Pass Labs

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Aleph 3 Amplifier

Pass Labs is a high end audio company based in Foresthill, California, USA founded by Mr. Nelson Pass, a well known figure in the high end audio community. Mr. Pass is known for unique and innovative, as well as practical, circuit designs.

Pass worked at audio company Threshold, where he developed the "Stasis" series of amplifiers. These designs were later licensed to Nakamichi.

The Pass labs Aleph series of amplifiers were highly regarded at the time they were introduced. These amplifiers operated pure "Class A" and contained very simple internal circuitry using MOSFETs. The Aleph amplifiers had a unique appearance, a cube with heat sinks on all four sides, a very practical solution to the high amounts of heat generated by the Class A design.

After the Aleph series of amplifiers was discontinued, a separate entity "Volksamp" was licensed to continue to produce a similar product. Aleph 30 and 60 Amplifiers were made by Volksamp until production ceased in 2003.

Currently, manufacture of the Aleph series of amplifiers is to be continued by First Watt, a self described "kitchen table" amplifier company founded by Nelson Pass in 2004. First Watt initially produced power trans-conductance amplifiers (or technically a power current source). Reference: F1, F2 These current domain amplifiers are only suitable for use with certain unique types of speakers. With respect to the Aleph amplifier line, First Watt has announced plans for the Aleph J, a revision of the famous Pass Labs Aleph 3/ Volksamp Aleph 30 wherein a new JFET input stage is to be added.

Today Pass Labs makes amplifiers, preamplifier and speakers. Pass Labs is also a supporter of the DIY audio community and maintains a separate internet presence for this purpose (see external links).

Current Pass Labs "X" series amplifiers use a distortion canceling balanced audio signal circuit, and continue to receive critical acclaim. See U.S. Patent number 5,376,899.