Product Details

A major loudspeaker invention

Throughout the history of broadcasting and recording, certain exceptional developments have become milstones in the progress of sound reproduction.

One such milestone was the world’s very first low distortion amplifier – the famous original Leak Point One, in 1945.

Another was the pioneering major breakthrough with the invention of the fantastically rigid Leak sandwich cone diaphragm – which was demonstrably of great strength and many times stiffer than all conventional forms of cone, of its time.

To understand the impact of this innovation, one must remember that to obtain low distortion, the movement of a loudspeaker diaphragm, or cone, should follow as accurately as possible the waveform of the signals applied to its voice coil.

The ability of the current to follow these impulses accurately depends upon the lightness and stiffness of the cone assembly.

Many conventional cones: paper, impregnated fabric, plastics, aluminium etc all generally suffer from low stiffness.

This results in significantly larger areas of the cone vibrating in motion, uncontrolled by the voice coil.

These uncontrolled emotions produce transit “hangover”, amplitude distortion (peaks and troughs in the frequency response) and intermodulation distortion (lack of clarity of spurious tones).

Those shortcomings are inherent in almost all direct radiator loudspeaker systems using conventional cones, irrespective of cost.


Axial pressure response of Sandwich 250 Loudspeaker


All of these shortcomings are overcome by the Leak Sandwich construction.

Originally presented in 1961, the Sandwich used engineering and design principles applied to airframe construction.

Now, reintroduced and re-engineered with modern-day learnings, the new Leak Sandwich cone comprises of a stiff aluminium skin for the outer surfaces (where the stresses are greatest) bonded to a thick core of a polymethacrylimide (PMI) based structural foam, often used aerospace and the automotive industries.

This applied, precision-engineered use of the most suitable materials in optimum proportions and dispositions gives immense rigidity.

This means the Leak Sandwich cone reproduces the signal applied to the voice coil, totally free from mechanical break-up and its associated distortions.

The result is a remarkably smooth frequency response, free from violent peaks or troughs over a very broad frequency range, indicative of an excellent, transient response.

It is not often sufficiently realised how profound the influence of the loudspeaker housing (the cabinet) is on the overall acoustic performance.

Its design requires a great degree of electroacoustic knowledge as a design of the motor units themselves.

The new Leak Sandwich cabinet benefits from 60 years of technological development since the original.

The structure consists of a composition of MDF and composite board, thus creating a second ‘sandwich’ reference, with the boards layered for optimum cabinet strength.

While the new cabinet fuses intelligent bracing with this ‘sandwich’ of materials, it also maintains a specific front-rear bracing, with the distinct, visible countersunk screw on the rear – a famous trait of the original.

With the Leak Sandwich 150 and 250, the high-frequency driver has been developed, incorporating a rear chamber damped to absorb the output from the back of the dome.

This innovation not only isolates the HF unit from the rest of the loudspeaker, it has the added benefit of reducing the resonant frequency of the treble unit.

Taking the resonant frequency below the crossover region means the audible spectrum of the bass, mid and high frequencies can be sewn together with an added dimension of detail and harmonics, eliminating the requirement to harshly adjust the definition of the high-frequencies.

And that very sewing is conducted by a crossover of the highest order, developed over thousands of hours of listening, not just simulation as is the tendency in modern loudspeaker design.

Such is the format of the Leak Sandwich 250, many traditional stands would not allow for sufficient presentation of this loudspeaker.

To address this consideration, the Sandwich 250 is complemented by a precision-measured plinth that positions the loudspeaker’s driver array at the optimum level and position.

The result is a finely finished loudspeaker and matching stand combination of furniture-grade quality, that eliminates any compromise of the listening experience for the proud owner.

LEAK Sandwich 250 Specifications

Model Sandwich 250
General description 3-way vented-box/standmount
Design philosophy and core technology
Enclosure type Bass reflex
Transducer complement 3-way
Bass driver 11"(280mm) Aluminium-Foamcore Sandwich cone
Midrange driver 4.25"(108mm) Aluminium-Foamcore Sandwich cone
Treble driver 1.2"(30mm) Coated Textile Dome
Full-range driver
AV shield No
Sensitivity (2.83V @ 1m) 88.5dB
Recommended amplifier power 25-250W
Peak power handling
Peak SPL 112dB
Nominalimpedance 6Ω (8Ω Compatible)
Minimumimpedance 4 Ω
Frequency response(+/-3dB) 42Hz - 26kHz
Bass extension(-6dB) 32Hz
Crossover frequency 470Hz & 3.1kHz
Cabinet Volume (in litres) 2.7L, 45.5L
Height (on plinth) 655mm
Width 370mm
Depth (with terminals) (300+30)mm
Carton size 500*430*790mm
Net weight 27.3kg/pcs
Gross weight 30.2kg/ctn
Finish Real Wood Veneer - Walnut
Standard accessories Rubber feet
Optional accessories Leak Sandwich 250 stand

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  • Product Type Unknown Type
  • Brand: Leak