This compact, self-contained headphone amplifier board is built around the Texas Instruments designed LM4881 Boomer® dual headphone amplifier IC. The LM4881 features high quality, Class AB output (up to 15.7 dB of gain) with minimal components and is able to operate with a wide array of power supplies from 8 to 24 VDC without the need for a heat sink.
Additional to its use as a headphone amplifier, this amplifier board may also be used as a preamplifier or a small loudspeaker power amplifier, with output of up 150 mW per channel at 8 ohms. An exceptionally low total harmonic distortion and noise rating of 0.1% @ 150 mW into an 8 ohm load ensures clean output with lower impedance loads. Distortion and noise are even lower for high impedance headphone loads; 0.02% @ 75 mW into a 32 ohm load.
Locations for the addition of screw-down wire terminals are provided for signal inputs and power outputs. A two-conductor screw-down terminal is included for power supply connection. See related items for two-conductor screw terminals. Gain settings are provided for each channel, as-is stereo 3.5 mm input and output jacks, as well as a 2.1 x 5.5 mm DC power jack.
Features and Specifications:
• Input power requirements: 8 to 24 VDC, 500 mA (minimum recommended current capacity)
• Powre output: 150 mW @ 8 ohms (0.1% THD+N), 120 mW @ 16 ohms (0.025% THD+N), 75 mW @ 32 ohms (0.02% THD+N)
• Frequency response: 20 to 20,000 Hz (±3 dB)
• Gain settings: 9.6 dB (low), 15.7 dB (high)
• Input impedance: 1.7k ohm (with gain set to high), 3.3k ohm (with gain set to low)
• Thermal shutdown protection circuitry built-in
• Dimensions: 3" L x 2" W x 5/8" H