Supravox Baffle-Compensé
Natural reproduction with substance.
A cabinet designed for the Supravox 285-EXC.
The Supravox 285-EXC is a high-efficiency 28.5 cm driver for bass and lower-midrange reproduction, known for its exceptional immediacy and directness.
To prevent these qualities from being obscured by cabinet resonances or typical “box sound,” it requires a concept that prioritizes control over effect.
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Concept
The Supravox 285-EXC (mk2) is not a typical “hi-fi woofer,” but a high-efficiency bass and lower-midrange driver with a field-coil motor.
The magnetic field strength is adjustable and directly influences efficiency and behavior — making the driver versatile, but only truly controlled if the enclosure does not interfere.
For this reason, LMH deliberately avoids standard bass reflex approaches and instead employs a baffle compensé / RJ-Wedge principle.
The driver operates against a defined, heavily damped rear volume that dissipates energy in a controlled manner and minimizes cabinet resonances.
This concept is historically known as the Supravox mounting method (“RJ Wedge Cabinets”) and is valued for its open, fast presentation without the typical “box sound.”
The objective is not maximum low-frequency extension on paper, but a foundation with structure:
supportive, fast, and clean in the lower midrange — serving either as the basis for purist setups or as a bass / lower-midrange partner to a horn or high-frequency system.
Manufacturing & materials
Manufacturing takes place entirely in the LMH manufactory:
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CNC-machined geometry for reproducible tolerances and precisely defined internal volumes
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High-quality wood-based materials (plywood / solid wood depending on version) with deliberately dimensioned wall thicknesses
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Internal structure and damping are strictly functional: controlled rear-space energy, minimization of standing waves, no decorative cavities
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Surface finishes and wood species are defined on a project-specific basis
Optional:
For a small number of uncompromising customers, a version manufactured entirely from Panzerholz is available — maximizing mechanical calmness without regard to effort or weight.
Who is this Supravox 285-EXC enclosure designed for?
LMH Classic Line
High-frequency horn
System Architecture
The system is designed consistently around the Supravox 285-EXC (mk2) — a high-efficiency 28.5 cm bass / lower-midrange driver with a field-coil motor.
The driver is not conceived as a conventional hi-fi woofer, but for direct, controlled reproduction in the bass and lower midrange.
Driver
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Supravox 285-EXC (mk2)
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Nominal diameter: 285 mm (12″ class)
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Impedance: 8 Ω
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Field-coil motor with external power supply
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Operating range (manufacturer specification): approx. 50 Hz – 7 kHz
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High efficiency, dependent on field strength (typically approx. 93–102 dB / 1 W / 1 m)
The adjustable field strength allows targeted control of efficiency, damping, and dynamic behavior.
This enables precise matching of the driver to room, amplifier, and overall system concept.
Enclosure principle
At LMH, the 285-EXC does not operate in a conventional bass reflex or sealed enclosure, but in a heavily damped baffle compensé / RJ-Wedge configuration.
The rear space is deliberately designed to dissipate energy and prevent resonance-supported behavior.
This principle enables:
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clean transient response
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controlled lower-midrange reproduction
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minimal cabinet coloration
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no port noise or airflow artifacts
The driver couples to the room primarily via the baffle surface rather than through a resonant air volume.
System integration
The system can be used in two ways:
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Puristically as a single-way system for bass and lower-midrange reproduction
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As a lower-midrange module combined with a separate high-frequency system
(e.g. horn or super-tweeter, passively or actively integrated)
The specific configuration — damping, crossover points, and optional high-frequency augmentation — is defined on a project basis and tailored to room size, listening distance, and target performance.
Driver options & implementation
LMH offers the enclosure either:
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without driver (for existing 285-EXC units)
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as a complete system including driver and field-coil power supply
Tuning and integration are always carried out with the objective of preserving the characteristic, direct sound of the 285-EXC — not smoothing or neutralizing it.
Design Driven by Acoustics
At LMH, design consistently follows acoustic function.
Material selection, surface treatment, and construction are not decorative elements, but integral parts of the mechanical and acoustic design.
Solid Wood – Where It Makes Sense and Remains Stable
Where it is structurally and acoustically meaningful, we also build enclosures from carefully selected solid woods.
We use only woods with proven long-term stability, defined density, and good internal damping, such as:
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Beech
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Maple
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Oak
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Ash
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Walnut
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Selected tropical hardwoods (project-dependent)
Solid wood is used deliberately – not universally – only where mass, stiffness, and resonance behavior benefit from it and where climatic influences remain controllable.
Veneer on Plywood – The Technically Preferred Solution
In many cases, veneered plywood is the acoustically and mechanically superior solution.
As a core material, we use high-quality beech or birch plywood with excellent dimensional stability and uniform resonance behavior.
This core is finished with real wood veneers in virtually any available species – chosen for visual reasons without sacrificing the structural advantages of plywood.
This construction offers:
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High long-term stability
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Low tendency to warp or crack
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Reproducible acoustic properties
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Free choice of wood appearance without structural drawbacks
At LMH, veneer is not a compromise, but a deliberately chosen high-end solution.
Stains & Wood Surfaces
Wherever possible, the natural wood structure remains visible.
We use:
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Transparent stains to emphasize the grain
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Oil and hardwax systems for open, lively surfaces
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Satin-matte lacquers with minimal film thickness
Surface finishes are defined on a project basis, matched to wood species, geometry, and acoustic targets.
Paint Finish (Optional)
Where it makes sense from a design or conceptual perspective, fully painted versions are also possible.
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Color selection in nearly all RAL shades
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Opaque or satin finishes
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Multi-layer, mechanically stable paint systems
At LMH, painted finishes are not a standard solution, but a consciously chosen alternative to wood or veneer surfaces.
Project-Specific Configuration
Every LMH product is configured on a project-specific basis.
Wood species, veneer, stain, or paint finish are integral parts of the overall design – not interchangeable accessories.
The goal is a permanently stable, mechanically quiet, and visually honest system that does justice to the respective loudspeaker or enclosure concept.
System
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Damped baffle compensé / RJ-Wedge principle (no bass reflex)
Driver
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Supravox 285-EXC (mk2), 8 Ω
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Field-coil motor with external power supply
Key specifications (driver, manufacturer data)
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Bandwidth: approx. 50 Hz – 7 kHz
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Efficiency: field-strength dependent (approx. 93–102 dB / 1 W / 1 m at Fs)
Installation / dimensions (driver)
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Cutout (drilling): 280 mm
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Depth: 180 mm
Operation
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Passive (purist) operation or integration within a larger system
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Particularly suitable for tube and low-power amplifiers due to high efficiency
Note
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Final tuning and system scope (e.g. high-frequency extension, damping, terminals) are defined on a project-specific basis.
