The first of a series of notes - eventually to be gathered together on a page of their own - on early AC100 SDL trolleys with basket tops.

Some dimensions

The lower section of the trolley (the wheeled base unit). Both early on, and later, these were made of tubing with a diameter of 7/8". The early trolleys (with basket tops) were less broad, however, than later ones:

BASKET-TOP TROLLEY

Total width of whole - 29 1/4".

Inner width (between bars) - 27 1/2".

Total depth of base - 14 7/8".

LATER JMI TROLLEYS (and Thomas Organ Super Beatle trolleys). PARALLEL BARS ON TOP.

Total width of whole - 31 5/8".

Inner width (between bars) - 29 7/8".

Total depth of base - 15".

As the 4 x 12" cabinets were 27" wide, tolerances in the early trolleys were really tight - only 27 1/2" between the uprights.

Basket-top trolley (early 1965).

Castors

Kenrick Shepherd ball castors, 2" diameter, with screw thread - 5/16" British Standard Whitworth. For the time being, a quick picture of the base of one, the insert designed for Kenrick Shepherd ball castors with a threaded stem, 5/16", British Standard Whitworth. More to come soon.

Mounting hardware

Again, the format is different from the one later adopted by JMI for its standard AC100 trolleys. The handwheel face is engraved rather than pressed, the logo defined by bounding lines rather than fully recessed letters. This can also be seen in the photograph submitted by JMI to the Old Patent Office in October 1964.

Handwheel face, basket-top cab.

Detail from the photo of the AC100 SDL registered by JMI with the Old Patent Office in October 1964. The logo is "blued" out to indicate that the name was not part of the application. "VOX" had already been trademarked by Tom in the 1950s.

Handwheel inside face.

Forming part of the structure of the trolley frame is a sizeable hoop that locates over the "castle" style cabinet mount. Between the two, a brown phenolic ring (second photo below). The standard later JMI format can be seen on this page.

A circulat metal plate (not shown) goes between the trolley mount and the handwheel.

More to come on the early trolleys in a coming post.

Standard JMI AC100 SDL trolleys (from February 1965)

In contrast to early basket-top trolleys, later "standard" JMI trolleys were made out of 7/8" diameter tubing all round, the frame consisting of three (rather than two) sections that slotted together: the base (with wheels), and two side pieces that contained the locating points for the cabinet swivel mounts and half each of the top. These side pieces slotted into the base and into each other at top.

Early basket-top trolleys came in two sections: the base and a single section comprising of sides and top.

Detail of AC100 SDL serial number 392, mid 1965 (speakers dated May '65), parallel bars across the top of the trolley.

Below, a picture of an American Super Beatle trolley, wheels removed and part dismantled to show the three principal elements. In overall form, these trolleys were copies of JMI's AC100 SDL trolleys, though there are significant differences in detail.

American Super Beatle trolley to show the three main elements. JMI AC100 SDL trolleys had the same tri-partite form, and identical dimensions. Areas of difference: the type of castors used, the swivel mount, the intermediate bars on top; mode of production. The trolley pictured above was flown about the USA in the 1970s by "Consolidated Airlines" (transit labels still sellotaped on upper and lower sections).

The earliest dated instance of a new-style JMI trolley? - February 1965 in a short film clip shot at Dartford Road. The earliest instance currently known in terms of surviving amps? - AC100 serial number 236. More on the early black panel amps tomorrow.