Fostex FE108SS-HP
Best box: 4.3 L bass reflex tuned to 79.4 Hz · F3 76.4 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Fostex FE108SS-HP does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- Xmax is not published, so the port size is an empirical estimate (area ≥ 12 in² per ft³ of net volume, minimum by driver size), not a displacement calculation. Check air velocity in Load Forge Studio.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 4.3 Liters |
| Tuning Frequency (Fb) | 79.4 Hz |
| F3 (-3 dB Cutoff) | 76.4 Hz |
| F6 / F10 Extension | 68.1 Hz / 60.2 Hz |
| Port Inner Diameter ESTIMATED | Ø 5.0 cm |
| Port Physical Length | 18.1 cm |
| First Pipe Resonance | 948.0 Hz |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 1.9 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 142.8 Hz |
| F3 (-3 dB Cutoff) | 144.7 Hz |
| F6 / F10 Extension | 109.1 Hz / 82.1 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 81.0 Hz |
| Total Q (Qts) | 0.39 |
| Electrical Q (Qes) | 0.431 |
| Mechanical Q (Qms) | 4.13 |
| Equivalent Volume (Vas) | 4.3 Liters |
| Diaphragm Area (Sd) | 50.3 cm² |
| DC Resistance (Re) | 7.3 Ω |
| Efficiency Bandwidth Product (EBP) | 188.1 |
| Linear Excursion (Xmax) | N/A mm |
| Thermal Power (Pe) | N/A W |
| Nominal Diameter | 4.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Fostex FE108SS-HP?
Load Forge's calculated alignment puts Fostex FE108SS-HP in a 4.3 liter vented enclosure tuned to 79.4 Hz, reaching an F3 cutoff of approximately 76.4 Hz.
Can Fostex FE108SS-HP be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 1.9 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 144.7 Hz.
What port dimensions should be used for Fostex FE108SS-HP to avoid port chuffing?
Xmax is not published for Fostex FE108SS-HP, so the port is an empirical estimate: a 5.0 cm diameter with a length of 18.1 cm (area at least 12 in² per ft³ of net volume). Check the air velocity at your power level in Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
Embed this design card on DIYAudio, AVSForum, Reddit, or Facebook. It shows the calculated F3, MOL (when the power rating is published) and box parameters.
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