By late 1964, the single speaker AC15 had more or less been phased out, at least where official JMI pricelists were concerned. The model exported to the USA was the Twin and probably exclusively with NORMAL voicing. No provision for the Bass variant is made in Thomas documentation.

Neither the AC15 nor AC30 sold particularly well in the USA, and it was not long before Thomas set about producing (with JMI's consent) its own range of amplifiers, smaller valve models first (to replace the AC4, AC10, and AC15), then solid state. English-made amplifiers were gradually evicted from its catalogues.

The last major order placed with JMI by Thomas came in the summer of 1966 and is likely to have consisted largely of spare parts - cabinets, components, fittings and so on. These were held in stock in the Thomas Service Centers through to 1969 and beyond.

Below, a selection of Thomas documents relating to the AC15 from late 1964 through to 1967.

December 1964. Fuses were a particular concern due (a) to the differences in wall voltage in the two countries (UK and the USA); and (b) to the ways in which fuses were rated. English fuses blew at the rated current; American AG fuses went a good way beyond.

1967: circuit diagram, redrawn by Thomas Organ.

1967: parts list.

On to the Thomas Organ AC15 parts document from 1969.

A selection of material relevant to the AC15 in the 1950s and early 1960s is being gathered together here.