The Zen Amplifier — Nelson Pass / 1993

I. "What is the sound of one transistor clapping?" There are two most essential principles to audio amplifier design. The first is simplicity. The second is linearity. Einstein said, "Everything should be made as simple as possible, but no simpler." Simplicity is a common element of the best and most subtle designs. It is preferred for purely aesthetic reasons, but also because fewer elements color the sound less, and lose less information. Many audiophiles, including myself, are willing to sacrifice other areas of performance to achieve the intimacy with the sound available through a simple circuit. An amplifier should be… More...

Zen Variations 4 — Nelson Pass / 2002

The Penultimate Zen is the sum of several incremental improvements to the original Zen amplifier of 1994. Eight years just flies by, doesn’t it? These improvements are contained in parts 2 through 4 of the Zen Variations, and is likely the last version of this amp, although by no means the end of the variations on the theme of single stage amplification. In part 2 we developed an improved active current source load for the single gain device which is at the heart of the amplifier. Originally designed for the Aleph amplifier series, this current source doubles the output current… More...