Longstroke Subwoofer

A modification was requested for a professional studio monitor where the wooferchannel consisted of a pair of 8 inch long excursion low note drivers mounted in a closed cabinet. The setup includes a Pascal class D module driving both woofers in paralel and an IOT connected DSP providing extensive adaption to roommodes.

Extended polepiece

To address distortion caused by a voicecoil leaving the linear zone of the magnectic forcefield as it travels towards Xmax driver manufacturers have equipped motor assemblies with extended polepieces. Usage of a standard StarBass accelerometer was investigated but removal of the dustcap revealed usage of such polepiece effectively ruling out the use of incoil mounted accelerometers such as the StarBass V and VI.


To offer a solution research was started into the development of a sensor geared towards use with drivers equipped with an extended pole. The design is based upon the already proven sensor technique of the existing starbass sensors but the sensor assembly lacks supporting legs and is designed to be mounted directly on the outside of the driver cone. Although not mating the accelerometer directly to the voicecoil results in a considerably drop in sensor bandwidth measurements have indicated that it's frequency response remains sufficient for use with subwoofers operating between 20-100 hz.

Easy mounting

A welcome sideeffect of the ClingOn mounting method is that removal of the driver dustcap is no longer required resulting in a considerably drop in time needed to perform the modification process. For testing purposes a standard Starbass connection strip is used which at a later time can be replaced by custom designs to cater for tight integration with existing cableing setup.