RDL AFSH1 Stereo Headphone Amplifier

Herman # RDLAFSH1

This item has been replaced by DSH1 Stereo Headphone Amplifier.



The AF‑SH1 is used in applications requiring headphones of any impedance to be driven from consumer or professional audio sources. The module mounts conveniently in a precut opening in a wood or metal enclosure or in various RDL mounting accessories. The AF‑SH1 is a dual channel headphone amplifier with balanced/unbalanced left and right inputs. Each input accepts operating levels between ‑20 dBV and +20 dBu. Two recessed slide switches located on the side of the rear enclosure are set prior to mounting the module. One switch is provided for setting the input sensitivity. The mode switch selects between stereo and mono operation. In the mono position, the left input is used to drive both output channels. When the module is used in a monaural system, only the left channel input must be wired. The front panel level control is a long‑life potentiometer controlling matched VCAs. Audio does not pass through this control, assuring years of noise‑free level adjustment. The output amplifiers deliver more than 50 mW into either high or low impedance headphones through a durable, metal 1/4" (6.3 mm) standard headphone jack. Module operation is from a 24 Vdc ground‑referenced power supply. It can also operate from a 12 Vdc supply with a 6 dB reduction in headroom and a maximum output power of 10 mW.

  • Panel‑Mounted Headphone Amplifier
  • Wall‑Mounted Headphone Amplifier
  • Integral Long‑Life VCA Stereo Level Control
  • Balanced or Unbalanced Inputs
  • Switch‑Selectable Input Sensitivity
  • Switch‑Selectable Mono (Left) or Stereo Operation
  • Amplifier To Drive High or Low Impedance Headsets
  • Convenience of APPFLEX™ Mounting Possibilities

Inputs (2):

10 kΩ balanced or unbalanced bridging

Input Level:

+4 dBu nominal (Low input sensitivity);
‑15 dBV nominal (High input sensitivity)

Maximum Input Level:

+21 dBu (Low input sensitivity);
+3 dBu (High input sensitivity)

Output Signal (normal rated):

10 mW into 100 Ω

Output Signal (maximum):

50 mW into 100 Ω


< 0.5% @ 1 kHz

Frequency Response:

30 Hz to 20 kHz (+/‑ 2 dB)


< ‑70 dB below normal operating level


User‑adjustable on front panel
18.5 dB (maximum, High input sensitivity);
Unity (maximum, Low input sensitivity)


> 60 dB (50 to 120 Hz)


Below noise floor (20 Hz to 20 kHz)

Power Requirement:

GROUND‑REFERENCED 24 to 33 Vdc @ 50 mA

Ambient Operating Environment:

0° C to 55° C


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