The New HPA-1 Features Class A-Biased, Fully-Discreet, Direct-Coupled MOSFET Output Stages
Auburn, CA, November 23, 2015 - Since 1991, the name Pass Laboratories has been synonymous with innovative leadership in amplifier circuit design, so it comes as little surprise that what distinguishes Pass Labs' new HPA-1 Headphone Amplifier from countless contenders in the general onslaught is that the HPA-1 was designed on a "clean sheet of paper" as though it were to be used as a power amplifier.
Pass Labs' HPA-1 Headphone Amplifier is capable of delivering full-range dynamics across the entire frequency range, even when driving headphones that present difficult loads in terms of impedance, power consumption or both.
Pass Labs' designers knew that in order to stand out from the crowd, and satisfy their demanding customer base, the HPA-1 had to establish higher standards for audio performance. That has been accomplished first, by the conceptual approach of designing the HPA-1 as a real Class-A power amplifier, and not as an accessory offering only incremental performance gains. Second, by cutting no corners in circuit design, while omitting unnecessary frills. Thirdly, by sparing no necessary expense in execution.
The foundation of the HPA-1's engineering is a custom, low-noise shielded toroidal power transformer feeding a discreet low noise regulated power supply for the audio circuits. The importance of the power supply is often overlooked and plays a large part in overall performance of the amplifier. The HPA-1's amplifier circuits are low-feedback, wide-bandwidth discreet designs employing J-Fet input stages and Class A-biased direct-coupled MOSFET output stages. The HPA-1 easily drives headphones presenting loads from 15 to 600 Ohms, particularly excelling on planar headphone designs. The sound is rich and detailed.
The HPA-1 has a single high-quality headphone jack on its front panel, two sets of single-ended analog inputs via RCA jacks on the rear panel, and also a set of switchable "Preamp" line-level output jacks on the rear panel. There are no compromises with the HPA-1 when used as a stereo preamp and it will compete against contemporary preamplifiers. The rear panel holds the power switch and fuse. Volume control is via a hefty rotary knob connected to an ALPS Potentiometer. The other front-panel controls are three pushbuttons, to select inputs or to engage the Preamp output.
The substantial casework is the customary and well-recognized brushed aluminum shared with other Pass Laboratories products. Dimensions are 4.5" H x 11" W x 13" D; weight is 14 lbs.
The HPA-1 is available now at US MSRP $3,500.