Vented Specialist

Eighteen Sound 18NLW9601

Best box: 43.1 L bass reflex tuned to 75.3 Hz · F3 76.2 Hz

Predicted SPL response of the Eighteen Sound 18NLW9601 in the recommended 43.1 L bass reflex box versus the alternative — open it in the simulator Open and tweak this box live ↗

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Estimated retail 697.00 EUR · Check price & availability ↗

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⚠️ Engineering Notice for Builders

  • The textbook alignment (43.1 L at 50.2 Hz) would need a 77.3 cm port; the recommendation is retuned to 43.1 L at 75.3 Hz so the port can be built.

Recommended Bass Reflex (Vented)

PORT BUILDABLE
Net Box Volume (Vb) 43.1 Liters
Tuning Frequency (Fb) 75.3 Hz
F3 (-3 dB Cutoff) 76.2 Hz
F6 / F10 Extension 68.6 Hz / 60.4 Hz
Port Inner Diameter Ø 25.2 cm
Port Physical Length 43.2 cm
First Pipe Resonance 399.0 Hz
Estimated MOL @ F3 128.4 dB SPL
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Recommended Sealed (Acoustic Suspension)

MAX TRANSIENT DAMPING
Net Box Volume (Vb) 20.6 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 91.8 Hz
F3 (-3 dB Cutoff) 103.6 Hz
F6 / F10 Extension 79.8 Hz / 60.9 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 38.0 Hz
Total Q (Qts) 0.28
Electrical Q (Qes) 0.294
Mechanical Q (Qms) 6.0
Equivalent Volume (Vas) 111.0 Liters
Diaphragm Area (Sd) 1295.0 cm²
DC Resistance (Re) 2.7 Ω
Efficiency Bandwidth Product (EBP) 129.4
Linear Excursion (Xmax) 14.0 mm
Thermal Power (Pe) 1800.0 W
Nominal Diameter 18.0"
Catalog Source Load Forge catalog (manufacturer datasheets and retailer listings)

Frequently Asked Questions

What is the recommended ported (bass reflex) box volume for Eighteen Sound 18NLW9601?

Load Forge's calculated alignment puts Eighteen Sound 18NLW9601 in a 43.1 liter vented enclosure tuned to 75.3 Hz, reaching an F3 cutoff of approximately 76.2 Hz.

Can Eighteen Sound 18NLW9601 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 20.6 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 103.6 Hz.

What port dimensions should be used for Eighteen Sound 18NLW9601 to avoid port chuffing?

Sized from cone displacement (Sd × Xmax), a minimum port diameter of 25.2 cm with a length of 43.2 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.

Eighteen Sound 18NLW9601 Enclosure Card
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