Single Ended Class A — Nelson Pass / 1995

Single-Ended Class A amplifiers have certainly hit it big in the four years since we began testing the first Aleph 0. So is this just another audio fad, or is there something fundamental about this kind of design, justifying a revival of the old approaches to amplification? When I started designing amplifiers twenty-five years ago, solid state amplifiers had just achieved a firm grasp on the market. Power and harmonic distortion numbers were the important thing, and the largest audio magazine said that amplifiers with the same specs sounded the same. We have heard Triodes, Pentodes, Bipolar, VFET, Mosfet, TFET… More...

Balanced Zen Line Stage — Nelson Pass / 1997

The popularity of the Zen projects points out the interest in very simple linear circuits. They are intended to fuel that interest. The Zen, Bride of Zen, and Son of Zen have been explorations in how much objective and subjective performance can be achieved with a single gain stage. This extreme simplicity has an aesthetic appeal, which speaks to the purist in audiophiles, and the presumption that simple circuits sound better. At least one "objectivist" has complained (objected?) that the Zen projects do not measure up compared with more sophisticated and complex amplifiers. This is mostly true, but beside the… More...