Jennings Electronic Industries O50 (Organ 50)
Solid state, 40-50W, mid 1969 to mid 1973
Detail from the newspaper-format catalogue produced for the Russell Hotel Trade Fair, August 1969.
In August 1969 Tom Jennings expanded his range of small-format lightweight solid state amplifier sections with the official release of the 050 (for organ) and B50 (for bass). These joined the O100, B100, and PA100, which had been first in line. The page on the Jennings B100 can be found here, and one on the 0100 here.
Pictures taken at the Frankfurt Trade Fair in late February 1969 tend to indicate, however, that development of the two smaller amplifiers was largely complete by that point. It is difficult to tell for certain though. By mid 1969, the B50, B100, O50 and O100 all took the same form, the only distinguishing feature externally being the name of the model on the fascia, top right.
A detail of a picture taken at the Frankfurt Musikmesse, late February 1969, two new-style amplifiers right of centre. Resolution is not quite good enough to tell definitively whether these are the new O50 and B50, or simply a new version of the B100.
A brief preview of the Russell Hotel Trade Fair of August 1969 speaks of Jennings amplifiers with a "flat response". These were in fact the O50 and O100, described by Jennings in the catalogue of 1969 (extract at the head of this page) as having an "even response".
Detail from a preview report, printed July 1969.
The slight mis-wording, suggesting the amps with the "flat" response were something other than the organ amplifiers, was corrected in the preview of the Fair of August 1971::
Detail from a preview report, printed August 1971.
The six amplifiers in the range - O50, O100, B50, B100, PA50 and PA100 - all had preamp output and power amp input sockets, providing an unusual degree of versatility for their relative positions in the market. For an overview of the JEI "O" and "B" series amps, see this page.
Below, an O50 modified for Robert Valentine by Dick Denney to provide more treble:
Robert's O50, modified by Dick Denney. Robert worked for JMI from late 1959 to 1964.
As mentioned on other pages, Tom's range of solid state amps was largely modular. The 050's power section was identical to the one used in the B50 and in the PA50. From an electronic standpoint, only the preamps were different.
Although no documentation relating to the design process has come to light so far, it is likely that the range was the work of Dick Denney and John Oram, probably in association with Triumph Electronics. The arrangement of the back panels of the Jennings "B" and "O" amplifiers is identical to that of certain solid state - "Silicon" - amps that Triumph marketed under its own and Rosetti's name - pictures here.
The 1970s
So far as one can judge, sales of the 050 were reasonably good in the early 1970s. The amp remained in the Jennings catalogue until mid 1973, at which point it was deleted, along with its fellows, the B50, B100, O100, and old-style PA50 and PA100s. The Jennings range was revamped with new designs and a striking new purple livery.
"Beat Instrumental" magazine, February 1970.
Jennings pricelist, December 1972.
Brief list of prices published in June 1973.
Surviving amps
Serial numbers probably began at 300. The lowest known at present is 306 (early 1970) and the highest 352 (mid 1971). Details of the former can be seen on this page and of the latter here.
Jennings did a good deal of trade with Europe in the early 1970s, and some really immaculate O50s survive in Germany and the Netherlands. It may be possible to obtain further pictures showing serial numbers in due course.
Below, an O50 complete with original cover:
