Passive Radiator / Folded Port

SICA BP 12/250

Best box: 18.9 L sealed · Fc 104.9 Hz · F3 102.9 Hz

Predicted SPL response of the SICA BP 12/250 in the recommended 18.9 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 646.3 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) 41.9 Liters
Tuning Frequency (Fb) 58.8 Hz
F3 (-3 dB Cutoff) 58.8 Hz
F6 / F10 Extension 52.1 Hz / 45.5 Hz
Port Inner Diameter Ø 65.3 cm
Port Physical Length 646.3 cm
First Pipe Resonance 27.0 Hz
Estimated MOL @ F3 116.2 dB SPL
⚠️ Port feasibility: a straight tube would need 646.3 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) 18.9 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 104.9 Hz
F3 (-3 dB Cutoff) 102.9 Hz
F6 / F10 Extension 78.3 Hz / 59.2 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 50.2 Hz
Total Q (Qts) 0.32
Electrical Q (Qes) 0.341
Mechanical Q (Qms) 5.14
Equivalent Volume (Vas) 73.5 Liters
Diaphragm Area (Sd) 490.9 cm²
DC Resistance (Re) 6.21 Ω
Efficiency Bandwidth Product (EBP) 147.1
Linear Excursion (Xmax) 318.0 mm
Thermal Power (Pe) 250.0 W
Nominal Diameter 12.0"
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 12/250?

A simple ported box is not recommended for SICA BP 12/250: the textbook alignment (41.9 liters tuned to 58.8 Hz) needs a 646.3 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 BP 12/250 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 18.9 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 102.9 Hz.

What port dimensions should be used for SICA BP 12/250 to avoid port chuffing?

A straight 65.3 cm port would need 646.3 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

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 12/250 Enclosure Card
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