The Model "G" was the one of the largest units produced by Jennings. Its dimenssions, as given in December 1958, and January and December 1959, were: - 5 feet and 1 inch tall; 7 feet wide; 5 feet deep. Power output - 150 watts: "Sound distribution is through three separate channels, totalling 150 watts" - in other words, three power sections of 50 watts each. These were designed by Derek Underdown. A section on speakers can be found at the foot of this page.

Further pages on Jennings organs can be found here. Other years will follow soon. A sequence of pages on guitar amplifiers, beginning with 1957, starts here.

The Jennings Organ Company Model G

Below, some material relating to the Jennings Organ Company's demonstration of the "Model G" organ - an enormous three manual unit - at the church of St James, Kidbrooke Park, near Blackheath, South London, on 4th December 1958. (1) Derek Underdown's photo of the installation; (2) an advert in "Musical Opinion" magazine, November '58; and (3) a brochure for the "Model G", based on the initial publicity, from late 1960 or early 1961 - the price of the organ rose from 1850 guineas to 1975 guineas around December '60.

1958 was the year of the big sales push for the "Model G" - further material on this page. Of note was the shipping of a "Model G" to New Zealand, installed by JMI engineers in the Civic Auditorium, Lower Hutt.

The organ contained three 50 watt amplifiers designed by Derek Underdown - 150 watts in total! - which could be set up to drive external speakers, wall or floor mounted.

Derek Underdown's photo, thanks to Toni Standing, his daughter.

November 1958.

"Musical Opinion" magazine, January 1959.

Music trade press, November 1959.

Above, a JMI advert placed in a music trade journal, November 1959 - Model A, C, D1, D2, DS, H, and G organs. At the foot of the page a note that the company's organs were on display in the basement of the shop at 100 Charing Cross Road (this by September 1959). The basement had been the Jennings "London Accordion Centre" from 1956. The only organ not displayed was the gargantuan Model G as it was too large for the stairs down.

"Musical Opinion" magazine, December, 1959. Model G.

Speakers

Below, a detail from the flyer illustrated above, late 1960 / early 1961. Nine speakers were recommended for the organ, which could put out 150 watts. The bass enclosure (lower roundel, at right) probably contained a Goodmans Audiom 90, an 18" driver developed in the early 1950s for organ and public address applications. The middle frequency wall-mounted units possibly something like the Goodmans Audiom 60; the wall-mounted tweeters perhaps embodying a pair each of Goodmans Trebax horns?

The "nine loudspeakers altogether" mentioned in the brochure will therefore have been: 1 x 18"; 2 x 12"; and 6 x Trebax tweeters.

The system will have had a fairly complex cross-over network to protect both tweeter and wall-mounted middle-frequency units from excessive power, and to protect the horns especially from damaging low frequencies.

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Documents relating to Jennings (Vox) guitar amplifiers, 1957