|Ekta Grande, built by David/UK
Copyright 2010 © Troels Gravesen
Thank you so much for your excellent work on the Ekta Grande, I have just completed these after starting in November 09.
After much experimenting with enclosure materials, I came to the conclusion that I would produce a stiffer (using tile cement with MDF/PLY) enclosure utilising curved walls, aka. Cremona. (Sonus Faber fogive me, but I love the shape) I used 3 layers of slotted 6mm MDF, filled with tile cement, the final fourth layer being 4mm birch ply, resulting in virtually transmissionless walls. The entire interiors were given 3 coats of rubberised floor paint and damped at their nodes with bitumen sound deadening pads.
I used Maple veneer, stained with spirit orange then sanded down and sprayed with 8 coats of catalyst lacquer, rubbed between coats. The veneer was applied using contact adhesive and although I managed to get it positioned well, I would use a different adhesive if doing again. The enclosures were lined with heavy 12mm cotton jute industrial carpet underlay, the bass sections were each filled with long haired sheeps wool along with the top and bottoms and each mid enclosure's rear walls were cover with a double layer of MDM3. The front panels are black leathercloth.
The end resulted in a very worthwhile project -- however I had to see an Osteopath (trapped a nerve) at one time -- they each weigh 44Kgs
Only simple hand tools were used throughout, plus of course a router.
You may have noticed I have made my own "Tozawa" type of resonators in the bass sections -- they really do work -- reducing the amount of filling needed, I am paticularly pleased with these, as - it leads to a more coherent bass resolution. Total volume is 72.0 litres -- Bass volume being 58.62 litres. The ports were initially held in the 32mm thick Birch/Perspex laminated rear spine with plasticine -- after successfully tuning to 30Hz they were removed and finally bonded with clear Styroflex grab adhesive.
The filters were all placed in such a way as to be far enough away from the magnetic fields of the drivers, yet able to be removed easily if necessary.
I am completely blown away by the sheer musicality of these -- The lower registers descend with precision, reflecting every note -- mids are very slightly forward, ( my taste ) with excellent clean transients, the XT25TG tweeter also sounds smooth and extended with good transients, clearly a good choice.
Have a very Happy Christmas,
Best Regards, David