Audio, Distortion and Feedback — Nelson Pass / 2008

Audiophiles seem to revel in minor controversies – vinyl vs CD's, tubes versus solid state, capacitor, wires, magic dots... and negative feedback. At one extreme, the position is that “feedback makes amplifiers perfect”. At the other extreme, “feedback is a menacing succubus that sucks the life out of the music, leaving a dried husk, devoid of soul”. The former viewpoint usually belongs to so-called “objectivists” who have a fine appreciation for electronic theory and measurements. Their opposites would be the “subjectivists” who emphasize the listening experience and often own tube amplifiers. Accusations are occasionally made that objectivists can't hear, and… 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...