KLIAVS: Focal's electromagnetic woofers
A pair of Focal Stella Utopia EM speakers will be on demo at the Audio Perfectionist room on the 4th floor.
|Focal Stella Utopia EM speaker.|
The Stella Utopia EM, which costs around RM400,000, is one model below the top-of-range Grande Utopia EM.
Asia Sound, which used to be the distributor for Focal in Malaysia/Singapore, brought in a pair of Grande Utopia EM speakers late last year but they were delivered directly to the Malaysian buyer and audiophiles were denied the chance to hear them.
At the Audio Perfectionist room, the Focal Stella Utopia EM will be partnered with McIntosh pre and monoblock power amps and CD player.
From the Focal website: "The permanent magnet is limited in power and in the framework of a reference woofer, it’s a real problem. Because a woofer should at least combine two essential performances: high efficiency and ability to go down in the low frequencies.
"To go down in frequencies, Focal can adjust the surround and the spider flexibility, but we should above all increase the cone weight. If we increase the cone weight, the efficiency drops. And to compensate this drop, we have to Increase the magnet power. That’s where the limits of the permanent magnet step in, forcing a compromise between efficiency and resonance frequency.
"Only solution for Focal, reconsidering the very existence of the permanent magnet...
"We adopted an Electro-Magnet for our new 16” (40cm) woofer (for the Grande Utopia EM; the Stella Utopia EM uses 13-inch woofers) Thanks to the simulation software and to the existing materials, this extreme solution goes back to the very origins of the driver and was optimized to supply the expected force (patent pending). The magnetic field in the air gap reaches 1.75 Tesla (0.9 for the woofer of the previous Grande Utopia Be that was yet equipped with a Multiferrite magnet) to supply a force factor (the real power of the motor) of 34T.m.
"The goal is reached: the efficiency for 1W @ 1m reaches97dB, whereas the resonance frequency drops to less than 24Hz.
"The Focal EM Electro-Magnet is made of a 15.4lb (7kg) copper coil. The motor including the coil weighs 48.5lb (22kg). The 16” reaches a total weight of 52.9lb (24kg)."
The Stella Utopia EM is a three-way speaker using an Electro-Magnetic 13" (33cm) "W" woofer; 2 Power Flower 6-1/2" (16.5cm) "W" midrange drivers; and an IAL2 pure Beryllium inverted dome 1" (27mm) tweeter.
Its frequency response is rated to be 22Hz - 40kHz; sensitivity at 94dB; nomimal impedance at 8 Ohms and crossover frequencies at 220Hz and 2,200Hz. They are large - (HxWxD) 61-1/3" x 21-3/4" x 32-11/16" - and heavy speakers - 363.76lb (165kg) each.