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2000 Ohm headphones. The set was developed in the twenties and was still being made in the fifties.
Sidney George Brown, the company founder, was a prolific inventor of electromechanical devices, including the "Microphone Amplifier" (1921) which permitted loudspeaker operation from a crystal set without the use of valves, and a gyro compass. He set up a business in Watford (North of London) in the year 1910 and later had a works in North Acton, London W3. The company eventually became part of the Racal organisation which in turn became part of Thales-Racal Acoustics.
Made in: 1950
Purchased in: 2006
Sold in: 2023
DC resistance: 2000 Ohms
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A one sided earphone with a handle and a volume control knob in the bottom.

Sidney George Brown the company founder was a prolific inventor of electromechanical devices, including the "Microphone Amplifier" (1921) which permitted loudspeaker operation from a crystal set without the use of valves and a gyro compass. He set up a business in Watford (North of London) in the year 1910 and later had a works in North Acton, London W3. The company eventually became part of the Racal organisation which in turn became part of Thales-Racal Acoustics.

Made in: 1925
Purchased in: 2006
DC resistance: 2000 Ohms
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Made in: 1924-1925
Purchased in: 2011
DC resistance: 2000 Ohms
 
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Advertisement in Popular Wireless Weekly, August 18, 1923

 

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Made in: 1923
Purchased in: 2005
Sold in: 2023
DC resistance: 2000 Ohms
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Advertisement in Wireless Weelky, December 24, 1924

 
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Made in: 1925
Purchased in: 2009
DC resistance: 4000 Ohms
Price (in The Netherlands) f 11,-
Advertisement in Radio-Expres, May 1, 1925

 
Label on the box of the earphone
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Made in: 1925
Purchased in: 2017
DC resistance: 2000 Ohms
 

Data
Made in: 1924
Purchased in: 2019
DC resistance: 4000 Ohms
Advertisement from 1924

This page was last edited on 02.03.2023