SB Acoustics 5×8″ SB15SFCR39-4 / Paper
Best box: 28.4 L bass reflex tuned to 36.3 Hz · F3 37.6 Hz
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Comparable 7.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the SB Acoustics 5×8″ SB15SFCR39-4 / Paper does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 28.4 Liters |
| Tuning Frequency (Fb) | 36.3 Hz |
| F3 (-3 dB Cutoff) | 37.6 Hz |
| F6 / F10 Extension | 32.8 Hz / 28.5 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 12.2 cm |
| First Pipe Resonance | 1415.0 Hz |
| Estimated MOL @ F3 | 103.9 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 12.9 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 66.8 Hz |
| F3 (-3 dB Cutoff) | 68.2 Hz |
| F6 / F10 Extension | 51.3 Hz / 38.6 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 31.0 Hz |
| Total Q (Qts) | 0.32 |
| Electrical Q (Qes) | 0.336 |
| Mechanical Q (Qms) | 6.57 |
| Equivalent Volume (Vas) | 49.9 Liters |
| Diaphragm Area (Sd) | 178.0 cm² |
| DC Resistance (Re) | 3.5 Ω |
| Efficiency Bandwidth Product (EBP) | 92.2 |
| Linear Excursion (Xmax) | 5.5 mm |
| Thermal Power (Pe) | 80.0 W |
| Nominal Diameter | 7.5" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for SB Acoustics 5×8″ SB15SFCR39-4 / Paper?
Load Forge's calculated alignment puts SB Acoustics 5×8″ SB15SFCR39-4 / Paper in a 28.4 liter vented enclosure tuned to 36.3 Hz, reaching an F3 cutoff of approximately 37.6 Hz.
Can SB Acoustics 5×8″ SB15SFCR39-4 / Paper be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 12.9 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 68.2 Hz.
What port dimensions should be used for SB Acoustics 5×8″ SB15SFCR39-4 / Paper to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 12.2 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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