ASIO Interface for APx B Series Audio Analyzers
Direct connectivity to any PC audio interface

ASIO is a PC audio driver technology developed by Steinberg Media Technologies GmbH (and since adopted across the pro-audio industry) that allows audio software to communicate directly with connected audio hardware with extremely low latency, high channel count and bit-transparent transfer of data.

PC audio interfaces with installed ASIO drivers appear within the APx500 software as one of APx’s I/O options, with support for up to 16 bidirectional channels. All measurements and test sequences in APx may be used via the ASIO interface, allowing for complete characterization of the connected audio device. Quick Tip Video #139 – ASIO Configuration

ASIO device settings within APx500 audio measurement software (click to zoom)

ASIO and PC Audio
ASIO is widely used on Windows-based PCs for professional recording and production because audio interfaces that rely on the native Windows drivers may experience excessive latency and unwanted gain, EQ, distortion and resampling. Using an ASIO driver in a test & measurement situation ensures that it is the performance of the device under test being measured, not the effects of the Windows operating system interfering with the measurements.

ASIO and Audio Interfaces
High quality audio interfaces for PCs now embrace a wide range of digital I/O options and definitions, but nearly all employ ASIO drivers to provide bit-transparent data transfer with low latency to Digital Audio Workstation (DAW) software.

Examples include:
• USB audio interfaces
• Firewire audio interfaces
• High-performance PCI and PCIe soundcards
• MADI soundcards
• AES/EBU soundcards
• Virtual interfaces for networked audio

The APx ASIO interface allows you to connect directly to any of these technologies directly on the test PC, allowing for comprehensive testing of audio with no unnecessary components or conversions.

ASIO is standard for the B Series APx555, as well as the APx52x and APx58x B Series audio analyzers as part of APx500 v3.1 and higher. The APx515 B Series analyzer supports up to 16 channels of ASIO at one time (with v4.0 software or later; two channels only when using earlier APx software versions) and requires the ASIO software option (SW-ASIO) or one of the APx515 software bundles (SWB-2 or SWB-6).

With ASIO built in to APx500, measurements of ASIO-compliant audio interfaces may now be made directly on the PC running the measurement software, without passing through additional hardware.

Note: in order for APx500 to function properly, an APx analyzer must remain attached via USB.

Testing PC Audio Interfaces with ASIO
Complete testing of PC Audio Interfaces can now be performed, using signal paths that send or receive audio via USB or Firewire as well as those that employ the analog and digital I/O on the DUT itself. This allows the test environment to closely mirror the “real world” application of the DUTs.

A typical test set-up for ASIO-based testing

Virtually any configuration of DUT signal path can be realized and measured. Finally, manufacturers of PC audio interfaces can completely test their devices from end to end.

Comprehensive Audio Test
ASIO can be selected for both the analyzer inputs and outputs simultaneously, or ASIO can be paired with any of the other available I/O formats: analog (bal/unbal), AES or S/PDIF digital, Bluetooth, HDMI, or serial digital. Over 30 one-click audio measurements may be made, either individually or in an automated project. Features include weighting filters, and user-defined high- and low-pass filters, 1.2M point FFTs, real-time oscilloscope monitoring, custom reports, statistical calculations, and quasi-anechoic acoustic measurements.