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A Short Lowther PageLowther drivers are extremely high fidelity full range drivers built by the Lowther company in the United Kingdom. These drivers have high magnet strengths producing large Bl products, and this together with the very light paper cone material produces a driver with excellent transient response and low distortion. The design of the driver results in a rising frequency response (when measured in open air or in an open baffle), so to restore low frequency sound pressure, a rear loaded horn is usually used. DriversLowther drivers come in three flavours: Alnico magnet (A series), Ferrite magnet (C series), and neodynium magnet (DX and EX series). The "traditional" drivers are the alnicos. A seriesPM6A, PM7A, PM2A, PM5, PM4. All these drivers are relatively similar in construction, the major difference being the strength of the magnetic flux, which increases from 1.75 Tesla for the PM6A through to 2.4 Tesla for the PM4. The magnets are big, heavy, and costly. They put a lot of stress on the frame which can buckle or distort over time leading to rubbing of the voice coil. Enthusiasts suggest rotating the driver 180 degrees to even out the load on the frame. High efficiency drivers, 98 to 100 dB sensitivity. C series45C, 55C, PM6C, PM7C, PM2C. The "cheap" Lowthers, generally less often used than the other series. Iron magnet, lower efficiency. DX & EX seriesDX2, DX3, DX4, EX2, EX3, EX4. These are the new neodynium magnet drivers. The magnet material is less costly to make than the alnico and is also smaller and lighter for a similar magnetic strength. The DX series have an open back, the EX use a new semi-closed surround on the rear with ports which probably results in some kind of filtering of the back wave. New!Lowther have released a whizzer cone with a rolled lip, similar I guess to the Hammer Dynamics Super 12 driver with it's rolled lip on the large whizzer cone. Apparently this reduces a lot of the resonance problems. Lowther are claiming the driver cone is much better than the old one. CabinetsThe Lowther-designed cabinet options are well listed at Marc Wauters Lowther page. Other cabinet designs can be found on the Rear-Loaded Horn page and in the DIY projects on this website. Most full range Lowther speakers use a rear-loaded horn to improve the bass response. A horn is the most efficient way of producing bass from the Lowther driver, but needs to be large (even very large) to produce good quality bass down at low frequencies (40 Hz or less). Some people claim good results with Lowthers in vented boxes, see more under Box Enclosures. Bert Doppenberg has put the Lowther (and now AER drivers) into front-loaded horns, and removed the duty of producing low bass to a dedicated bass unit (using bass drivers in bass reflex cabinets, or bass horns, etc.). Ed's open baffle Lowthers. How does he do it?? With supporting subwoofer and Behringer Ultracurve frequency equalization. DIY and Repair
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