The OBH-11 is a miniature audio amplifier, designed specifically to drive headphones (from 30 ohms to 300 ohms) from a line level source. The purpose is to eliminate the use of a full size amplifier for boosting the power, if only headphones are used.

An average output level CD player or Tuner can be connected directly to the input of the OBH-11
It would also work with a stand-alone pre-amplifier or integrated amplifier without headphone output, connected in the tape loop.

The volume control on the front panel is designed to control the output level. Input and Output connections. The OBH-11 has stereo phono sockets (RCA jacks) on the rear panel for input from any line level source, together with a DC power jack, for connection to a custom OBH power supply adapter. There is a single 1/4" (6.3mm) stereo headphone jack on the front panel. N.B. Only one source can be amplified as it only has one stereo input. Power Supply requirements. In common with all electrical appliances, the OBH-11 requires a power source, and a custom power supply is provided to run it, which must be connected to the unit via the DC inlet (2.1mm positive centre pin power jack) on the rear panel. Sound quality is greatly enhanced by using the regulated 24V OBH-2 High Grade Power Supply (as opposed to the standard OBH-1). The power supply may vary depending on country of use.

No expense has been spared to enable the OBH-11 headphone amp to faithfully reproduce a music signal. Only the highest quality components are used in its classic amplifier circuitry, to achieve low distortion and noise, with good stereo separation.

Great care has also been taken to match the output circuitry to the special requirements of modern dynamic headphones, providing an extremely flat frequency response. Audio bandwidth is limited by input and output coupling capacitors to prevent unwanted signals. .  THD 0.1% at 1 kHz at rated power
.  Signal to noise 65 dB

• Single 1/4 stereo headphone jack on front panel
• Dimensions - 2H x 4W x 4D; weighs 12 ounces