"Concentric Dual" Loudspeaker

Originally released as the "Concentric Dual", but populary referred to as the "Monitor Black" this design was conceived around 1946 by Ronald Rackham. This 15" speaker was originally developed as a reference tool for measuring microphones, but was soon launched as a product in its own right. It was displayed at the 1947 Radio Olympia exhibition in the UK, and quickly gained credibility with the professional market (through orders from the GPO and the like).

This design remained as the basis for all Tannoy dual concentrics for about 30 years (up to and including the Monitor HPD of the late 1970's).

15" Monitor Black:

The chassis casting of the 15" Monitor Black differs from the design of the later models. The basket of the 15 " Monitor Black has four straight spokes from the outer ring back to the magnet assembly. The basket was finished in black "crinkle finish" enamel, and has a very substantial appearance.

12" Monitor Black:

The 12" Monitor Black was released after the 15" unit. There are production variataions in the baskets and paint for this model - some early units have pressed-steel baskets, painted all-over in black gloss enamel. Other units have a cast, silver-painted, chassis but retain a black-enamel painted magnet cover.

(See comparison at above-right: Monitor Black 15" [upper] versus Monitor Black 12" [lower] with cast chassis and a black magnet cover).

In 1949 the Tannoy 12" Dual Concentric loudspeaker was demonstrated to Decca, and they subsequently placed an order for 900 loudspeakers to be used in the Decola gramophone. Later, in 1950, Arthur Haddy, (Chief Recording Engineer at Decca) heard the Tannoy Dual Concentric, and ordered them for used at the Decca FFRR Studios. The loudspeakers were named the Monitor Silver.

The rapid industry recognition for the Dual Concentric continued when EMI ordered them for the Abbey Road recording studio in 1951.

See also, the lauch of the Dual Concentric at the London Radio Show, 1947
on the Tannoy web site (click thumbnail image at right).

(Some historical details above are sourced from www.tannoy.com)


 Above: Cross-Section of the 15" Dual Concentric Monitor Black.

  Above: Advertised Frequency Response of the 15" Dual Concentric Monitor Black.


Above: This early 12" Tannoy Monitor Black features a pressed-steel frame.
(Photo courtesy allofus@es.co.nz)


Above: The 12" Tannoy Monitor Black with crossover.
(Photo courtesy allofus@es.co.nz)


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