Build The Amazing FET Circlotron — Michael Rothacher / 2008

Cue the Theremin music! This article is about building your own all-FET Circlotron. It smashes atoms. No, strike that. It won’t smash atoms like a cyclotron, but it has a really cool name and it is, technically speaking, powered by atoms and very, very good at amplifying music. Alpha M. Wiggins of Electro-Voice is generally recognized as the inventor of the Circlotron amplifier although other inventors developed similar circuits around the same time period in the 1950’s. The Circlotron’s transformer-coupled vacuum tube output circuit, a floating bridge, was often drawn in a circular fashion; hence the name. Later, Circlotron-type output… More...

Pearl 2 — Wayne Colburn / 2010

Here is the long awaited sequel to the Pearl phono stage, named after my maternal Grandmother who was good with a sling shot , played piano and organ and occasionally listened to my early Hi-fi efforts if the smoke wasn't too bad. Pearl II addresses the major request received over the years - more gain for moving coil cartridges. Phono stage design is difficult to do well. Everything matters. Any low level phenomenon occurring in the parts of a phono stage shows up greatly amplified at the loudspeaker. This phono stage has about 55 dB gain at 1 Khz, and… More...