Brüel & Kjær

The Company

Brüel & Kjær (Sound and Vibration Measurement A/S) is a subsidiary of UK-based Spectris plc. Brüel & Kjær is manufacturer and supplier of sound and vibration solutions. The company headquarters is based in Nærum, Denmark. Brüel & Kjær has sales offices in 55 countries and more than 500 employees working within local sales, service, and support worldwide.

The Founders

Bruël & Kjær was founded by Per Vilhelm Brüel (Denmark, March 15, 1915) and Viggo Kjær (Denmark, June 5, 1914) on November 28, 1942.

The two men met while studying at the The Polytechnic School in Copenhagen (now The Technical University of Denmark). After receiving their M.S. degrees in 1939 they decided to start a company developing instruments for acoustic measurements.

Holger Nielsen joined the company as third partner, in 1945. He was with the company until his death in 1978.

Brüel & Kjær products

• 1940s – Various precision measurement instruments including radio frequency analysers and Geiger counters.The first Brüel & Kjær instrument produced was Type 2401, a vacuum tube voltmeter. The success of the company started with Type 2301 in 1949. Since then it has been updated a number of times. The latest version is Type 2307 was introduced in 1972. In 1943 Brüel & Kjær launched Type 4301 - the world's first Charge Accelerometer - and entered the world of vibration measurement.

• 1950s – focus on sound and vibration measurements, including development of logarithmic level recorders, signal generators and frequency analyzers.

• 1960s – Birth of the Brüel & Kjær range of measurement microphones, preamplifiers and calibrators. IEC standardised precision sound level meters were also introduced.

• 1970s – Development of parallel analyzers, including the world’s first analyzer to use digital filters.

• 1980s – Introduction of the first commercially available instrument for sound intensity measurement and the expansion of the range of instruments; for example, dual channel FFT analyzers.

• 1990s – Multichannel and multi-analysis systems, including acoustical holography array systems.

• 2000s – Surface microphones and new technologies such as TEDS, Dyn-X, REq-X, LAN-XI and much more.

Organisational developments

In 1992 Brüel & Kjær was sold to AGIV (a German holding company), and split into a number of separate companies:

• Brüel & Kjær Sound and Vibration Measurement A/S (the core sound and vibration market)

• Brüel & Kjær Vibro (machinery condition monitoring)

• B-K Medical (ultrasonic medical diagnostic instruments)

• Innova Air Tech Instruments A/S (gas analysis instrumentation)

• Danish Pro Audio (studio microphones)

After the division of the company, a number of former employees formed G.R.A.S. Sound and Vibration (measurement microphones). The sale and division resulted in most of the production and some research and development operations being outsourced. AGIV formed the Spectris Division, which included Brüel & Kjær, Hottinger Baldwin Messtechnik GmbH (HBM), and BTG Instruments GmbH. In July 2000, the Spectris Division was sold to Fairey Group Ltd. (a British Company), and in May 2001, Fairey Group changed its name to Spectirs Plc.

Most recently, Brüel & Kjær has acquired LDS Test & Measurement with effect from January 2009. Read article Brüel & Kjær overtager førende firma i vibrationsplatforme

Read more about Acoustical measurements and instrumentation