LEAK Sandwich 250 Loudspeaker - Walnut

Is the LEAK Sandwich 250 the right floorstander for your system and room?

Where does the Sandwich 250 sit within the LEAK range and who is it for?

The LEAK Sandwich 250 is the flagship floorstanding loudspeaker in the current Sandwich series, which spans three models — the Sandwich 100, 150, and 250. Buyers who want the full three-way Aluminium-Foamcore Sandwich cone architecture in a full-range floorstanding cabinet choose the 250 over the Sandwich 150, which uses a smaller driver complement and cabinet volume. The Sandwich 100 is a standmount. The 250 is intended for the discerning audiophile who wants the Sandwich cone technology applied at its most complete implementation, with the added bass extension and dynamic headroom that a large reflex-loaded enclosure provides. Its 42Hz to 26kHz frequency response and 32Hz bass extension at -6dB position it for use in medium to large listening rooms where a standmount or smaller floorstander would lose low-frequency authority. Buyers who are building or upgrading a high-fidelity stereo system around LEAK's Stereo 130 or Stereo 230 integrated amplifiers will find the Sandwich 250 a natural pairing within the same design family, both visually and electrically.

What amplifier does the LEAK Sandwich 250 require?

The LEAK Sandwich 250 is rated for amplifiers delivering between 25W and 250W, with a nominal impedance of 6Ω and a minimum impedance of 4Ω. The 6Ω nominal rating means it's compatible with amplifiers specified for 8Ω loads, though buyers should confirm their amplifier is stable at 4Ω given the minimum impedance dip. Its 88.5dB sensitivity at 2.83V/1m means it doesn't need unusually high power to reach useful listening levels, but the 25W lower threshold means amplifiers below that rating aren't recommended. The 250W upper handling gives the speaker considerable headroom with powerful solid-state designs, and a peak SPL of 112dB suggests it can handle dynamic peaks without compression in typical domestic spaces.

What makes the Sandwich cone different from a conventional driver cone?

The LEAK Sandwich 250 uses a driver cone construction derived from aerospace engineering principles first applied to loudspeakers by LEAK in 1961. Conventional cone materials — paper, impregnated fabric, plastics, and aluminium — share a common limitation: they flex under the rapid changes in signal applied by the voice coil. When a cone flexes rather than moving as a rigid piston, areas beyond the voice coil move independently of the electrical signal. This produces transient hangover, amplitude distortion visible as peaks and troughs in the frequency response, and intermodulation distortion that blurs tonal clarity. The Aluminium-Foamcore Sandwich cone addresses this directly. Its outer skins are formed from aluminium, where bending stresses are greatest, bonded to a thick core of polymethacrylimide-based structural foam — a material also used in aerospace and automotive structures. The result is a diaphragm of immense stiffness relative to its mass. Because the cone moves as a controlled unit governed by the voice coil rather than breaking up into partial resonances, the frequency response remains smooth across a broad range without the violent peaks associated with conventional cone break-up.

How is the three-way driver array configured in the 250?

The LEAK Sandwich 250 is a three-way design using an 11-inch (280mm) Aluminium-Foamcore Sandwich bass driver, a 4.25-inch (108mm) Aluminium-Foamcore Sandwich midrange driver, and a 1.2-inch (30mm) coated textile dome tweeter. The crossover transitions occur at 470Hz and 3.1kHz, dividing the audible range so that each driver operates within the frequency band it's sized to handle. The bass driver manages low-frequency reproduction down to the cabinet's tuned bass reflex output, the midrange handles the critical vocal and instrumental range, and the coated textile dome covers the upper frequencies through to 26kHz. Using the Sandwich cone construction in both the bass and midrange drivers means the distortion mechanisms associated with conventional cone break-up are controlled across the majority of the frequency range, not just at one frequency extreme. The bass reflex enclosure is tuned to extend low-frequency output, contributing to the 32Hz bass extension figure.

What is the purpose of the rear chamber on the tweeter, and how does it affect crossover integration?

The LEAK Sandwich 250 incorporates a rear chamber behind the 30mm coated textile dome tweeter, specifically damped to absorb the output radiating from the back of the dome. This acoustically isolates the high-frequency unit from the internal environment of the loudspeaker cabinet, preventing back-wave energy from colouring the dome's output. The damped rear chamber also lowers the resonant frequency of the tweeter itself, bringing it below the 3.1kHz crossover point. With the tweeter's resonance sitting below the handover frequency, the crossover network can blend the midrange and high-frequency outputs without the steep correction filters that would otherwise be needed to manage a tweeter resonance within or near the crossover region. The crossover itself was developed through extended listening sessions rather than simulation alone — a distinction relevant to buyers evaluating how the frequency bands integrate in practice rather than purely on paper.

Does the Sandwich 250 require a dedicated stand?

The LEAK Sandwich 250 is a floorstanding loudspeaker that doesn't require a stand for operation, but LEAK offers the Sandwich 250 Stand as a separately available accessory. The format and height of the 250's cabinet mean standard aftermarket stands don't position the driver array at the correct listening height, which can affect stereo imaging and frequency balance at the listening position. Buyers who intend to use a stand should consider the dedicated option, which positions the driver array at the geometry determined during development and is finished to match the cabinet.

How is the Sandwich 250 cabinet constructed to control internal resonance?

The LEAK Sandwich 250 cabinet is built from a layered composition of MDF and composite board, bonded in a sandwich configuration to maximise structural rigidity. Internal bracing runs front to rear, and a visible countersunk screw on the rear panel is retained from the original 1960s Sandwich design as part of that front-rear bracing arrangement. The dual-material layered cabinet limits the resonance and flexing that can add colouration to driver output. Cabinet volume is specified across two separate chambers — 2.7 litres and 45.5 litres — consistent with the separate loading requirements of the midrange and bass sections of the three-way enclosure.

What does the 'handed' driver layout mean for stereo installation?

The LEAK Sandwich 250 is supplied as a matched pair with a handed array configuration, meaning the driver layout is mirrored between the left and right cabinet. The positioning of each driver is arranged so that when both speakers are placed symmetrically in a stereo setup, the spatial relationship between the midrange and tweeter is consistent across both channels, enabling the precise stereo soundstage projection the layout is designed to achieve. Buyers should position the speakers with the correct channel assignment to preserve this arrangement.

How does the Sandwich 250 present in a listening room?

The LEAK Sandwich 250 in Walnut is finished in a real-wood veneer rather than a vinyl wrap or painted surface. The aluminium trim inserts on the cabinet are matched and finished to the same standard as the driver trims and cone materials, creating visual continuity between the acoustic components and the cabinet finish. The decorative grille cloth is specified for acoustic transparency, so it can be used without affecting the frequency response at the listening position.