Bride of Zen — Nelson Pass / 1994

This is the second installment of a trilogy of construction projects centered around the performance obtainable from absolutely minimalist circuitry. Part one described the Zen amplifier, a 10 watt single-ended class A power amplifier using a single MOSFET gain stage. In this piece we will examine its preamplifying mate, also a single gain stage MOSFET circuit. A lot of what I might say about this design has already been expressed in the Zen amplifier piece, and will not be repeated here. It is enough to say that I continue to be very intrigued by the sound of very simple topologies,… More...

Zen Variations 8 — Nelson Pass / 2005

Thanks to a nice person on the Pass Labs Forum ( www.diyaudio.com ), I became aware that high current power JFET transistors are again available. You can check them out at www.lovoltech.com which offers a small variety of high current N-channel vertical JFETs in TO-251 and TO-252 packages. They don’t hold a lot of voltage 20-24 volts) or dissipate lot of power (69 watts, derated at 1.8 watts/degree), but they do deliver up to 100 amps peak. Clearly designed as switches, they nevertheless offer a linear operating region and are attractive for audio amplifier design. Small signal JFETs are routinely… More...