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Vox UL4120 and UL7120 cabs

Roger Waters

Click on the thumbnails below for larger versions of the image.


A huge amount of effort was put into the production of these cabs, both by GlaRev, the company that made and tolexed the cabinets, and by the finishers at the Vox/Burndept factory in Erith, who fitted among other things the speakers, and wired them up.

The drivers were Celestion T1225s, effectively a standard T1221 ceramic G12H 55hz (bass resonance) unit, sprayed silver for Vox. The power rating was (an optimistic) 30W apiece.

Attention to detail was such that even in closed-back cabs, the "VOX" labels on the Celestions were always horizontal, in spite of the varying orientation of the terminals: the labels were evidently applied after the speakers had been fitted.

The wiring in particular is a work of art. The schematic below, drawn up on the basis of surviving cabs, shows how involved it was.

Ignore the fact that one wire is in represented in red. This schematic was also followed in a small number of AC100 cabs made in 1966, though the runs of wiring in those are naturally differently arranged.

The total impedance of the cabs was 15ohms, meaning that they could later be used with Vox solid state amps, as they regularly were.

An intital fear was, however, that the four Celestions would not stand up to the power of the 4120 and 7120 amps. Perhaps the experience of the tour in Germany in Spring 1966 was one of the reasons why The Beatles had a spare cab for the Manila concert in June of that year (pictured in transit at Hong Kong airport). Closed-backs gave more protection to the drivers perhaps, but even so, many of the Celestion T1225s and midaxes seem to have gone.

Two surviving closed-back cabs illustrated below have outline "templates" for speakers in place of the horns. It has been suggested that the drivers were envisaged as being 10" units, but the size of the outline is actually more in line with 12" - a 6x12". But no cab has so far come to light in this format.

Vox UL4120 cabs - closed-backed

A closed back 4120 cab formerly belonging to keyboardist Manuel Fernández (Manolo) of Los Bravos. Left, Manolo with the cab on end and his Supreme. Centre, cab and amp advertised on a Spanish auction site in the mid 2000s. Right, the cab (lower of the two) in England with another closed back and 4120 serial no. 221 on top.

Left, the interior of Manolo's cab - original speakers and horns replaced. Right, the other cab, with replacement Philips alnico speakers (rated at 15W apiece), the horn openings closed off.

The two cabs in the the picture further up this page are now in Austria, with 7120s and trolleys to accompany.

Cab formerly belonging to Rod Argent of the Zombies, who used it with his keyboard amp. Currently in the UK. Original speakers gone, but the midax horns and most of the wiring loom remains. The trolley is the first reproduction made by North Coast Music. On the baffle, note the template outline for 12" speakers instead of horns


Currently in the USA, acquired from Germany. Condition good. Original speakers in place and most of the wiring loom (though sections have been removed).

Vox UL7120 cabs - open-backed

Formerly in Germany, one now in the UK, one in the US. Cabs no. 6 and 9 (numbers chalked inside). Used for years in a theatre in Berlin. Stripped of original vinyl, backboards recovered in elephant tolex, the front grille cloth replaced with black. Original speakers - Celestion T1225s - and fittings survive. One set of speakers has date codes for April and May 1966, the other June 1966. Three of the four from the earlier set needed reconing. The midax horns were blown.

Cab no. 6.

Cab no. 9.

Left, unpacked after arrival in the UK. Right, the front with speakers and horns out.

Speakers before refurbing by Wembley Loudspeakers. Date codes are 21DL, 22DL, and 05EL = 21st and 22nd April 1966 and 5th May.

Left, a shot with the baffle out, capturing the "9"s. Centre, recovered, baffle back in. Right, the wiring loom in.

Fully functioning cab - a Celestion Creamback standing in for one of the T1225s, which was being refurbed.

Further pics to follow