Eminence Alpha-15A 15" Driver
Best box: 259.9 L sealed · Fc 58.0 Hz · F3 44.9 Hz
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Comparable 15.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Eminence Alpha-15A 15" Driver 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 (208.0 L) requires extensive internal matrix bracing to prevent panel resonance.
- Limited linear excursion (Xmax: 3.8 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.
Textbook Bass Reflex — not recommended (6.0 dB bass hump)
PORT BUILDABLE| Net Box Volume (Vb) | 208.0 Liters |
| Tuning Frequency (Fb) | 34.9 Hz |
| F3 (-3 dB Cutoff) | 52.2 Hz |
| F6 / F10 Extension | 46.0 Hz / 38.1 Hz |
| Port Inner Diameter | Ø 10.0 cm |
| Port Physical Length | 2.1 cm |
| First Pipe Resonance | 8028.0 Hz |
| Estimated MOL @ F3 | 115.4 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.26 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.782; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 259.9 Liters |
| System Q (Qtc) | 1.782 (above Butterworth: Qtc cannot fall below Qts (1.26)) |
| System Resonance (Fc) | 58.0 Hz |
| F3 (-3 dB Cutoff) | 44.9 Hz |
| F6 / F10 Extension | 39.4 Hz / 33.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 41.0 Hz |
| Total Q (Qts) | 1.26 |
| Electrical Q (Qes) | 1.526 |
| Mechanical Q (Qms) | 7.23 |
| Equivalent Volume (Vas) | 259.9 Liters |
| Diaphragm Area (Sd) | 856.3 cm² |
| DC Resistance (Re) | 5.88 Ω |
| Efficiency Bandwidth Product (EBP) | 26.9 |
| Linear Excursion (Xmax) | 3.8 mm |
| Thermal Power (Pe) | 220.0 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 Eminence Alpha-15A 15" Driver?
A simple ported box is not recommended for Eminence Alpha-15A 15" Driver: the textbook alignment (208.0 liters tuned to 34.9 Hz) needs a 2.1 cm port, and no nearby retune stays buildable without a bass hump. A sealed box, a passive radiator or a folded duct is the practical choice.
Can Eminence Alpha-15A 15" Driver be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 259.9 liters with a Qtc of 1.782 (above Butterworth: Qtc cannot fall below Qts (1.26)), the system exhibits an F3 of 44.9 Hz.
What port dimensions should be used for Eminence Alpha-15A 15" Driver to avoid port chuffing?
A straight 10.0 cm port would need 2.1 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
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