Super-Symmetric Amplification — Nelson Pass / 1998

U.S. Patent # 5376899 describes a new amplifying circuit topology that takes advantage of the character of special matched balanced amplifiers that are cross-coupled to provide cancellation of distortion and noise. The result provides high performance with very simple linear circuits, better than previous efforts by an order of magnitude. We have dubbed the approach Super-Symmetry (Su-Sy), an homage to particle physics. Super-Symmetry works by exploiting the complementary characteristics of precision matched balanced circuits to differentially reject distortion and noise, and extends this symmetry to make the distortion and noise virtually identical on each half of a balanced amplifying circuit.… More...

The Kleinhorn Part 1 — Nelson Pass / 2004

33 years ago I decided to build a big horn system. Constructed in the dorm library over Christmas break, the result was dubbed The Claw, a straight exponential horn 9 feet long with a 42 Hz expansion curve and a 50 sq ft mouth. We mounted a JBL LE15A woofer in the throat and used a JBL 375 compression driver and horn for about 500 Hz on up. No matter where we pointed it, the cops showed up every time. I've always wanted to build a stereo pair capable of even lower frequencies, and these days I am fortunate enough… More...