SICA 18 K 4 PL
Best box: 51.8 L sealed · Fc 77.1 Hz · F3 78.2 Hz
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Comparable 18.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the SICA 18 K 4 PL 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
- Straight vent would be 1117.3 cm long: not physically buildable as a simple tube. Use a passive radiator, a folded slot port or model a 3D folded duct in Load Forge Studio.
Textbook Bass Reflex — not recommended
PORT NOT BUILDABLE| Net Box Volume (Vb) | 114.6 Liters |
| Tuning Frequency (Fb) | 43.1 Hz |
| F3 (-3 dB Cutoff) | 43.4 Hz |
| F6 / F10 Extension | 38.4 Hz / 33.5 Hz |
| Port Inner Diameter | Ø 103.8 cm |
| Port Physical Length | 1117.3 cm |
| First Pipe Resonance | 15.0 Hz |
| Estimated MOL @ F3 | 123.4 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 51.8 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 77.1 Hz |
| F3 (-3 dB Cutoff) | 78.2 Hz |
| F6 / F10 Extension | 58.9 Hz / 44.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 36.8 Hz |
| Total Q (Qts) | 0.32 |
| Electrical Q (Qes) | 0.344 |
| Mechanical Q (Qms) | 4.62 |
| Equivalent Volume (Vas) | 201.0 Liters |
| Diaphragm Area (Sd) | 1164.2 cm² |
| DC Resistance (Re) | 6.0 Ω |
| Efficiency Bandwidth Product (EBP) | 107.0 |
| Linear Excursion (Xmax) | 462.0 mm |
| Thermal Power (Pe) | 1200.0 W |
| Nominal Diameter | 18.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for SICA 18 K 4 PL?
A simple ported box is not recommended for SICA 18 K 4 PL: the textbook alignment (114.6 liters tuned to 43.1 Hz) needs a 1117.3 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 SICA 18 K 4 PL be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 51.8 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 78.2 Hz.
What port dimensions should be used for SICA 18 K 4 PL to avoid port chuffing?
A straight 103.8 cm port would need 1117.3 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
Shareable Acoustic Card for Forums & Social Media
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