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...

Current Source Amplifiers and Sensitive Full Range Drivers — Nelson Pass / 2004

Conventional wisdom holds that a pure voltage source amplifier is ideal for audio applications, and generally designers of loudspeakers work to that assumption. This belief has particularly been dominant since the development of high power solid-state amplifiers that began in the 1960’s. A small minority of audiophiles thinks otherwise, and these are often people using low wattage tube amplifiers with unusual looking speakers. Well, of course entertainment is full of fringe elements. A couple of years ago, Kent English and I were playing around with various ribbon tweeters, noting how the ribbons themselves seemed perfectly happy being driven by a… More...