The Neurochrome HP-LOAD is a stereo (2-channel) dummy load intended for use in the testing of headphone amplifiers. 

The HP-LOAD features:

• Caddock MP900-series power resistors with ±1 % tolerance
  
• Wima MKP2 polypropylene capacitors
• Sensing of the DUT output voltage by a differential Kelvin connection
  
• Balanced output for easy interfacing to audio analyzers
• Audio Precision APx-500 compatible 5 V remote control input
  
• Minimum power handling: 8 W per channel
  
• Maximum operating voltage: 63 V RMS (100 V DC)

Technical Documentation

User's Guide

• Description
• Resources

• The HP-LOAD allows you to select the load resistance (12, 16, 20, 32, 50, 300, 600 Ω) and parallel load capacitance (100 pF, 200 pF, 500 pF, 1.0 nF, 4.7 nF, 10 nF) applied to the headphone amplifier under test. This allows for easy measurement of amplifier performance as function of load impedance. The parallel capacitance allows you to test amplifier stability with a reactive load. 

  The load impedance can be selected manually or by applying a 5 V logic signal to the control port on the rear panel of the instrument. The control port is compatible with the Audio Precision APx500 audio analyzers. The remote control allows you to perform automated testing across a wide range of load impedances.

  The output voltage of the amplifier under test is sensed differentially with a Kelvin connection and provided on XLR outputs.

  The HP-LOAD includes the following accessories:

  • 3.5 mm TRS to 4-pin XLR adapter
  • 4.4 mm Pentacon to 4-pin XLR adapter
  • 6.35 mm (¼") TRS to 4-pin XLR adapter
  • 9-pin to 4-pin XLR cable (1.0 m/3.3 ft, 250 pF) with gold plated connectors
  • 9-pin serial cable for APx-500 remote control (1.8 m/6 ft)
    
  • Power supply with US, EU, UK, and Australia plugs

• HP-LOAD Rev. 1.0 User's Guide: HP-LOAD_R1p0_UsersGuide.pdf

  Audio Precision APx500 HP-LOAD test script: HP-LOAD_Test.approjx