Fi Car Audio Alpha Series 15
Best box: 91.5 L bass reflex tuned to 32.9 Hz · F3 30.9 Hz
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Comparable 15.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Fi Car Audio Alpha Series 15 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
- The textbook alignment (91.5 L at 26.3 Hz) would need a 73.0 cm port; the recommendation is retuned to 91.5 L at 32.9 Hz so the port can be built.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 91.5 Liters |
| Tuning Frequency (Fb) | 32.9 Hz |
| F3 (-3 dB Cutoff) | 30.9 Hz |
| F6 / F10 Extension | 27.7 Hz / 24.6 Hz |
| Port Inner Diameter | Ø 15.0 cm |
| Port Physical Length | 42.8 cm |
| First Pipe Resonance | 402.0 Hz |
| Estimated MOL @ F3 | 117.3 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 71.9 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 46.4 Hz |
| F3 (-3 dB Cutoff) | 46.3 Hz |
| F6 / F10 Extension | 35.0 Hz / 26.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 34.7 Hz |
| Total Q (Qts) | 0.52 |
| Electrical Q (Qes) | 0.556 |
| Mechanical Q (Qms) | 8.1 |
| Equivalent Volume (Vas) | 61.0 Liters |
| Diaphragm Area (Sd) | 810.0 cm² |
| DC Resistance (Re) | 0.8 Ω |
| Efficiency Bandwidth Product (EBP) | 62.4 |
| Linear Excursion (Xmax) | 17.0 mm |
| Thermal Power (Pe) | 1000.0 W |
| Nominal Diameter | 15.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Fi Car Audio Alpha Series 15?
Load Forge's calculated alignment puts Fi Car Audio Alpha Series 15 in a 91.5 liter vented enclosure tuned to 32.9 Hz, reaching an F3 cutoff of approximately 30.9 Hz.
Can Fi Car Audio Alpha Series 15 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 71.9 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 46.3 Hz.
What port dimensions should be used for Fi Car Audio Alpha Series 15 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 15.0 cm with a length of 42.8 cm is suggested; check the port air velocity at your drive level in the 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.
Not sure if Alpha Series 15 fits your physical space?
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