JBL MI-15
Best box: 135.9 L bass reflex tuned to 46.8 Hz · F3 60.4 Hz
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Comparable 15.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the JBL MI-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
- Large enclosure volume (135.9 L) requires extensive internal matrix bracing to prevent panel resonance.
- Limited linear excursion (Xmax: 3.05 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) | 135.9 Liters |
| Tuning Frequency (Fb) | 46.8 Hz |
| F3 (-3 dB Cutoff) | 60.4 Hz |
| F6 / F10 Extension | 49.6 Hz / 39.1 Hz |
| Port Inner Diameter | Ø 12.5 cm |
| Port Physical Length | 3.4 cm |
| First Pipe Resonance | 5028.0 Hz |
| Estimated MOL @ F3 | 117.5 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.62 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.877; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 169.9 Liters |
| System Q (Qtc) | 0.877 (above Butterworth) |
| System Resonance (Fc) | 77.8 Hz |
| F3 (-3 dB Cutoff) | 62.4 Hz |
| F6 / F10 Extension | 50.1 Hz / 39.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 55.0 Hz |
| Total Q (Qts) | 0.62 |
| Electrical Q (Qes) | 0.796 |
| Mechanical Q (Qms) | 2.8 |
| Equivalent Volume (Vas) | 169.9 Liters |
| Diaphragm Area (Sd) | 900.0 cm² |
| DC Resistance (Re) | 5.6 Ω |
| Efficiency Bandwidth Product (EBP) | 69.1 |
| Linear Excursion (Xmax) | 3.0 mm |
| Thermal Power (Pe) | 150.0 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 JBL MI-15?
Load Forge's calculated alignment puts JBL MI-15 in a 135.9 liter vented enclosure tuned to 46.8 Hz, reaching an F3 cutoff of approximately 60.4 Hz.
Can JBL MI-15 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 169.9 liters with a Qtc of 0.877 (above Butterworth), the system exhibits an F3 of 62.4 Hz.
What port dimensions should be used for JBL MI-15 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 12.5 cm with a length of 3.4 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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