High Sampling Rates with USBPre 2

For many specialized applications, sampling at rates higher than 48 kHz is a requirement. Some common applications for high sampling rates include:

• • acoustic test and measurement,
  • sound effects recording,
  • classical music recording,
  • environmental recording.

The USBPre 2 operates at sampling rates up to 192 kHz. The information below describes some of the sampling rate and bit depth limitations the USBPre 2 has in different operating environments.

Stand Alone Mode

When the USBPre 2 is operating in Stand Alone mode (without being connected to a computer), it operates at the sampling rate set by its back panel hardware DIP switches. Available sampling rates include:

• • 16 kHz
  • 32 kHz
  • 44.1 kHz
  • 48 kHz
  • 88.2 kHz
  • 96 kHz
  • 192 kHz

The USBPre 2 in Stand alone mode always operates at 24-bits. If it is connected to an input which only accepts 16 bits, the 8 least significant bits will be ignored (truncated). When  digital audio signals are used as inputs in Stand Alone mode the USBPre 2 will lock to the incoming rate and operate at that rate. There are no sampling rate converters on the USBPre 2.

Mac OS 10.5.8+

Mac OS versions 10.5.8 and greater support USB Audio Class 2.0 devices as Core Audio devices. This allows for connections at high sampling rates. USBPre 2 sampling rates supported in Mac OS 10.5.8 and greater include:

• • 8 kHz, 16- or 24-bit
  • 16 kHz, 16- or 24-bit
  • 24 kHz, 16- or 24-bit
  • 32 kHz, 16- or 24-bit
  • 44.1 kHz, 16- or 24-bit
  • 48 kHz, 16- or 24-bit
  • 88.2 kHz, 16- or 24-bit
  • 96 kHz, 16- or 24-bit
  • 176.4 kHz, 16- or 24-bit
  • 192 kHz, 16- or 24-bit

Either the operating system or a software application can control the sampling rate of the USBPre 2.

Windows XP, Vista, and 7

Windows does not support USB Audio Class 2, reverting instead to USB Audio Class 1. As a class-compliant device the USBPre 2 has a maximum sampling rate of 48 kHz in Windows. Supported rates include:

• • 8 kHz, 16-bit
  • 16 kHz, 16-bit
  • 32 kHz, 16-bit
  • 44.1 kHz, 16- or 24-bit
  • 48 kHz, 16- or 24-bit

To operate with higher sampling rates in Windows, devices require a dedicated driver, such as a dedicated ASIO driver, which is available as a separate download from the Sound Devices website. Click here to read more on the USBPre 2 ASIO driver for Windows OS.

iOS

The USBPre 2 can be used as an audio device in Apple's IOS version 3.2 with an Apple iPad. With the iPad, the USBPre 2 is limited to a maximum sampling rate of 48 kHz, since IOS accepts USB Audio Class 1 devices.