The Vox Gyrotone II rotary speaker cabinet (1967-1973)
Two speeds (slow and fast). One rotating 12" speaker, two static
Detail from the JMI catalogue of Spring 1967, the Gyrotone II on the left.
Click to enlarge. April 1967 pricelist. Standard production models.
JMI's plan initially was to produce only two models - the Gyrotone I, with a single speaker handling 25 watts; and the Gyrotone II, two speeds (slow and fast), handling around 65 watts - see this page.
By April 1967, the range had been expanded to encompass four models, though the vast and supremely heavy Gyrotone IV did not last long, probably disappearing from the catalogue by late 1967.
Gyrotones were principally designed for use with organs - the Gyrotone II for medium-sized halls, clubs, and the studio. Its effect was described as "Chorale". Guitarists were already experimenting with speaker effects at much the same time as the Gyrotones appeared - a tendency that increased further as the late 1960s wore on.
In terms of competition, there were various types of Leslie unit and one from Selmer, the latter effectively a Leslie marketed from 1967 to 1968 in a Selmer-designed cabinet, but it evidently did not sell well. The Selmer unit is slightly different though from JMI's units, having a built-in amplifier at base. The Gyrotone II is perhaps closest in overall conception to the Leslie 201 of the early 1960s, which has a similar complement of fixed and rotating drivers.
To judge from survivals, JMI sold around at least 122 Gyrotone IIs, and probably a good number more. As in the case of the Gyrotone I, covers were provided.
Detail from a JMI brochure for Italy, early 1968. "The Vox Girotone in three versions. It's the Leslie of 1968".
Detail from a VSEL brochure produced for the German market in 1969. Goodmans speakers are now standard.
Detail from the VSEL pricelist for the UK, February 1969. £125 was a substantial amount.
In 1969, "Vox Sound Equipment Limited" (1968-1969) devised a simplified cabinet - almost a cube in form. Wheels were built into the bottom and plastic handles were let into the back panel. Speakers were generally Goodmans at this point rather than Celestions. "Vox Sound Limited" continued to produce units until late 1972. Offshoots of the Gyrotone II were the "Riviera-Gyrotone", designed for and supplied with Riviera organs (introduced in early 1969); and the "Gyrotone 50" of 1970, incorporating a 50W Midas amplifier.
Detail from the "Vox Sound Limited" catalogue of late summer 1970. The Gyrotone II now in near cube format.
A detail from the pricelist that accompanied the catalogue above. Note that covers are extra.
In late 1969, a version of the JMI Gyrotone II was brought to market by "Jennings Electronic Industries", Tom Jennings's new company. The format was the same (split front with a sloping upper section), but the cabinet was normally fitted with JEI grille cloth. Presumably JEI either acquired cabinets from VSEL when it went over to the new cube format, or bought new from the original cabinet maker - very probably Henry Glass (Gla-Rev) in this instance.
Key aspects of the Gyrotone II
JMI and early VSEL cabinets have split fronts, both sections covered with cloth (unlike the Gyrotone I), the upper sloping. On the front panel, the power lamp nestles in the "O" of "VOX". Cabinet construction is complex: inset lattices covered with grille cloth in the sides and front to allow sound to disperse in a three-dimensional way. Back panels are normally solid but with a small cutaway along their lower edge (to de-pressurise the cabinet). Just under half-way down on the sides there are metal carrying handles.
Inside the cabinet, a slider board, the rotating fan and motor on top, a 12" Celestion T1297 speaker fixed to its underside in a wooden compartment. Two "static" Celestion T1297s in the front of the cabinet facing forwards. Celestions were later superceded by Goodmans speakers.
Low down on the back panel: the mains socket; fuse; jack socket for the input signal from the amplifier or organ selected to drive the cabinet; and footswitch connection.
A two-button footswitch was provided - one switch to turn the rotating speaker on or off, the other to toggle between fast and slow rotation.
Surviving Gyrotone II units
JMI serial no. 5122
Excellent condition. A video of the unit in action below. Note that the "Model" panel on the serial number plate is stamped "2".
VSEL serial unknown
The new near cube format. Note the speakers with "Vox Sound Equipment Limited" labels. The footswitch to control the speed has been replaced with a toggle switch block.
VSL serial number 047
Probably issued with a Continental organ
Two sets of photos combined. "Vox Sound Limited" serial number 047: "CONGYRO2". "Vox Sound Equipment Limited" labels on the Goodmans drivers. Silver string around the cabinet.
VSL serial number 061
VSL serial number unknown
This unit, though relatively late, appears to have a JMI serial number plate. Speakers are Celestion greenbacks - perhaps T1925s, which were regularly used by VSL in its "general purpose" speaker cabinets.
VSL Riviera Gyrotone, serial number 5055
"Vox Sound Equipment Limited" speaker labels, but a "Vox Sound Limited" serial number plate.