Passive Radiator / Folded Port

SICA BS 8N/250A

Best box: 5.6 L sealed · Fc 110.0 Hz · F3 109.4 Hz

Predicted SPL response of the SICA BS 8N/250A in the recommended 5.6 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 604.4 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) 12.9 Liters
Tuning Frequency (Fb) 60.6 Hz
F3 (-3 dB Cutoff) 58.8 Hz
F6 / F10 Extension 52.3 Hz / 46.1 Hz
Port Inner Diameter Ø 35.6 cm
Port Physical Length 604.4 cm
First Pipe Resonance 28.0 Hz
Estimated MOL @ F3 111.2 dB SPL
⚠️ Port feasibility: a straight tube would need 604.4 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) 5.6 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 110.0 Hz
F3 (-3 dB Cutoff) 109.4 Hz
F6 / F10 Extension 82.7 Hz / 62.4 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 59.0 Hz
Total Q (Qts) 0.37
Electrical Q (Qes) 0.392
Mechanical Q (Qms) 6.72
Equivalent Volume (Vas) 14.9 Liters
Diaphragm Area (Sd) 213.8 cm²
DC Resistance (Re) 5.5 Ω
Efficiency Bandwidth Product (EBP) 150.7
Linear Excursion (Xmax) 210.0 mm
Thermal Power (Pe) 250.0 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 BS 8N/250A?

A simple ported box is not recommended for SICA BS 8N/250A: the textbook alignment (12.9 liters tuned to 60.6 Hz) needs a 604.4 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 BS 8N/250A be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 5.6 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 109.4 Hz.

What port dimensions should be used for SICA BS 8N/250A to avoid port chuffing?

A straight 35.6 cm port would need 604.4 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 BS 8N/250A Enclosure Card
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