Vented Specialist

DB Drive QPSM8V4

Best box: 18.3 L bass reflex tuned to 71.2 Hz · F3 76.4 Hz

Predicted SPL response of the DB Drive QPSM8V4 in the recommended 18.3 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

  • Xmax is not published, so the port size is an empirical estimate (area ≥ 12 in² per ft³ of net volume, minimum by driver size), not a displacement calculation. Check air velocity in Load Forge Studio.

Recommended Bass Reflex (Vented)

PORT BUILDABLE
Net Box Volume (Vb) 18.3 Liters
Tuning Frequency (Fb) 71.2 Hz
F3 (-3 dB Cutoff) 76.4 Hz
F6 / F10 Extension 61.7 Hz / 53.8 Hz
Port Inner Diameter ESTIMATED Ø 10.0 cm
Port Physical Length 18.2 cm
First Pipe Resonance 944.0 Hz
Estimated MOL @ F3 114.2 dB SPL
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Recommended Sealed (Acoustic Suspension)

MAX TRANSIENT DAMPING
Net Box Volume (Vb) 17.1 Liters
System Q (Qtc) 0.707 (Butterworth)
System Resonance (Fc) 120.8 Hz
F3 (-3 dB Cutoff) 122.4 Hz
F6 / F10 Extension 92.5 Hz / 69.9 Hz
Air Spring Linearity High (Zero port compression)
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Thiele/Small Parameters

Resonance (Fs) 97.3 Hz
Total Q (Qts) 0.54
Electrical Q (Qes) 0.631
Mechanical Q (Qms) 3.73
Equivalent Volume (Vas) 12.2 Liters
Diaphragm Area (Sd) 220.0 cm²
DC Resistance (Re) 3.2 Ω
Efficiency Bandwidth Product (EBP) 154.1
Linear Excursion (Xmax) N/A mm
Thermal Power (Pe) 200.0 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 DB Drive QPSM8V4?

Load Forge's calculated alignment puts DB Drive QPSM8V4 in a 18.3 liter vented enclosure tuned to 71.2 Hz, reaching an F3 cutoff of approximately 76.4 Hz.

Can DB Drive QPSM8V4 be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 17.1 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 122.4 Hz.

What port dimensions should be used for DB Drive QPSM8V4 to avoid port chuffing?

Xmax is not published for DB Drive QPSM8V4, so the port is an empirical estimate: a 10.0 cm diameter with a length of 18.2 cm (area at least 12 in² per ft³ of net volume). Check the air velocity at your power level in 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.

DB Drive QPSM8V4 Enclosure Card
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