Passive Radiator / Folded Port

SICA 8 Fe 2 CP

Best box: 4.4 L sealed · Fc 142.9 Hz · F3 139.6 Hz

Predicted SPL response of the SICA 8 Fe 2 CP in the recommended 4.4 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 623.8 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) 9.6 Liters
Tuning Frequency (Fb) 78.5 Hz
F3 (-3 dB Cutoff) 79.6 Hz
F6 / F10 Extension 70.0 Hz / 61.1 Hz
Port Inner Diameter Ø 40.5 cm
Port Physical Length 623.8 cm
First Pipe Resonance 28.0 Hz
Estimated MOL @ F3 112.5 dB SPL
⚠️ Port feasibility: a straight tube would need 623.8 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) 4.4 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 142.9 Hz
F3 (-3 dB Cutoff) 139.6 Hz
F6 / F10 Extension 106.3 Hz / 80.3 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 67.0 Hz
Total Q (Qts) 0.32
Electrical Q (Qes) 0.373
Mechanical Q (Qms) 2.27
Equivalent Volume (Vas) 16.9 Liters
Diaphragm Area (Sd) 213.8 cm²
DC Resistance (Re) 6.1 Ω
Efficiency Bandwidth Product (EBP) 179.9
Linear Excursion (Xmax) 210.0 mm
Thermal Power (Pe) 200.0 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 SICA 8 Fe 2 CP?

A simple ported box is not recommended for SICA 8 Fe 2 CP: the textbook alignment (9.6 liters tuned to 78.5 Hz) needs a 623.8 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 8 Fe 2 CP be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 4.4 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 139.6 Hz.

What port dimensions should be used for SICA 8 Fe 2 CP to avoid port chuffing?

A straight 40.5 cm port would need 623.8 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 8 Fe 2 CP Enclosure Card
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