Audio Precision APx500 Flex audio analyser

Audio Precision logo




Hardware-based Audio Analysers button



APx500 Flex Audio Analyzer


Combining the power and versatility of APx500 measurement software with 3rd party audio interfaces

The APx500 Flex audio analyzer—comprised of APx500 measurement software and an APx500 Flex Key—allows you to select the ASIO*-capable audio interface of your choice to use along with AP’s versatile and powerful APx audio measurement software. Start with the measurement options you need now, with the freedom to add additional measurements as your test requirements evolve. The APx500 Flex brings Audio Precision innovations such as one-click measurements, code-free automation and sophisticated reporting to off-the-shelf audio interface hardware solutions.

Across all measurements, the APx500 user interface is fast and intuitive. Just click to select a measurement, then click to add a filter. Drag limits to set pass/fail points right on the results graph. Effortlessly specify computations for derived results. Add defined measurements in a series and run them in an automated procedure called a Sequence. The APx generator can output steady tones, twin tones, sweeps, chirps, multitones, or play WAV files as arbitrary waveforms.

Repetitive bench tests and production testing can easily be automated with the built-in measurement sequencer and saved as a project that can be used with any APx analyzer. Production Test mode provides an optional simplified operator interface with multiple run statistics, created and supervised by a manufacturing engineer. Access the API if you prefer: documentation for VB.NET, C#.NET, MATLAB and LabVIEW is included.


But what, exactly, is APx500 Flex?

The APx500 Flex audio analyzer is Audio Precision’s APx500 measurement software operating independently of an AP hardware analyzer, with licensing controlled by an APx500 Flex Key. In lieu of a purpose-built analyzer, Flex can be paired with ASIO*-capable third-party audio interfaces to create a cost-effective solution for a variety of acoustic and electrical test applications. Measurement scenarios where hardware performance requirements are secondary to test system price—such as production line test of speakers, headphones and microphones—are ideal candidates for Flex. APx500 Flex allows users to leverage test development done in the R&D cycle through the ability to import project and template files developed for AP hardware analyzers, thereby reducing test development time and maintaining consistency in test methodology across the organization. APx500 Flex also makes for a powerful, portable audio measurement system for application engineers and QA technicians on the go.







APx500 Flex is compatible with ASIO-capable audio interfaces. Choose the interface product that matches your budget and your application’s performance requirements.


Software licensing for APx500 Flex is facilitated by the APx500 Flex Key. Move your measurement licenses from one computer to another simply by moving your APx500 Flex Key.


Create custom interfaces and application-to-application automation using the comprehensive APx API. Extensive documentation and examples are provided for Visual Basic.NET, C#, MATLAB, LabVIEW, and Python. Projects and automation can be shared with other APx units anywhere in the world.

Common Software Platform

From a practical perspective, APx audio analyzers use a common software platform, making tests and results easier to share. All settings for a test are saved in a single project file, making it easy to replicate test setups between R&D and production facilities anywhere in the world. Project files are compatible with APx500 Flex. B Series, Legacy APx instruments and each project is self-contained, so there’s never any worry about dependencies or broken links. Users can even embed waveform files and images within a project file.

For sharing measurement results with customers, contract manufacturers or management, APx automatically generates rich graphic reports, with highlighted pass / fail limits and options to export as PDF, HTML, Excel, CSV, RTF or MATLAB files.

APx500 Flex Base Configuration (APX-FLEX-2CH):

  • 2 channel ASIO interface
  • File Analysis
  • Sequence Mode
  • Input Signal Monitors (including FFT monitor)
  • Level & Gain
  • THD+N
  • Loudspeaker Production Test (including Rub & Buzz)
  • Stepped Frequency Sweep
  • Pass / Fail Measurement
  • Signal Acquisition Measurement
APx 500 Flex

Configuration & Options

APx500 Flex continues the APx Series’ tradition of flexibility and configurability. In its base configuration, Flex is configured for two channels and includes a core set of fundamental measurements and functionality: File Analysis, Sequence Mode, Input Signal Monitors (including FFT Monitor), Level & Gain, THD+N, Loudspeaker Product Test (including Rub & Buzz), Stepped Frequency Sweep, Pass / Fail, and Signal Acquisition measurement. Configuration options for four or eight channels are also available, along with a trio of Flex Packs that each offer different groups of more advanced measurements. Perceptual audio measurements—including ABC-MRT and POLQA—can likewise be used with Flex. Finally, for the user that needs the base configuration plus just one more measurement, APx500 Flex has an à la carte menu of measurements from which to choose.

3rd Party Interfaces & APx500 Flex Compatibility

Any ASIO*-enabled audio interface should suffice with APx500 Flex. However, AP has verified the compatibility of three different audio interfaces—the RME Fireface UC, Lynx Aurora (n), and Lynx E22—and configuration templates for these devices are included in APx500 software v5.0.2. Each of these verified compatible interfaces offer quality analog I/O (<90 dB THD+N, 192 kHz SR) and stable drivers with consistent delay. Please contact the manufacturers, or their authorized resellers, for more information.

(*Audio Stream Input/Output (ASIO) is a computer sound card driver protocol for digital audio, providing a direct access, low-latency and high fidelity interface between a software application and a computer's sound card.)

What About AP Hardware?

APx500 Flex paired with an ASIO*-capable audio interface is an ideal test system for applications where cost sensitivity intersects lower performance requirements (e.g., ~90 dB THD+N and <10 Vrms maximum input level). For more demanding applications, where “demanding” can include challenging performance specifications, calibrated hardware, high-reliability requirements, digital I/O options such as PDM, and unique, hardware-dependent measurements like jitter, APx500 B Series audio analyzers remain the best choice for developers, design engineers and test technicians everywhere.


“Delivering configurability and flexibility, both in hardware and software, to our customers has been core theme of our APx Series analyzers since their introduction,” stated Mike Flaherty, Audio Precision Chief Executive Officer. “The APx500 Flex audio analyzer demonstrates that mindset is alive and well as we bring the power and versatility of our measurement software to price-sensitive applications around the globe.”


The APx500 Flex audio analyzer is available now, with the two-channel base configuration. As with all other new APx analyzers, APx500 Flex ships with the current version of software and one year of software maintenance, effectively licensing that Flex Key for the next APx version when it is released, as well as any minor releases that occur between versions.


  APx 500 Flex key   Learn_More_button_APblue