Fountek FR89EX
Best box: 1.7 L bass reflex tuned to 84.7 Hz · F3 77.7 Hz
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Comparable 3.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Fountek FR89EX 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 (1.7 L at 80.7 Hz) would need a 49.6 cm port; the recommendation is retuned to 1.7 L at 84.7 Hz so the port can be built.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 1.7 Liters |
| Tuning Frequency (Fb) | 84.7 Hz |
| F3 (-3 dB Cutoff) | 77.7 Hz |
| F6 / F10 Extension | 70.4 Hz / 63.1 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 44.7 cm |
| First Pipe Resonance | 385.0 Hz |
| Estimated MOL @ F3 | 94.6 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 0.87 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 144.6 Hz |
| F3 (-3 dB Cutoff) | 145.2 Hz |
| F6 / F10 Extension | 108.6 Hz / 81.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 97.0 Hz |
| Total Q (Qts) | 0.468 |
| Electrical Q (Qes) | 0.655 |
| Mechanical Q (Qms) | 1.64 |
| Equivalent Volume (Vas) | 1.1 Liters |
| Diaphragm Area (Sd) | 27.3 cm² |
| DC Resistance (Re) | 5.7 Ω |
| Efficiency Bandwidth Product (EBP) | 148.2 |
| Linear Excursion (Xmax) | 5.0 mm |
| Thermal Power (Pe) | 25.0 W |
| Nominal Diameter | 3.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Fountek FR89EX?
Load Forge's calculated alignment puts Fountek FR89EX in a 1.7 liter vented enclosure tuned to 84.7 Hz, reaching an F3 cutoff of approximately 77.7 Hz.
Can Fountek FR89EX be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.87 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 145.2 Hz.
What port dimensions should be used for Fountek FR89EX 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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