Assembly of Jennings organs at 115 Dartford Road

1958 - 1960

Thanks to Len, some info on the speakers normally provided with the "Model G" organ in the late 1950s - Len was responsible for the final assembly of the organs - across the Jennings range - at Dartford Road from 1959 into 1960, having joined the department in 1958.

Detail from the "Model G" brochure, c. 1959.

The bass speaker cabinet was around 6 feet tall, 4 feet wide, and 2 feet deep. Inside, there was a centre partition. The bass driver was positioned at the top of enclosure facing downwards, driving the sound to the foot of the cabinet and out through ports.

The wedge-shaped enclosures were normally fitted with a 12" Rola Celestion. Four such cabinets were conventionally installed with the Model G.

The diamond-shaped enclosures contained 8" oval speakers - principally for reproduction of the trumpet militaire. As in the case of the 12" enclosures, four units were normally installed with the Model G, though as many as eight were sometimes required (and provided).

In large churches, a colossal amount of wiring will have been needed to link the speaker arrays to the organ's power amplifiers.

Derek Underdown's schema of the speaker wiring for the "Model G", dated 26th February, 1959. The diamond-shaped enclosures appear to contain two 3 ohm speakers. Thanks to Steve for the picture.

More to come (thanks to Len) on the assembly of organs at Dartford Road, c. 1958 to 1961.

Assembly of organs at Dartford Road, c. 1958 to 1960. The cable forms, voicing assembly sound generators, amplifiers and power supplies, were put together by three ladies: Sheila, Janice and Celia. Once complete, the assemblies were then soak-tested for 24 hours at one end of the shed.

When the time came for the build, Charlie, the department's woodworker, would make frames and sort out any difficulties that arose in the cabinets produced for JMI by its external contractor (possibly Glock in Crayford). Dave Grant and Len Player then tackled final assembly (which would normally take a couple of days), mounting the various elements in the cabinet, wiring up the sections, and testing the organ's functionality - voicings, tuning, and so on.

The length of time required to complete an organ - start to finish - naturally varied according to the model of organ in view. Smaller ones took around six to eight weeks - "lead time" from the point at which the order came in. Larger ones, the "Model G" in particular, which required sets of ancillary speaker cabinets, could take as much as three months.

Thanks to Len for the details. Below, a picture taken in the organ section at Dartford Road, probably in 1957, a year before Len joined the company - the key contact assembly of a Model B "Entertainment" organ.

Detail of a Jennings "Model B" organ during assembly, late 1957 / early 1958. Photo: Toni Standing, Derek Underdown's daughter.

A small but significant change to the assembly of organs in 1958: the move from multi-core cables to single core wire for internal connections in the larger organs (the Model G in particular). This had two main benefits - versatility and material cost. However, there was one drawback. Single core wire tended to break more readily when an organ was moved.

Interior of a Jennings organ - probably a Model G - photographed late 1957 / early 1958: twisted power cables, and loomed multi-core and single core.

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