LEAK Sandwich

Harold Leak engaged Don Barlow, who had devised a way of making the cone of the loudspeaker from expanded polystyrene foam sandwiched between two sheets of aluminium foil.

A publicity photograph showed Harold Leak standing on top of one of his sandwich cones to demonstrate its exceptional rigidity.

The original Leak 'Sandwich' hi-fi speaker was a large two-way system employing a 330 mm (13 in) low frequency element, with the sandwich cone, cambric roll suspension, and cast aluminium chassis.

As was common at the time, the 75 mm (3 in) high frequency unit was a miniature version of the woofer, and was mounted onto the grille assembly, so fitted neatly into its own foam lined cavity on the face of the 60-litre (2.1 cu ft) bass enclosure.

Since transistorized amplifiers had become more common by this time, it was rated at a more contemporary 4 to 8 Ohms, with power handling of 18 watts.