APx500 Flex Audio Analyzer

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.

APx500 Flex Audio Analyzer

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.


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


APx500 Flex continues AP’s tradition of highly-configurable measurement solutions. Select measurement options based upon your test requirements, with the ability to purchase individual measurements or value-priced Flex Packs.


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
• Loudspeaker Production Test (including Rub & Buzz)
• Stepped Frequency Sweep
• Pass / Fail Measurement
• Signal Acquisition Measurement

Additional measurements, available either as individual options or as part of APx500 Flex Packs, are listed in the Options tab or the APx500 Flex audio analyzer data sheet.


Determined by user-selected audio interface (sound card)



• Microsoft Windows 10, or Windows 8, 64-bit operating systems.

• PC with 2 GHz or faster multi-core processor (2 or more cores)
Note: the Intel Atom dual-core processor does not have sufficient performance to run APx software.

• 2 GB or more RAM (4 GB or more recommended for Windows 8).

• More detailed information is available on our AP Software and Windows Compatibility chart


• System performance is sensitive to processor speed; faster processors will yield faster results.

• APx500 is data intensive and it is recommended that other data-intensive applications not be run concurrently. This includes Audio Precision AP2700, APWIN or ATS.

Yderligere information






This option expands APx500 Flex to support four channels of audio measurement and provides Sequence Mode, input signal monitors, file analysis, level & gain, loudspeaker production test (including rub & buzz), pass/fail, stepped frequency sweep, signal acquisition and THD+N.


This option expands APx500 Flex to support eight channels of audio measurement and provides Sequence Mode, input signal monitors, file analysis, level & gain, loudspeaker production test (including rub & buzz), pass/fail, stepped frequency sweep, signal acquisition and THD+N.



Flex Pack 2 includes the following measurements: crosstalk, crosstalk sweeps, DC level, DC level sweep, DUT delay, frequency, frequency response, interchannel phase, level ratio, measurement recorder, noise, noise recorder, Q-peak noise, SNR, SINAD, and stepped level sweep.


Flex Pack 3 includes the following measurements: continuous sweep, digital error rate, dynamic range (AES17), IMD, IMD frequency sweep, IMD level sweep, input sample rate, maximum output, maximum output (CAE-2006), multitone analyzer, regulated frequency sweep, and signal analyzer.


Flex Pack 4 includes the following measurements: acoustic response, bandpass frequency sweep, bandpass level, bandpass level sweep, cumulative spectral decay, impedance/Thiele-Small, modulated noise, polar plots, and transfer function.


In addition to Flex Packs, APx500 Flex measurement options can be purchased individually, allowing users to configure their test system specifically for their application requirements. Measurements can be added to an APx500 Flex Key when ordering a new APx500 Flex analyzer or they can be delivered electronically to an existing APx500 Flex Key. Please consult the APx500 Flex data sheet for a complete list of measurements.


Perceptual Audio Test: POLQA (SW-POLQA-2)
Perceptual audio measurement returns a subjective assessment of speech quality using the next-generation POLQA algorithm for wide-band speech devices or devices with acoustic coupling. (Successor to PESQ with support for HD Voice, 3G, 4G/LTE and VoIP technologies)

Perceptual Audio Test: PESQ (SW-PESQ)
Widely-used, enhanced perceptual measurement for subjective assessment of speech quality on low-bandwidth devices. (PESQ algorithm)

Speech Intelligibility: ABC-MRT Measurement (SW-ABC-MRT)
The APx ABC-MRT plugin is a software option for APx500 audio measurement software that provides speech intelligibility measurement based upon the ABC-MRT speech processing algorithm developed by the Institute for Telecommunication Sciences (ITS) of the United States National Telecommunications and Information Administration (NTIA).

Speech Intelligibility: Speech Transmission Index (SW-STI)
SW-STI is a plug-in for conducting Speech Transmission Index (STI) measurements using the STIPA method.