Trouble Shooting — Kent English / 2002

Pre-Amplifiers Within the Pass Labs pre-amplifier family we typically see two installation errors, both involving cable issues. The most common error concerns improper sequence of cable connection for our pre-amplifiers with dedicated outboard power supplies. The last cable attached to these preamplifier products must always be the power cord. Attach these cables out of sequence and the logic circuitry in these particular products may cause them to self protect. The power cord must be plugged into the power supply chassis after all other cables are attached and lastly plugged into mains power. If you have done this out of sequence,… More...

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...