Pass Labs is a high end audio company based in Foresthill, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, USA founded by Nelson Pass

Nelson Pass

Nelson Pass is a noted and widely respected designer of audio amplifiers.Unlike some audio engineers, Pass remains vocal that listening tests remain valuable and that electrical measurements alone do not fully characterize the sound of an amplifier.Mr. Pass holds at least seven U.S...

, a well known figure in the high end audio community. Pass is known for unique and innovative, as well as practical, circuit designs.

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

Nakamichi

is an historic Japanese high end audio company most famous for its innovative and very high quality audio cassette decks.In 1972, Nakamichi launched its first Nakamichi-brand products, home audio gear that included the world's first three-head cassette deck...

.

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 MOSFET

MOSFET

The metal–oxide–semiconductor field-effect transistor is a transistor used for amplifying or switching electronic signals. The basic principle of this kind of transistor was first patented by Julius Edgar Lilienfeld in 1925...

s. The Aleph amplifiers had a unique appearance, a cube with heat sink

Heat sink

A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...

s 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

JFET

The junction gate field-effect transistor is the simplest type of field-effect transistor. It can be used as an electronically-controlled switch or as a voltage-controlled resistance. Electric charge flows through a semiconducting channel between "source" and "drain" terminals...

 input stage is to be added.

Today Pass Labs makes amplifiers, preamplifier and speakers. Pass Labs is also a supporter of the DIY audio

DIY audio

DIY Audio means "do it yourself" audio. Rather than buying a piece of possibly expensive audio equipment, such as a high-end audio amplifier or speaker, the person practicing DIY Audio will make it him/herself...

 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

Balanced audio

Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...

 signal circuit, and continue to receive critical acclaim. See U.S. Patent

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

number 5,376,899.

External links

• Pass Labs Web Site
• Threshold Web Site
• First Watt Web Site
• PassDIY Pass DIY web site.
• 1997 Aleph 3 Review 1997 Review of Pass Aleph 3 in Stereophile Magazine
• 2001 Aleph 30 Review Review of Volksamp Aleph 30.
• 2003 XA160 Review 2003 Review of Pass XA160 amplifier in Stereophile Magazine.
• 2005 XA160 Review 2005 Review of Pass Labs XA160 amplifier from Ultraaudio online magazine.
• 2004 First Watt F1 Review from Enjoythemusic.com Online Magazine
• 2005 First Watt F1 "Review" From Stereophile Magazine
• 2005 Review of First Watt F1 from Positive-feedback online magazine