Vented Specialist

HELIX Ci7 W130-S3

Best box: 5.0 L bass reflex tuned to 68.4 Hz · F3 65.1 Hz

Predicted SPL response of the HELIX Ci7 W130-S3 in the recommended 5.0 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: 3.4 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) 5.0 Liters
Tuning Frequency (Fb) 68.4 Hz
F3 (-3 dB Cutoff) 65.1 Hz
F6 / F10 Extension 58.1 Hz / 51.5 Hz
Port Inner Diameter Ø 5.0 cm
Port Physical Length 21.6 cm
First Pipe Resonance 797.0 Hz
Estimated MOL @ F3 108.3 dB SPL
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Recommended Sealed (Acoustic Suspension)

MAX TRANSIENT DAMPING
Net Box Volume (Vb) 2.2 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 123.7 Hz
F3 (-3 dB Cutoff) 125.5 Hz
F6 / F10 Extension 94.8 Hz / 71.5 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 73.0 Hz
Total Q (Qts) 0.41
Electrical Q (Qes) 0.495
Mechanical Q (Qms) 2.38
Equivalent Volume (Vas) 4.3 Liters
Diaphragm Area (Sd) 85.0 cm²
DC Resistance (Re) 2.9 Ω
Efficiency Bandwidth Product (EBP) 147.4
Linear Excursion (Xmax) 3.4 mm
Thermal Power (Pe) N/A 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 Ci7 W130-S3?

Load Forge's calculated alignment puts HELIX Ci7 W130-S3 in a 5.0 liter vented enclosure tuned to 68.4 Hz, reaching an F3 cutoff of approximately 65.1 Hz.

Can HELIX Ci7 W130-S3 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 2.2 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 125.5 Hz.

What port dimensions should be used for HELIX Ci7 W130-S3 to avoid port chuffing?

Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 21.6 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 Ci7 W130-S3 Enclosure Card
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