The HPA-1 is a Headphone Amplifier and Preamplifier
The HPA-1 is Pass Labs' first headphone amplifier. It was designed by Jam Somasundram, former director of engineering at Cary Audio. After he joined Pass Labs in 2013, Somasundram spent a year conceiving the HPA-1.
The HPA-1 is a Class A headphone amp that also functions as a preamplifier. Somasundram designed it as a preamp first. It's more like Pass Labs' power amps, and it's designed to drive all dynamic and planar magnetic headphones. After its release in 2014, the HPA-1 was named Headphone Amplifier of the Year by The Absolute Sound and Best Headphone Amplifier by HomeTheaterHiFi, and was named Amplifier of the Decade by Stereophile Magazine. Its lucious, tube-like sound has earned the HPA-1 many fans over the years.
- Designed as a power amplifier rather than a typical headphone amplifier to be able to drive low impedance planar headphones from brands like HiFiMan, Audeze, Dan Clark, and more.
- Works with headphones with impedances of 15 ohms to 600 ohms.
- Low feedback wide bandwidth discreet design.
- Class A direct coupled Mosfet output stage.
- Custom low noise Toroidal power transformer with a Faraday shield.
The front panel features:
- a single, locking Neutrik 1/4" headphone jack;
- a large volume control knob; and
- three buttons to select inputs or to engage the preamp output.
HPA-1 Headphone Amplifier Specifications
Sound Highlights: Neutral-warm, musical, big soundstage
Output power into 20 ohms: 3500mW
Output power into 300 ohms: 200mW
Sensitivity: 110dB SPL/1mW Sensitivity
THD + Noise: <0.005 at 1V out
Frequency response 10Hz-100k: 1dB
Input impedance: 50K ohms
Output impedance: <2 Ohms
Power consumption: 6 watts
Dimensions: 4" H x 11" W x 13.5" D
Inputs: Two single-ended RCA
Output: One single-ended RCA (line), 1/4" TRS jack
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