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...

Build a MOSFET Citation 12 — Nelson Pass / 1981

Audio Amateur has published a number of projects modifying popular kits, usually Dynaco's. Obviously it is much less expensive to use the chassis and power supply, pots, connectors, switches, PC boards, and heat sinks that can be had for the price of a kit than to buy the components individually or have them made. Creating a one-off copy commercially typically costs as much as making 10 copies of the same item, because the dominant costs are design and set-up time which do not increase with quantity. Small wonder then that most technicians and designers who write for this and similar… More...