Design Rationale

CML Audio firmly believe that effective recreation of a musical event in the home listening room is most effectively achieved if the temporal information in the signal is left intact and not corrupted by dividing the reproduced frequencies between two or more drive units. If this division occurs in the 2 kHz to 3 kHz range, as is usually the case, irreversible damage is done as the ear is very sensitive to phase disturbances in this region. The resulting loss of coherence and poor impulse behaviour become apparent when comparing the reproduced sound with the live event and that from a properly loaded high performance wide-band drive unit, as encountered in Etude and Curvi products.

The Etude 1 is a 10 litre sealed box stand-mount design that utilises newly developed balanced mode radiator drive units. It is designed to bring the CML Audio experience and design philosophy to a lower price point, and to raise the bar for stand mount loudspeaker performance at that price level.

The Etude 1 has been voiced for free space installation on good quality loudspeaker stands, though in some room / system combinations installation close to a rear wall can also work well. In terms of sensitivity the Etude 1 normal (87 dB/W) for its size, and the impedance stays above 6 ohms. Power handling may be conservatively rated at about 50 W.

In the Etude 1

the full frequency range of the speaker is produced using the BMR drive unit. The mode of action of such a drive unit is very nicely described in Martin Collom's latest edition of High Performance Loudspeakers. In summary the BMR drive unit consists of a flat light but stiff disc that is driven by a conventional voice coil and is supported by the familiar suspension arrangement. At low frequencies the disc predictably behaves as a normal pistonic drive unit. However as frequency increases, to what would normally be the first breakup mode, the clever part begins and the role of strategically placed radial masses becomes vitally important.

The masses control the vibration harmonics of the disc such that what is normally considered uncontrolled breakup becomes highly controlled; the disc is no longer a piston but a radially bending disc (imagine the shape described by a guitar string that is fixed at one end whilst vibrating at its 2nd harmonic, and at the same time is being rotated at its free end about the fixed point - the shape will be a bit like that observed in water when a stone is thrown in to a puddle). In this vibration mode it is the bending waves in the disc that perturb the air molecules. These give rise to the excellent off-axis coupling that is unique to BMR and which results in a wide listening window - good tonal balance is achieved even when listening far off-axis. The BMR driver used in the Etude 1 is a derivative of the original BMR design.

- For a close-up view of the drive unit | Click here

The two BMR drive units in the Etude 1

are series connected but the lower unit has an attenuated high frequency response in order to avoid development of line source behaviour and the associated lobing effects. In other words the Etude 1 behaves close to a true point source, resulting in excellent resolution of reproduced instrument placement within the sound stage.

Baffle step compensation is achieved via a three element filter that consists of top quality components including a Vishay thick film resistor. The internal wiring is silicone elastomer insulated good vibration damping is combined with low dielectric absorption.

The bending wave operation of BMR drive units places greater demands on the structural integrity of the drive unit basket/frame and driver mounting relative to conventional pistonic drive units. In the Etude 1 the driver basket is structurally reinforced with a CNC water jet cut steel element that is bonded in place with industrial adhesive. The drivers are compliantly mounted on to the cabinet using elastomeric components specifically formulated and designed for dissipation of vibration energy. Metal to metal contact is kept to an absolute minimum.

The BMR drive units are loaded

By a sealed box of about 10 litres volume which is critically braced with hardwood and steel members. The rectangular cabinet walls are divided into asymmetric shapes by hardwood beams that are glued into grooves, this approach attenuates and broadens structural resonant peaks such that they become inconsequential. The front and rear panels are constrained layer laminates. The front panel (baffle) is faced with a 12 mm thick slab of Corian® that is CNC machined to accommodate the drive units and their mounting hardware. The baffles are available in white or a granite black as standard, though paint finishes are available at extra cost. The cabinets are finished in satin epoxy lacquer with black or white being the standard colours; any colour is available at extra cost.

- For an internal view of the cabinet | Click here