Audio analyzer combines analog and digital domains

The APx516B from Audio Precision comes with built-in analog I/O and a slot that adds wired or wireless digital I/O.

With so many of today’s devices having audio capabilities, engineeers designing wired or wireless audio into a device need to verify audio quality. Audio Precision, well known for its audio analyzers, has introduced the APx516 audio analyzer that adds digital audio to its standard two channels of analog I/O.

The $6000 base model includes the two analog channels. A digital I/O slot lets you add wired and wireless digital audio, letting you test both audio producers and receivers such as Bluetooth devices. The digital I/O slot adds:

• Bluetooth core specification v4.2, HFP v1.7, HSP v1.2, AVRCP v1.4 and A2DP v1.3.
• PDM (pulse-density modulation) input and output, providing direct I/O, modulation, and decimation. A PDM16 module provides 16 PDM input channels.
• The digital serial I/O module provides a direct connection to chip-level interfaces such as I2S for testing audio analog-to-digital and digital-to-analog converters. It supports interface formats such as left justified, right justified, and DSP.
• The HDMI module lets you measure HDMI audio quality and audio format compatibility on devices that include surround sound receivers, set-top boxes, HDTVs, smartphones, tablets, and DVD or Blu-ray Disc players.
• A DIO module adds AES3, AES/EBU balanced digital I/O on XLR; unbalanced SPDIF digital I/O on BNC; and TOSLINK optical digital I/O.

The APx516B lets you analyze audio parameters such as frequency response, distortion, noise, linearity, and spectrum analysis. “That’s about 90% of the audio measurements that engineers make,” AP’s Daniel Knighten told EE World. Additional measurements include intermodulation distortion (IMD) and speech quality index.

In most cases, your audio testing will involve sources such as smartphones, tablets, TVs, power amplifiers, A/D and D/A converters, and so on. To test earbuds, you can use an ear simulator from Gras Acoustics to capture audio and send it back to the analyzer.

“We designed the APx516B for value,” said Knighten told EE World. “With engineers working at home or in other locations outside the lab, the APx516B, with its $600 starting price (analog only) lets just about every engineer have one.” In addition to bench applications, the APx516B can also serve as a production audio analyzer.

The APx516B works with Audio Precision’s APx500 audio software through a USB interface. Automation support includes .NET, Python, Labview, and Matlab.