Betetec Industries Pty. Ltd.
17 DeHavilland Crescent, Ballina, NSW

Brands: Aaron, Hyperboloid

Hume L'Estrange designed and manufactured loudspeakers and speaker enclosures from 1988 for the Hi-Fi and home theatre market. He ceased production in 2016 when he retired.

L’Estrange designed and manufacturing speakers from 1988 and set up Betetec Industries Pty. Ltd. in 1999 to market his products from Ballina NSW.

He manufactured Aaron brand speaker enclosures using special speaker drivers he termed Hyperboloid, with no dust caps and mounted low noise surrounds giving them a clean and smooth sound.

The following extract from a review of the Aaron HMF-600 Speakers appearing in Australian HiFi Reviews in 2011 describes the hyperboloid design:

"Aaron’s HMF-600MkII is a four-driver, three-way floor-standing bass reflex design. Because the two 168mm-diameter bass drivers have hyperboloid diaphragms, I will have to use the word ‘diaphragm’ to refer to them, because, unlike almost all other bass driver diaphragms, they are not ‘cones’. The peculiar diaphragm profile not only eliminates standing waves, but also means that L’Estrange could eliminate the troublesome and weighty dust cap, thus reducing mass. Speaking of which, the diaphragm itself is already extraordinarily low in mass, being made from a carbon-coated laminated paper. Also, unlike most drivers, the voice coil is not fixed to the cone at its centre. Instead L’Estrange uses something like a ‘miniature cone’ beneath the hyperboloid diaphragm so the voice coil ends up driving the hyperboloid diaphragm at one third of its circumference rather than at the centre, like normal designs. And yes, I know that Mordaunt-Short also uses a similar technique in its high-end designs, but Aaron beat M-S to the punch by several years! This system makes the driver diaphragm exceptionally rigid, so cone motion is almost perfectly piston-like at low-frequencies, which is the Holy Grail for all driver designers. As for the voice coil itself, it is 25mm in diameter and comprised of polyesterimide coated copper wire, insulated with a Class H modified polyester resin. This wire has excellent thermal endurance, solvent resistance and exhibits a low coefficient of friction to improve windability, and it’s wrapped around a solid but light-weight aluminium former. The driver chassis is pressed steel at the end of which is a substantially sized, centre-vented magnet, to the rear of which is attached a secondary, flux-cancelling magnet. Whereas all previous Aaron drivers have used impregnated cloth surround suspensions rather than the more usual foams and rubbers, the flexible suspension on the HMF-600MkII is made from a unique plastomer called ‘aerated polyurethane’ which L’Estrange says is lighter than rubber, lasts longer, and doesn’t harden with age but has rubber’s damping characteristics. A final design improvement related to the roll surround is a unique overlapping trim ring. In Aaron’s design, the trim ring overlaps the surround, which L’Estrange says reduces turbulence.

At 300Hz, the two bass drivers are crossed to the single 132mm midrange driver which, like the bass drivers, also has a hyperboloid cone and the same voice-coil/cone coupling system. This driver, in turn, is crossed over at 5kHz to a 25mm Vifa XT25 dual ring radiator tweeter, with its characteristic centre wave-guide."

Hyperboloid Speakers, this is our latest technology using special speaker drivers using no dust caps and low noise surrounds making them the cleanest most smooth sound around.

The company ceased production in 2016 when L’Estrange retired.