W24 4.7 Ohm 14 Watt Wire Wound Resistor
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JMI designed a unique, four speaker open back enclosure to complement the power and response characteristics of the Vox UL760 amp head. The letters "G-R," stenciled in white paint on the inside of the enclosure, established that the UL760 cabinetry was produced for Vox under sub contract by Gla-Rev, a UK OEM woodworking firm based in Essex.
The UL760 enclosure was powered by two 12" 25 watt, 15 ohm Celestion T.1225 G12M "gray back" speakers and two 10" 15 watt, 15 ohm Celestion T.7721 (or in some cases T.7742) speakers. These speakers utillized a series/parallel wiring scheme that yielded a 15 ohm cabinet impedance. A 14 watt, 4.7 ohm wire wound resistor was wired in series with the 10" speakers to attenuate their output slightly.
The UL Series amps, including the 760, abandoned the use of XLR jacks and plugs for external speaker connection. The 760 head and speaker enclosure adopted standard 1/4" speaker jacks.
The outside dimensions of the UL760 cabinetry were 34" wide, 26" tall and 11.75" deep or ~38" wide, ~16" deep and ~31" tall when mounted to the swivel trolley. The top, bottom, sides and baffle board of the UL760 were made from 13 ply 3/4" baltic birch plywood. The upper and lower rear panels were 9 ply 1/2" baltic birch plywood. The 12" speakers were mounted 15" apart, center to center. The 10" speakers were mounted 18.5" apart, center to center.
The UL760 speaker enclosure was covered in traditional Vox black basketweave vinyl. The large injection molded vertical Vox logo had white, rather than gold, letters. The "two-pin" plastic corners and "pancake" feet installed on these cabinets were supplied to Vox by Rean of London.
Vox UL Series amplifiers were produced for just one year (1966) and in rather limited numbers. Very few original examples have escaped the ravages of time and the life on the road. |
