Passive Radiator / Folded Port

SICA 8 M 1.5 CS

Best box: 0.7 L sealed · Fc 650.5 Hz · F3 526.8 Hz

Predicted SPL response of the SICA 8 M 1.5 CS in the recommended 0.7 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 765.4 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) 1.5 Liters
Tuning Frequency (Fb) 391.0 Hz
F3 (-3 dB Cutoff) 484.5 Hz
F6 / F10 Extension 418.1 Hz / 294.4 Hz
Port Inner Diameter Ø 89.9 cm
Port Physical Length 765.4 cm
First Pipe Resonance 22.0 Hz
Estimated MOL @ F3 124.0 dB SPL
⚠️ Port feasibility: a straight tube would need 765.4 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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Sealed (Acoustic Suspension) — compromise

SUITS INFINITE / OPEN BAFFLE

With Qts 1.82 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 2.574; for a flat response this driver is better used on an infinite (IB) or open baffle.

Net Box Volume (Vb) 0.7 Liters
System Q (Qtc) 2.574 (above Butterworth: Qtc cannot fall below Qts (1.82))
System Resonance (Fc) 650.5 Hz
F3 (-3 dB Cutoff) 526.8 Hz
F6 / F10 Extension 475.4 Hz / 413.1 Hz
Air Spring Linearity High (Zero port compression)
Simulate This Sealed Box in App →

Thiele/Small Parameters

Resonance (Fs) 460.0 Hz
Total Q (Qts) 1.82
Electrical Q (Qes) 2.134
Mechanical Q (Qms) 12.36
Equivalent Volume (Vas) 0.7 Liters
Diaphragm Area (Sd) 213.8 cm²
DC Resistance (Re) 6.0 Ω
Efficiency Bandwidth Product (EBP) 215.5
Linear Excursion (Xmax) 208.0 mm
Thermal Power (Pe) 100.0 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 M 1.5 CS?

A simple ported box is not recommended for SICA 8 M 1.5 CS: the textbook alignment (1.5 liters tuned to 391.0 Hz) needs a 765.4 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 8 M 1.5 CS be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 0.7 liters with a Qtc of 2.574 (above Butterworth: Qtc cannot fall below Qts (1.82)), the system exhibits an F3 of 526.8 Hz.

What port dimensions should be used for SICA 8 M 1.5 CS to avoid port chuffing?

A straight 89.9 cm port would need 765.4 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 8 M 1.5 CS Enclosure Card
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