Coast Buyouts Sharp 1208PB038A Speaker 8 Ohm
Best box: 4.5 L bass reflex tuned to 69.7 Hz · F3 133.8 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Coast Buyouts Sharp 1208PB038A Speaker 8 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 116.2 Hz) would need a 25.5 cm port; the recommendation is retuned to 4.5 L at 69.7 Hz so the port can be built.
- Limited linear excursion (Xmax: 1.0 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) | 4.5 Liters |
| Tuning Frequency (Fb) | 69.7 Hz |
| F3 (-3 dB Cutoff) | 133.8 Hz |
| F6 / F10 Extension | 115.8 Hz / 58.2 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 23.3 cm |
| First Pipe Resonance | 737.0 Hz |
| Estimated MOL @ F3 | 92.1 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.6 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 2.263; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 1.9 Liters |
| System Q (Qtc) | 2.263 (above Butterworth: Qtc cannot fall below Qts (1.60)) |
| System Resonance (Fc) | 193.3 Hz |
| F3 (-3 dB Cutoff) | 160.6 Hz |
| F6 / F10 Extension | 143.7 Hz / 123.7 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 136.7 Hz |
| Total Q (Qts) | 1.6 |
| Electrical Q (Qes) | 2.12 |
| Mechanical Q (Qms) | 6.52 |
| Equivalent Volume (Vas) | 1.9 Liters |
| Diaphragm Area (Sd) | 44.3 cm² |
| DC Resistance (Re) | 7.17 Ω |
| Efficiency Bandwidth Product (EBP) | 64.5 |
| Linear Excursion (Xmax) | 1.0 mm |
| Thermal Power (Pe) | 4.0 W |
| Nominal Diameter | 4.0" |
| 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 Sharp 1208PB038A Speaker 8 Ohm?
Load Forge's calculated alignment puts Coast Buyouts Sharp 1208PB038A Speaker 8 Ohm in a 4.5 liter vented enclosure tuned to 69.7 Hz, reaching an F3 cutoff of approximately 133.8 Hz.
Can Coast Buyouts Sharp 1208PB038A Speaker 8 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 1.9 liters with a Qtc of 2.263 (above Butterworth: Qtc cannot fall below Qts (1.60)), the system exhibits an F3 of 160.6 Hz.
What port dimensions should be used for Coast Buyouts Sharp 1208PB038A Speaker 8 Ohm to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 23.3 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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