Fountek FR88EX
Best box: 2.7 L bass reflex tuned to 67.2 Hz · F3 69.1 Hz
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Comparable 3.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Fountek FR88EX 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 (2.7 L at 61.1 Hz) would need a 54.8 cm port; the recommendation is retuned to 2.7 L at 67.2 Hz so the port can be built.
- Limited linear excursion (Xmax: 2.0 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 2.7 Liters |
| Tuning Frequency (Fb) | 67.2 Hz |
| F3 (-3 dB Cutoff) | 69.1 Hz |
| F6 / F10 Extension | 57.6 Hz / 50.4 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 44.7 cm |
| First Pipe Resonance | 385.0 Hz |
| Estimated MOL @ F3 | 91.7 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 2.8 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 107.6 Hz |
| F3 (-3 dB Cutoff) | 108.9 Hz |
| F6 / F10 Extension | 82.4 Hz / 62.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 85.0 Hz |
| Total Q (Qts) | 0.55 |
| Electrical Q (Qes) | 0.664 |
| Mechanical Q (Qms) | 3.2 |
| Equivalent Volume (Vas) | 1.8 Liters |
| Diaphragm Area (Sd) | 38.0 cm² |
| DC Resistance (Re) | 4.0 Ω |
| Efficiency Bandwidth Product (EBP) | 128.0 |
| Linear Excursion (Xmax) | 2.0 mm |
| Thermal Power (Pe) | 10.0 W |
| Nominal Diameter | 3.5" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Fountek FR88EX?
Load Forge's calculated alignment puts Fountek FR88EX in a 2.7 liter vented enclosure tuned to 67.2 Hz, reaching an F3 cutoff of approximately 69.1 Hz.
Can Fountek FR88EX be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 2.8 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 108.9 Hz.
What port dimensions should be used for Fountek FR88EX to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 44.7 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.
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