M2Tech Young DAC $1,999.00

M2Tech Young

High-speed asynchronous USB D/A converter

 

Inputs:

1x USB (USB female Type B)

16, 24, 32 bits

44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384 kHz

 

2 x S/PDIF (RCA and 75 Ohms BNC)
1x AES/EBU (XLR)

16 and 24 bits, 44.1, 48, 88.2, 96, 176.4, 192


1x optical (Toslink)

16 and 24 bits, 44.1, 48, 88.2, 96

 

SNR: 121dB (A weighted, 192kHz, 24 bits, 20kHz bandwidth)
THD+N: 0.0003% (192kHz, 24 bits)


Drivers:

Windows 7/ Vista /XP

OSX 10.6 Snow Leopard - 10.7 Lion compliant

RME Fireface UC

 

  • 18 Input / 18 Output channels
  • 8 x Analog I/O
  • 1 x ADAT I/O or 1 x SPDIF I/O optical
  • 1 x SPDIF I/O coaxial
  • 2 x MIDI I/O
  • 1 x USB 2.0
  • 1 x Word Clock I/O
  • 2 x Mic Preamp with digitally controlled gain
  • Sample rates 32, 44.1, 48, 64, 88.2 kHz, 96 kHz, 128, 176.4, 192 kHz

Driver support

Windows XP (from SP2), Vista, Vista 64, 7: Full ASIO multi-client operation of WDM and ASIO 2.0. WDM (DirectSound) with stereo and multi-Channel support.

Mac OS X (10.5 or higher) Intel: Core Audio, Core MIDI.

Babyface

Using the same USB interface as his bigger brother.

  • 10 Input / 12 Output channels
  • 2 x Analog Input
  • 4 x Analog Output
  • 1 x ADAT I/O or 1 x SPDIF I/O optical
  • 1 x MIDI I/O
  • 1 x USB 2.0
  • 2 x Mic Preamp with digitally controlled gain
  • 1 x Hi-Z instrument input
  • TotalMix FX (with EQ, Reverb, Echo)

 


References

More technical information about USB audio can be found here.

© Vincent Kars January 2012