These improvements were devised and implemented during the Covid-19 lockdown period. I would like to thank Trade CNC/Rapid 3D Solutions Ltd, Northwich (https://tradecnc.co.uk) (the beech plinth, hand router templates and composite components) and Sparta Ltd (http://www.sparta.co.uk), Burnley (bespoke inserts, BMR drive unit chassis reinforcement and floor coupling system), for delivering their excellent work during these challenging times. The cabinets were made pre-lockdown by Simon McLay of McLay Furniture (https://www.mclayfurniture.com). All wood surfaces have been hand finished using Littlefair’s wood finishing products (https://www.littlefairs.shop)
The improvements to the design are summarised below.
The slate plinth has been replaced with a 40 mm thick machined beech plinth that incorporates the equalization network and connection panel. The form of the curved cabinet is no longer interrupted by the cable connections. The plinth now comes pre-attached; it is only the spikes that need to be added. The plinth has been stained black ebony to highlight the curvature of the cabinet.
A bespoke M12 spike system has been designed, with large diameter spike shoes included for hard floors. The spike shoes are fitted with a cork based damping material for optimized floor interface. The profile of the spike has been designed to separate, rather than cut, fibres in carpet backing underlay backing. Spikes can be adjusted with a tommy bar and locked via the half-nuts. There is enough adjustment travel to allow axial optimization for a range of listening seat heights.
Gold plated tellurium-copper binding posts replace the 4 mm socket connections – the types chosen are not overly massive for reduced eddy current effects; it is now possible to use spade / bare wire connection as well as 4 mm plugs. The cellulose textile based composite connector panel is isolated from the plinth via an elastomer lined mounting system.
Transfer of the equalization network from inside the cabinet to the plinth leads to much reduced component vibration; even with compliantly mounted components acoustic coupling makes it impossible to eliminate vibration if the network is inside the cabinet. The speaker cables are now more directly connected to the equalization network.
The network is now easily accessible via a composite access panel for bespoke tuning. The resistor has been upgraded to a modified Mundorf Supreme non-inductive wire wound type, the tab mounting enables solderless resistor changes to tailor sound quality to individual tastes and rooms. The network can also be easily bypassed for systems that incorporate digital equalisation and room correction. Heavier gauge Gekko Cable is now used to connect the network to the drive unit.
The BMR drive unit chassis is now structurally reinforced with a laser cut 3 mm stainless steel mount reinforcing element.
The original slate based Curvi-BMR already achieves a remarkably high level of sound quality, as described by David Price in his StereoNet review. These seemingly minor design changes have led to improvements in stereo image quality and dynamics. The speaker scored highly in these aspects before, but improvements are nonetheless there to be heard. There is also more bass weight with improved texture. Treble and mid-range are now even more natural sounding.
Contact for more information:
Designer of the Curvi speakers