Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm
Best box: 1.9 L bass reflex tuned to 169.3 Hz · F3 231.0 Hz
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Comparable 3.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm 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 (1.5 L at 188.1 Hz) would need a 7.5 cm port; the recommendation is retuned to 1.9 L at 169.3 Hz so the port can be built.
- Limited linear excursion (Xmax: 0.5 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) | 1.9 Liters |
| Tuning Frequency (Fb) | 169.3 Hz |
| F3 (-3 dB Cutoff) | 231.0 Hz |
| F6 / F10 Extension | 212.0 Hz / 136.1 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 7.2 cm |
| First Pipe Resonance | 2378.0 Hz |
| Estimated MOL @ F3 | 95.0 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 4.029 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 5.698; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 0.48 Liters |
| System Q (Qtc) | 5.698 (above Butterworth: Qtc cannot fall below Qts (4.03)) |
| System Resonance (Fc) | 313.0 Hz |
| F3 (-3 dB Cutoff) | 278.7 Hz |
| F6 / F10 Extension | 262.4 Hz / 239.7 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 221.3 Hz |
| Total Q (Qts) | 4.029 |
| Electrical Q (Qes) | 9.783 |
| Mechanical Q (Qms) | 6.85 |
| Equivalent Volume (Vas) | 0.5 Liters |
| Diaphragm Area (Sd) | 26.9 cm² |
| DC Resistance (Re) | 15.81 Ω |
| Efficiency Bandwidth Product (EBP) | 22.6 |
| Linear Excursion (Xmax) | 0.5 mm |
| Thermal Power (Pe) | 3.0 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 Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm?
Load Forge's calculated alignment puts Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm in a 1.9 liter vented enclosure tuned to 169.3 Hz, reaching an F3 cutoff of approximately 231.0 Hz.
Can Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.48 liters with a Qtc of 5.698 (above Butterworth: Qtc cannot fall below Qts (4.03)), the system exhibits an F3 of 278.7 Hz.
What port dimensions should be used for Coast Buyouts 27JR 3" Full-Range Speaker 16 Ohm to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 7.2 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
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