FTX Common Motor Coaxial Drivers

Celestion’s FTX coaxial range represents a major step forward in coaxial driver technology. Each FTX driver features fully combined Low Frequency (LF) and High Frequency (HF) components which are powered by a Common Magnet Motor Assembly, where the same ferrite magnet is used to drive both elements.

June 26, 2018




Coaxial loudspeakers offer full range frequency response in a single self-contained driver. By concentrically aligning low and high frequency drivers, they can act as a single source, often providing improvements in signal coherence when compared to a traditional two-way system. An immediate benefit of this is that they can provide an effective, high quality solution to sound reinforcement applications where size, weight and off-axis response are critical. 

Celestion’s FTX coaxial range represents a major step forward in coaxial driver technology. Each FTX driver features fully combined Low Frequency (LF) and High Frequency (HF) components which are powered by a Common Magnet Motor Assembly, where the same ferrite magnet is used to drive both elements. This precision-designed magnet assembly has been optimised using finite element analysis techniques so that it distributes magnetic flux to both LF and HF voice coil gaps in the most efficient way possible, thereby extracting optimum performance from the system.  

By designing the magnet assembly in this way, the voice coils and hence the acoustic centres of the two components are brought closer together compared to those of a conventional coaxial driver. It delivers further improvements in signal coherence and time alignment for more natural sounding audio reproduction. The use of a single magnet assembly also means lighter weight and a profile that is more compact than conventional coaxial designs. 

Each of the models in the FTX range features a polyimide film HF diaphragm, enabling them to offer increased HF power handling. The diaphragm is fixed using Celestion’s Sound Castle soft clamping assembly, which reduces the stresses associated with holding the diaphragm in place, decreasing distortion and ensuring reliability of performance. 

Both HF and LF voice coils are edge wound, using either lightweight copper, copper clad aluminium or pure aluminium. The flat-edged profile of the wire adds to the barrel stiffness of the voice coil former (further reducing the likelihood of distortion), and also enables a closer packing density, which leads to improved cooling and greater motor strength. 

Each driver in the range features aluminium demodulation rings as standard. These act to make the variation of system inductance more linear as input current varies, delivering improved sensitivity at higher frequencies. They also substantially reduce the harmonic and intermodulation distortion associated with voice coil displacement.

FTX coaxial drivers are available as standard, off-the-shelf products in a range of chassis sizes, from 6.5-inch to 15-inch diameter. As product platforms they can also be adapted and customised by Celestion’s engineering team to meet a system builder’s project-specific requirements.
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