With the advent of far more desktop media editing, often in large open-plan offices, more and more users are forced to use headphones for monitoring their work. This design, instigated by a request from a major broadcaster, provides optimum sound quality from a personal computer, connecting to the line output of the sound card and bypassing the headphone amplifier on the card. Hardware level and mono controls are provided for operational convenience, as well as rugged, full-size and miniature headphone sockets.
The front panel of the standard Canford extruded box has a 6.35mm 3-pole jack socket, A-gauge or B-gauge depending on model, and a 3.5mm stereo socket wired in parallel, fed after the rotary volume control and a toggle switch selecting between mono or stereo operation. In the mono mode, the inputs are summed and fed to both channels of the output jacks. An LED indicates the presence of power.
The rear panel has a 3.5mm, stereo jack socket for the input connection and a 2.1mm co-axial inlet for DC power.
Inputs: -20dBu nominal, 120kohms. Gain: 30dB. Response: 20Hz-20kHz, +/- 1dB. Distortion: 0.2% maximum, +10dBu, 600 ohms. Noise: Better than -65dBu, maximum volume. Output: +12dBu maximum (into 600 ohm load), 50ohms, to suit headphones 25 ohms to 2kohms. Power source: 12V-18V DC, 45/55mA maximum at 12/18V. Dimensions: 107 x 93 x 50mm, not including control knobs. Weight: 300g.
Application note:
The headphone amplifier requires a source of DC power. Suitable power supplies are available, but not included.
Optional accessories: Suitable UK AC adapter is 23-978.