|A Power Amp
for Headphones: Pass Labs' HPA-1
ass Labs new HPA-1 headphone
amplifier ($3500) is said to be "capable of delivering full-range dynamics across the
entire frequency range, even when driving headphones that present difficult loads."
The HPA-1 drives headphones with loads from 15 to 600 ohms, "particularly excelling
on planar headphone designs." In concept the HPA-1 is a class-A power amplifier whose
foundation is a custom, low-noise, shielded toroidal power transformer feeding a low-noise
regulated power supply. The HPA-1s amplifier circuits are low-feedback,
wide-bandwidth designs employing J-FET input stages and class-A direct-coupled MOSFET
by The Audio Beat |
December 2, 2015
The HPA-1 has a single 1/4" headphone jack on its
front panel, two sets of single-ended analog inputs via RCA jacks on the rear panel and a
set of switchable line-level output jacks, so the HPA-1 can be used as a stereo preamp.
Volume control is via a large knob connected to an ALPS potentiometer. The other
front-panel controls are three pushbuttons used to select the input or engage the
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