AP - The Recognized Standard In Audio Test

AP High Performance Audio Analyzer & Audio Test Instruments : APX


Comprehensive HDMI and
Blu-ray Audio Test



The APx HDMI option (HDMI+ARC) for the APx555, APx525 and APx585 allows engineers to measure HDMI audio quality and audio format compatibility on devices such as surround sound receivers, set-top boxes, HD TVs, smartphones and tablets, and DVD or Blu-ray Disc™ players. Connections are provided for source and sink devices, as well as additional HDMI connections for auxiliary video input and a monitor output.

Support for the Audio Return Channel (ARC), a part of the HDMI 1.4 spec, adds the ability to test both ARC audio quality and connectivity on receivers and TVs that support it.

All standard audio measurements are available including level, SNR, distortion, phase, crosstalk, group delay, and others. The APx500 software is capable of taking 14 measurements in only 7 seconds, automatically generating a report of results, and saving all test settings in a single, sharable project file. Real-time signal monitors include residual THD+N in oscilloscope view and a 1.2M point FFT.

Verifying Dolby & dts encoded audio

In addition to generating linear / PCM audio streams, APx can stream lossless formats (such as Dolby TrueHD™ and dts-HD Master Audio™) and compressed formats (such as Dolby Digital™ and dts Digital Surround™) from pre-encoded audio test files.

This feature makes it easy to troubleshoot component compatibility and downsampling / downmixing / transcoding issues.

Streaming of .wav, .ac3, .dts, and .cpt over the SPDIF, TOSLINK, and AES/EBU digital outputs is also supported.


An additional set of HDMI connectors (also utilized for AUX In and Monitor Out) are provided for Audio Return Channel transmit and receive. In addition to full audio and metadata analysis capabilities, APx500 can send and receive CEC commands, allowing observation and troubleshooting of ARC connection negotiations. The regular HDMI connectors may also be used simultaneously, making it possible to send a test signal to a device over HDMI and to receive it back over ARC for analysis.

Smartphones and tablets

The APx520 with HDMI and Bluetooth, or the APx525 with DSIO, HDMI, and Bluetooth options are the perfect analyzer for testing every input and output on a smartphone or tablet. It provides two analog channels, which is all that’s needed for these devices, plus it supports up to eight channels across HDMI.

Blu-ray audio

Because Blu-ray and other disc players cannot accept an incoming audio stream, test signals must be played from disc. Every APx with the HDMI option includes a Blu-ray Disc with high-resolution versions of a wide selection of audio test signals.

Viewing and editing HDMI E-EDID data

An EDID is a ROM inside a piece of HDMI sink equipment such as a TV that informs the HDMI source of what audio and video formats the sink supports. For audio, that includes the number of channels, types of codecs, and sample rates.

EDID must be set up correctly or the source may send formats that the sink can’t handle. If the sink doesn’t report its capabilities properly, the unit is likely to have interoperability problems.

APx provides the ability to view and save the E-EDID of a device connected to the instrument’s source connector. In addition users can arbitrarily edit the E-EDID that the instrument’s HDMI sink presents to a source device under test.

APx HDMI EDID configuration files
APx with HDMI supports multiple EDID configurations. These .edid files are pre-configured for various audio formats, including encoded audio such as DTS.

Download EDID configuration files


Video and third party support

The APx HDMI option has a basic video generator. The user can generate a single color video test signal and control the resolution (up to 1080p), the color of the image, and the color depth (including deep color).

Use of third party video pattern generators is supported by the “Pass External Video Through” option. When an external video signal is provided, APx combines it with the audio stream from the APx’s generator and outputs a single audio/video stream.

The system also forwards E-EDID and CEC data transparently between the device under test and any device connected to AUX IN.

The APx itself does not analyze video; however, all signals delivered to the sink are mirrored to the AUX OUT monitor connector. This allows the user to send the video signal to an external video analyzer or monitor the signal on a display.



HDMI+ARC Upgrade

Upgrade your exisiting APx585 HDMI module to HDMI+ARC and receive a special $2500 trade-in credit.

What others are saying

"Imagine for the first time in the history of this industry, you can simply plug an AV receiver’s HDMI input directly into this machine and test every aspect of its audio performance."

Gene DellaSala | Audioholics


"Plugfests are extremely valuable. But, it’s just a first—or possibly last—step in testing."

Tom Kite, AP’s VP of Engineering, on testing HDMI audio | Test & Measurement World



Fig 1. The APx500 EDID Editor.

Specifications and Features

  • HDMI 1.3a Source and Sink
  • HDMI 1.4a ARC (Audio Return Channel)
  • HDMI audio Layout 0 or 1
  • Generates linear PCM audio on up to 8 channels at 44.1, 48, 88.2, 96, 176.4, and 192 kHz up to 24 bit
  • Generates lossless formats such as dts-HD Master Audio at 48, 96 and 192 kHz
  • Generates compressed formats such as Dolby Digital and dts Digital Surround
  • Generates and displays E-EDID values
  • Generates a video test signal at all HDMI standard resolutions, color depths (incl. deep color), and refresh rates
  • Auxiliary interfaces for third party video test equipment
  • Full support for HDCP encryption on source and sink
  • Bit-for-bit verification of digital data reproduction
  • Display and set Audio Infoframe and Status Bits

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