Fostex FE-108 Σ
FE-108 Σ is the smallest model of the legendary Sigma series. Unlike the bigger models it has half-roll surround and a dust cap instead of a whizzer cone.
This is the manufacturer's brochure
My Measurements
| Driver Properties | Thiele - Small Parameters | ||||
|---|---|---|---|---|---|
| Chassis material | Vacuum Molded Aluminum Alloy | Parameter | Measured | Datasheet | |
| Membrane material | Banana Pulp Paper | Fs | 70.5Hz | 80 Hz | |
| Magnet System | Ferrite | Re | 6.5 Ω | 6.5 Ω | |
| Surround | Cloth | Qms | 2.10 | 2.21 | |
| Voice Coil Diameter | 26 mm | Qes | 0.21 | 0.22 | |
| Nominal Impedance | 8 Ω | Qts | 0.19 | 0.20 | |
| Sensitivity | 92 dB/W/m | Vas | 10.3 ltr | 7.07 ltr | |
| Rated Power | 5W | Le | 0.25 mH | N/A | |
Frequency response at 1m with 2.83 V input RED - on axis, BLUE - 15 º off axis, GREEN - 30 º off axis
The second, third and fourth harmonic curves measured at 2.83V input RMS.
Burst decay response, measured at 1m on axis
The impedance curve in 18 ltr sealed box
Conclusion
This driver has a typical T/S parameters for a backloaded horn applications. It keeps the excellent sound signature of the Sigma series with surprising solid sound performance for its dimensions.
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