SB Acoustics SB12CACS25-4 Bass-midwoofer
Best box: 0.05 L sealed · Fc 114.0 Hz · F3 111.6 Hz
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Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the SB Acoustics SB12CACS25-4 Bass-midwoofer 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 61.5 Hz) would need a 187.0 cm port; the recommendation is retuned to 1.5 L at 104.6 Hz so the port can be built.
- Port length (75.3 cm) exceeds a straight internal run; use an elbow bend, slotted vent or 3D folded duct to fit the enclosure.
Textbook Bass Reflex — not recommended (8.2 dB bass hump)
PORT NEEDS ELBOW / 3D| Net Box Volume (Vb) | 1.5 Liters |
| Tuning Frequency (Fb) | 104.6 Hz |
| F3 (-3 dB Cutoff) | 99.0 Hz |
| F6 / F10 Extension | 95.0 Hz / 89.3 Hz |
| Port Inner Diameter | Ø 7.5 cm |
| Port Physical Length | 75.3 cm |
| First Pipe Resonance | 228.0 Hz |
| Estimated MOL @ F3 | 94.2 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 0.05 Liters |
| System Q (Qtc) | 0.693 (Butterworth) |
| System Resonance (Fc) | 114.0 Hz |
| F3 (-3 dB Cutoff) | 111.6 Hz |
| F6 / F10 Extension | 85.1 Hz / 64.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 51.0 Hz |
| Total Q (Qts) | 0.31 |
| Electrical Q (Qes) | 0.331 |
| Mechanical Q (Qms) | 4.89 |
| Equivalent Volume (Vas) | 0.2 Liters |
| Diaphragm Area (Sd) | 220.0 cm² |
| DC Resistance (Re) | 3.1 Ω |
| Efficiency Bandwidth Product (EBP) | 154.1 |
| Linear Excursion (Xmax) | 5.0 mm |
| Thermal Power (Pe) | 30.0 W |
| Nominal Diameter | 8.0" |
| 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 SB12CACS25-4 Bass-midwoofer?
A simple ported box is not recommended for SB Acoustics SB12CACS25-4 Bass-midwoofer: the textbook alignment (1.5 liters tuned to 104.6 Hz) needs a 75.3 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 SB Acoustics SB12CACS25-4 Bass-midwoofer be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.05 liters with a Qtc of 0.693 (Butterworth), the system exhibits an F3 of 111.6 Hz.
What port dimensions should be used for SB Acoustics SB12CACS25-4 Bass-midwoofer to avoid port chuffing?
A straight 7.5 cm port would need 75.3 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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