This is my old system. The ribbons were originally made by Trevor Lees in Melbourne, Australia, and were later re-ribboned by Tony Moore. Tony's ribbon is just under 4 Ohms resistive and is very rugged. Unlike many other ribbons and planer magnetics, the ends of the four aluminium leaves are soldered to, which improves reliability. This re-ribboning overcame shortcomings in the original design. The ribbons were crossed over actively at 280Hz, fourth order butterworth, to the subwoofers. The two sub-woofer boxes which can be seen in the corners use Peerless 831857 12" CC line drivers in a 160 litre box tuned to 18Hz. This system could provide massive outputs (Thanks to the 3 KW of drive) and was very detailed and articulate. For an idea of the size of this system, the back wall is 7 metres long, and that's a piano between the ribbons.
There is a lot more on this system on Bill Alford's hompage. The low SAF of the four piece system forced a reluctant sale. L
A few people have been enquiring about the Peerless 831857 subwoofers used in this system. I've included some sketches that I had lying around for the boxes. The pictures on Bill's page will tell you a bit more. Total volume of the box is 160 litres. The port is 100mm dia and 400mm long. All MDF is 25mm. Three 2400mm x 1200mm sheets required for two boxes. Outside dimensions are 600mm wide, 610mm high (plus feet) and 650mm deep. Consistent sizing of the braces is essential to the proper fit of these boxes. A table saw makes this job very easy. The port is radiused with a 25mm round over bit in the router.
Material list (All 25mm MDF)
Front and Back 600x610mm x2
Sides 585x600 x2
Braces 550x550 x4
Top 600x600 x1
Bottom 550x600 x1
Specs for the 831857
|Sensitivity 1W/1m||89.3 dB||Lin. & Max. excursion||±9 & ±11mm|
|Free Air Resonance||24 Hz||BL||11.6|
|DC resistance||5.5 Ohms||Moving mass incl. air||80.2 g|
|V.C. inductance||2.8 mH||Vas||210 ltr|
|Power handling||220 W||Qms||3.72|
|Effective cone area||520 cm^2||Qes||.49|
|V.C. diameter||42 mm||Qts||.44|
|V.C. height||25 mm|
|Air gap height||7 mm|
New 12" woofer in the CC line. It has the same long voice coil as the 10" 831727 but to obtain optimal parameters with the extra heavy moving system, a new and even heavier magnet has been used. It also has a rubber surround and a thick polypropylene cone. Not less than 46oz. magnet and of course a short circuiting ring and all the well known features of the CC line.