Zen Variations 5 Low Res — Nelson Pass / 2003

The Zen Amp concept is an exploration of how well you can make a simple audio amplifier perform. It makes for an interesting illustration of design technique, since more complex circuits are inevitably composed of collections of simple circuits, and it is well recognized that the optimization of these simple sub circuits is usually the key to getting the most out of the larger circuit. Apart from that, there is aesthetic pleasure in rendering a device in a simple way. Also we find that, other things being roughly equal, simple circuits sound better musically. The Zen series has so far… More...

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...