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Fostex FE206En Fullrange Speaker Driver (Transducer)


Fostex FE206En Fullrange Speaker Driver (Transducer)

The Fostex FE206En fullrange driver is the updated model of the Fostex FE206E. The data sheet indicates that the FE206En model uses a new diaphragm material which aids in improving the mid to high frequency reproduction. The driver is 200 mm (7.9") in diameter and constructed on a stamped steel frame. Like the similar FE driver the "ES cone" is made from banana plant fibre. The light weight paper cone is attached with a reverse roll surround made from treated cloth. The ferrite magnet is huge, 146 mm (5.75") in diameter, weighing 1067 grams (2.3 lbs). The overall weight of he driver is 3200 grams (7 lbs). The FE206En has a low Qts which makes this driver most useful in horn type enclosures. A speaker box plan of a back loaded horn type enclosure was included with the data sheet.

Fostex FE206En Full-range Speaker Driver

Fostex FE206En Fullrange Speaker Driver

The frame is stamped steel and relatively light so there are benefits to adding mass (dampen) to reduce the potential of having the chassis "ring". Common methods are to use electrical duct seal or adhesive bitumen damping material. It is also a good idea to cover The surface of the large magnet could act like a reflective surface in the enclosure so it is a good idea to cover the magnet with a sound absorbent material (like upholstery felt). For additional details and photos see the Fostex FE206E / FE206En driver modifications and tweaks page.


Thiele/Small (T/S) Parameters - Fostex FE206En Driver

The Thiele/Small Parameters from the Fostex FE206En driver data sheet are summarized in the table below.

Thiele/Small (T/S) Parameters - Fostex FE206En Fullrange Driver

 Parameter  Fostex
Fs 45 Hz
Vas 70.99 L
Qts 0.19
Qes 0.194
Qms 4.57
Re 6.8 Ohms
Le  0.0525 mH 
SPL 96 dB

Fostex FE206En Frequency Response and Impedance

Fostex FE206En Frequency Response and Impedance

The strong peak (about 8dB) at 2.6kHz results in a quite forward midrange. A parallel notch filter can be used to tame this peak. The rising response with increasing frequency is a typical trait of extended-range transducers with a very strong motor. This rising response is best compensated by positioning the speakers off of the listening axis (ie. speaker toe-in). Start with a speaker toe-in of about 30-degrees and adjust to personal taste.


Datasheet - Fostex FE206En


Fostex FE206En Double Bass Reflex Type Enclosure

The speaker box plan Double Bass Reflex Type Enclosure for the Fostex FE206En full range speaker unit is show below. Mark Houston has built a couple of the double bass reflex enclosures with the Fostex FE206En driver.

Fostex FE206En Double Bass Reflex Enclosure Plans

Fostex FE206En Double Bass Reflex Enclosure Plans

The speaker box plan is from the Fostex FE206En data sheet and included these comments.

"FE206En is designed for use in a back loaded horn type enclosure and it is generally unsuitable for bass reflex because of its over damping sound characteristics. However, it is possible to use the FE206En in a bass reflex enclosure as shown. This example is a narrow and tall style bass reflex type enclosure. Internal volume of 45 liters tuned to approximately 50Hz (Fb). Low frequency response from around 120Hz is gently damped with a controlled peak at 50-60Hz."


Enclosure Plans and Projects Links - Fostex FE206En