Passive Radiator / Folded Port

SICA BP 8/150

Best box: 3.6 L sealed · Fc 154.6 Hz · F3 151.9 Hz

Predicted SPL response of the SICA BP 8/150 in the recommended 3.6 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 672.5 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) 8.2 Liters
Tuning Frequency (Fb) 85.1 Hz
F3 (-3 dB Cutoff) 85.4 Hz
F6 / F10 Extension 75.3 Hz / 65.8 Hz
Port Inner Diameter Ø 42.1 cm
Port Physical Length 672.5 cm
First Pipe Resonance 26.0 Hz
Estimated MOL @ F3 111.7 dB SPL
⚠️ Port feasibility: a straight tube would need 672.5 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) 3.6 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 154.6 Hz
F3 (-3 dB Cutoff) 151.9 Hz
F6 / F10 Extension 115.6 Hz / 87.3 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 74.7 Hz
Total Q (Qts) 0.33
Electrical Q (Qes) 0.363
Mechanical Q (Qms) 3.61
Equivalent Volume (Vas) 13.1 Liters
Diaphragm Area (Sd) 213.8 cm²
DC Resistance (Re) 6.08 Ω
Efficiency Bandwidth Product (EBP) 205.7
Linear Excursion (Xmax) 209.0 mm
Thermal Power (Pe) 150.0 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 BP 8/150?

A simple ported box is not recommended for SICA BP 8/150: the textbook alignment (8.2 liters tuned to 85.1 Hz) needs a 672.5 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 BP 8/150 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 3.6 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 151.9 Hz.

What port dimensions should be used for SICA BP 8/150 to avoid port chuffing?

A straight 42.1 cm port would need 672.5 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 BP 8/150 Enclosure Card
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