In July a new "Stereophonic" series of Vox amplifiers was announced by JMI in the British Music Trade press, July 1961. This was in fact a reference to the "Top Boost" units fitted to AC30 Super Twins (with closed-back "pressurised" speaker cabinets).

Music trade magazine, July 1961.

The comment "Production at the moment is in hundreds, and thousands are being prepared for a large order received from abroad" is intriguing. Perhaps Germany? Given the date - July 1961 - it is probable that some of the amplifier sections in view will have had black control panels, others very early copper.

Serial number 5329 amplifier section, the top boost unit added (as is normal) in a cut-out in the back panel.

The circuit diagram was drawn out by John Bell on 11th December 1961. A copy can be found on this page.

Below, a further mention of the "stereophonic" Top Boost circuit from a Jennings flyer, late 1961:

Paragraph from a Jennings flyer, late 1961 - the text as a whole is below.

The image accompanying the text above.

On to the next page: the Vox Top Boost circuit.