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The professional sound reinforcement market, especially in the live touring field, is constantly looking for higher performances as well as finding new ways to reduce size and weight of the systems. In order to maintain the technology leadership in the subwoofer field, 18 Sound has introduced the Tetracoil technology, where four mobile voice coils are used into a dual-gap magnetic motor. Such configuration, in addition to increasing the applicable power, linearizes speaker behavior by significantly reducing the distortion and significantly increases the power vs. weight ratio. 

In its traditional form, the loudspeaker is an object with nonlinear behavior, as it does not proportionally convert the electric power supplied by the amplifier to acoustic energy into the environment. Nonlinearity is synonymous with sound distortion, which especially at the high levels that can be reached during live concerts can reach values well above 10%. Over time, various techniques have emerged to limit this problem; the main limit is that each of them operates in a limited frequency range and this introduces additional side effects. In the particular case of subwoofers, one or more aluminum rings positioned in the magnetic gap are used resulting in a partial reduction of the distortion rate. The side effect is the introduction of a sensitive magnetic field asymmetry in the gap, where the moving coil is to operate.

Tetracoil technology corrects most non-linearity at the base, making the speaker lighter and easier to build. In fact, this particular type of realization allows to optimize the amount of needed magnetic material and increases by at least 50% the heating exchange of the voice coil, and consequently the power handling is significantly improved as well.

The 15TLW3000 15” Tetracoil subwoofer 

During the Pro Light + Sound show held in Frankfurt in April, 18 Sound have introduced two new Tetracoil subwoofers. The first one is the 15TLW3000, a 15-inch diameter version of the 18TLW3000, model that have been adopted by several reference manufacturers in their top-of-the-range subwoofer cabinets. The 4-inch - 100mm Tetracoil engine, characterized by the rear die-cast aluminum heat sink made of, equips both models. The 15TLW3000 is now shippingout from our Reggio Emilia factory.

The new 21NTLWL5000, a 21” – 540 mm – neodymium tetracoil subwoofer

18 Sound is now introducing the 5000 Tetracoil subwoofer family, equipped with a new generation 4.5 inch - 115mm - Neodymium magnet engine.

The first model to be released will be the 21NTLW5000, a 21-inch diameter speaker reproducing frequencies down to 20 Hz at very high-pressure levels - 130dB. Preliminary specs are available here.

A target sought by the most renowned professional subwoofer manufacturers is to increase linear excursion of the membrane. To do so you need to control significant moving masses at very low frequencies for several centimeter membrane excursions. To achieve this goal, in the new 21-inch a lot of efforts have been spent using simulation techniques for defining the suspension geometry, which have been designed and produced specifically for this model.

The 21NTLW5000 is capable of handling power levels of 4000W. The speaker is currently under test by the world's leading sound reinforcement manufacturers. The first production is scheduled for the fourth quarter of 2017.

18 Sound R&D is working on the 18-inch version that is already in an advanced development phase. The benefits of Tetracoil technology will be then applied to smaller speaker diameters. A 3.5-inch motor to be followed by a 2.5-inch engine is already in the pipeline.

For more information on Tetracoil technology, you can visit the 18 Sound site



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