Passive Radiator / Folded Port

SICA 15 PNS 4

Best box: 37.8 L sealed · Fc 72.5 Hz · F3 73.9 Hz

Predicted SPL response of the SICA 15 PNS 4 in the recommended 37.8 L sealed box versus the alternative — open it in the simulator Open and tweak this box live ↗

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⚠️ Engineering Notice for Builders

  • Straight vent would be 996.5 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) 85.7 Liters
Tuning Frequency (Fb) 40.3 Hz
F3 (-3 dB Cutoff) 39.9 Hz
F6 / F10 Extension 35.3 Hz / 31.0 Hz
Port Inner Diameter Ø 78.9 cm
Port Physical Length 996.5 cm
First Pipe Resonance 17.0 Hz
Estimated MOL @ F3 121.0 dB SPL
⚠️ Port feasibility: a straight tube would need 996.5 cm and cannot fit in a practical cabinet, and no nearby retune stays buildable without a bass hump. Prefer the sealed alignment, a passive radiator, or a 3D folded duct in Load Forge Studio.
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Recommended Sealed (Acoustic Suspension)

MAX TRANSIENT DAMPING
Net Box Volume (Vb) 37.8 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 72.5 Hz
F3 (-3 dB Cutoff) 73.9 Hz
F6 / F10 Extension 55.6 Hz / 41.9 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 37.3 Hz
Total Q (Qts) 0.35
Electrical Q (Qes) 0.375
Mechanical Q (Qms) 5.21
Equivalent Volume (Vas) 116.3 Liters
Diaphragm Area (Sd) 855.3 cm²
DC Resistance (Re) 5.1 Ω
Efficiency Bandwidth Product (EBP) 99.4
Linear Excursion (Xmax) 388.0 mm
Thermal Power (Pe) 1200.0 W
Nominal Diameter 15.0"
Catalog Source Load Forge catalog (manufacturer datasheets and retailer listings)

Frequently Asked Questions

What is the recommended ported (bass reflex) box volume for SICA 15 PNS 4?

A simple ported box is not recommended for SICA 15 PNS 4: the textbook alignment (85.7 liters tuned to 40.3 Hz) needs a 996.5 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 15 PNS 4 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 37.8 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 73.9 Hz.

What port dimensions should be used for SICA 15 PNS 4 to avoid port chuffing?

A straight 78.9 cm port would need 996.5 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

Embed this design card on DIYAudio, AVSForum, Reddit, or Facebook. It shows the calculated F3, MOL (when the power rating is published) and box parameters.

SICA 15 PNS 4 Enclosure Card
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