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...

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...