HPA Jr The HPAJr Headphone Amplifier is a compact, battery / external dc powered unit designed to interface your favorite full-sized professional headphone to a variety of audio input sources. Now you won't be limited to small, poor quality "in-ear" or "walkman" type headphones for your monitoring or listening needs.

The HPAJr will allow you to drive headphones of many impedances to more than adequate listening levels with a full, rich sound not obtainable at low output levels or with lightweight "personal" earpiece / headphones.

You can use the HPAJr for such professional purposes as increasing monitor levels from: mixers, portable VCR's, tape recorders or R-DAT's; personal listening to keyboards and synthesizers or monitoring of home studio gear. Compact and durable, the HPAJr comes with a sturdy belt clip for complete portability.


Frequency Range:
  • 5Hz - 30kHz.
  • Operational Modes:
  • Stereo or Mono selectable.
  • Input:
  • " Phone jack. 50k ohm impedance.
  • Input Sensitivity (Selectable):
  • @ -10dBm = 245mV
  • @ -30dBm = 25mV
  • Output:
  • " Phone jack. 4 ohm - 600 ohm impedance.
  • Total Output Level:

    Power SupplyOutput ZOutput PowerOutput Voltage
    12V600 ohms120mW6V
    12V 8 ohms3W3.5V
    18V600 ohms160mW7V
    18V 8 ohms5W4.5V

    Power requirements:
  • Batteries - 2 @ 9V (alkaline preferred).
  • External - 12Vdc - 18Vdc @ 300mA via 3.5mm jack.
  • Approvals: - CE Mark
  • Emissions: - EN 55022 B - FCC Class B
  • Immunity: - EN 55024 B
  • Size (W x H x D); Weight:
  • 2-7/8" x 5" x 1"; 8 oz.
  • Case Material:
  • Painted aluminum.

    pdf Download in Adobe® PDF format.
    You will need a copy of the Adobe® Acrobat® Reader to view it.

    HPAJr Manual 19K unzipped.

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