Current Source Crossover Filters — Nelson Pass / 2004

In today’s marketplace, audio power amplifiers are conventionally viewed as voltage sources, delivering a given voltage at the output that is a multiple of an input voltage. To the extent that they are truly voltage sources, having a very low output impedance, they simply deliver whatever current happens to reflect the response of the loudspeaker to the defined output voltage. Recently I have been playing with current source power amplifiers that have high output impedances and deliver a specific current to the load in response to an input voltage. The voltage across the loudspeaker reflects its response to this defined… More...

Burning Amplifier # 1 — Nelson Pass / 2009

The Burning Amp Festival is an event every October in San Francisco. Do-it-yourself audio enthusiasts from all over gather to show off their projects, listen to talks and equipment demos, and rub shoulders with the rich and famous. Having a very large collection of audio parts and diminishing storage space, I seem to have fallen into the role of Santa Claus there, distributing components and cheap advice, with white hair, beard and a large elf (Colin Pass) to add verisimilitude. This year we also brought a batch of unfinished amplifiers, consisting of a chassis, connectors, transformer, power supply capacitors and… More...