Vented Specialist

HELIX Ci3 W130-S3

Best box: 3.7 L bass reflex tuned to 75.6 Hz · F3 110.3 Hz

Predicted SPL response of the HELIX Ci3 W130-S3 in the recommended 3.7 L bass reflex box versus the alternative — open it in the simulator Open and tweak this box live ↗

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⚠️ Engineering Notice for Builders

  • Limited linear excursion (Xmax: 3.2 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.

Recommended Bass Reflex (Vented)

PORT BUILDABLE
Net Box Volume (Vb) 3.7 Liters
Tuning Frequency (Fb) 75.6 Hz
F3 (-3 dB Cutoff) 110.3 Hz
F6 / F10 Extension 92.0 Hz / 71.1 Hz
Port Inner Diameter Ø 5.0 cm
Port Physical Length 24.3 cm
First Pipe Resonance 709.0 Hz
Estimated MOL @ F3 107.0 dB SPL
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Sealed (Acoustic Suspension) — compromise

SUITS INFINITE / OPEN BAFFLE

With Qts 0.74 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.047; for a flat response this driver is better used on an infinite (IB) or open baffle.

Net Box Volume (Vb) 4.6 Liters
System Q (Qtc) 1.047 (above Butterworth: Qtc cannot fall below Qts (0.74))
System Resonance (Fc) 125.9 Hz
F3 (-3 dB Cutoff) 105.3 Hz
F6 / F10 Extension 87.4 Hz / 70.4 Hz
Air Spring Linearity High (Zero port compression)
Simulate This Sealed Box in App →

Thiele/Small Parameters

Resonance (Fs) 89.0 Hz
Total Q (Qts) 0.74
Electrical Q (Qes) 0.971
Mechanical Q (Qms) 3.11
Equivalent Volume (Vas) 4.6 Liters
Diaphragm Area (Sd) 98.0 cm²
DC Resistance (Re) 3.1 Ω
Efficiency Bandwidth Product (EBP) 91.7
Linear Excursion (Xmax) 3.2 mm
Thermal Power (Pe) 90.0 W
Nominal Diameter 5.0"
Catalog Source Load Forge catalog (manufacturer datasheets and retailer listings)

Frequently Asked Questions

What is the recommended ported (bass reflex) box volume for HELIX Ci3 W130-S3?

Load Forge's calculated alignment puts HELIX Ci3 W130-S3 in a 3.7 liter vented enclosure tuned to 75.6 Hz, reaching an F3 cutoff of approximately 110.3 Hz.

Can HELIX Ci3 W130-S3 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 4.6 liters with a Qtc of 1.047 (above Butterworth: Qtc cannot fall below Qts (0.74)), the system exhibits an F3 of 105.3 Hz.

What port dimensions should be used for HELIX Ci3 W130-S3 to avoid port chuffing?

Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 24.3 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.

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.

HELIX Ci3 W130-S3 Enclosure Card
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