Passive Radiator / Folded Port

SICA 3.5 H 1 CS

Best box: 2.3 L sealed · Fc 111.7 Hz · F3 113.0 Hz

Predicted SPL response of the SICA 3.5 H 1 CS in the recommended 2.3 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 211.1 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) 2.7 Liters
Tuning Frequency (Fb) 63.2 Hz
F3 (-3 dB Cutoff) 68.7 Hz
F6 / F10 Extension 54.9 Hz / 47.9 Hz
Port Inner Diameter Ø 10.0 cm
Port Physical Length 211.1 cm
First Pipe Resonance 81.0 Hz
Estimated MOL @ F3 98.3 dB SPL
⚠️ Port feasibility: a straight tube would need 211.1 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) 2.3 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 111.7 Hz
F3 (-3 dB Cutoff) 113.0 Hz
F6 / F10 Extension 85.3 Hz / 64.4 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 85.0 Hz
Total Q (Qts) 0.53
Electrical Q (Qes) 0.574
Mechanical Q (Qms) 6.95
Equivalent Volume (Vas) 1.8 Liters
Diaphragm Area (Sd) 38.5 cm²
DC Resistance (Re) 6.1 Ω
Efficiency Bandwidth Product (EBP) 148.1
Linear Excursion (Xmax) 88.0 mm
Thermal Power (Pe) 45.0 W
Nominal Diameter 3.5"
Catalog Source Load Forge catalog (manufacturer datasheets and retailer listings)

Frequently Asked Questions

What is the recommended ported (bass reflex) box volume for SICA 3.5 H 1 CS?

A simple ported box is not recommended for SICA 3.5 H 1 CS: the textbook alignment (2.7 liters tuned to 63.2 Hz) needs a 211.1 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 3.5 H 1 CS be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 2.3 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 113.0 Hz.

What port dimensions should be used for SICA 3.5 H 1 CS to avoid port chuffing?

A straight 10.0 cm port would need 211.1 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 3.5 H 1 CS Enclosure Card
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