Alpine Develops Thin Subwoofer To Generate Bass In Restricted Automotive Space

High bass performance now available to a range of cars that previously couldn’t accommodate subwoofers.

Alpine Electronics, the in car multimedia specialist, has developed a novel subwoofer that offers the possibility to offer excellent low frequency performance in vehicles that couldn’t previously accommodate a bulky, square enclosure.  Sports cars, SUVs and saloons could benefit from bass performance that equates to that of a traditional 12” subwoofer yet only measures some 100mm deep.

“Traditional subwoofer enclosures need to move large volumes of air to be effective, therefore they tend to be bulky,” says Alpine’s OEM business manager Keith Price. “Our solution allows us to offer excellent bass in vehicles that couldn’t afford to sacrifice such a large package volume to the subwoofer.”

As consumer demand increases for great sound reproduction in the car, vehicle manufacturers are looking for ways to offer performance using any available package space.  The solution from Alpine can be installed in an area 100mm deep. This has been achieved through the development of a specific pair of 165mm speakers that have a long throw and deliver extreme magnetic force. The two units combined, offer the equivalent of 200g of moving mass, approximately the same as a bulky traditional 12” unit.  An additional option is to combine the amplifier in the unit reducing wiring complexity.

With the design package fixed, Alpine’s engineering team used Parametric Acoustic Modelling (PAM) software from ITI plc to analyse the enclosure’s performance.  PAM consists of two parts; proprietary modelling software and patented waveguide arrangements. The modelling software treats an acoustic enclosure as an arrangement of waveguides with distributed parameters, as distinct from the traditional method of modelling which treats volumes and ducts as lumped parameters. Accordingly, PAM software accurately tracks the behaviour of acoustic waves even after numerous reflections. The designer is able to add one or more impedance discontinuities to optimise cone excursion, frequency response, group delay and transient behaviour.

The final element was to tune the subwoofer enclosure to vehicle interior and requirements set by the customer.  At the firm’s Technology Evaluation Centre in Coventry, Alpine uses sound rooms where vehicles can be isolated and detailed measurement and adjustment is possible. Alpine uses acoustic filters to boost the low frequencies and attenuate the “above band”. The result is clear, tight bass.

The technology is the latest in a line of compact subwoofers that Alpine has developed to solve package or weight issues.  These include the DLP subwoofer that can be fitted in the passenger footwell or horn subwoofer for under seat applications.

19 May 2008 Staff

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