Kartesian Sub120_vHP
Best box: 2.1 L bass reflex tuned to 54.4 Hz · F3 54.1 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Kartesian Sub120_vHP does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- The textbook alignment (2.1 L at 51.8 Hz) would need a 100.9 cm port; the recommendation is retuned to 2.1 L at 54.4 Hz so the port can be built.
- Port length (91.1 cm) exceeds a straight internal run; use an elbow bend, slotted vent or 3D folded duct to fit the enclosure.
Recommended Bass Reflex (Vented)
PORT NEEDS ELBOW / 3D| Net Box Volume (Vb) | 2.1 Liters |
| Tuning Frequency (Fb) | 54.4 Hz |
| F3 (-3 dB Cutoff) | 54.1 Hz |
| F6 / F10 Extension | 47.9 Hz / 42.0 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 91.1 cm |
| First Pipe Resonance | 189.0 Hz |
| Estimated MOL @ F3 | 108.1 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 0.96 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 96.7 Hz |
| F3 (-3 dB Cutoff) | 95.9 Hz |
| F6 / F10 Extension | 72.6 Hz / 54.8 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 45.7 Hz |
| Total Q (Qts) | 0.332 |
| Electrical Q (Qes) | 0.382 |
| Mechanical Q (Qms) | 2.52 |
| Equivalent Volume (Vas) | 3.4 Liters |
| Diaphragm Area (Sd) | 53.3 cm² |
| DC Resistance (Re) | 6.8 Ω |
| Efficiency Bandwidth Product (EBP) | 119.5 |
| Linear Excursion (Xmax) | 6.0 mm |
| Thermal Power (Pe) | N/A W |
| Nominal Diameter | 4.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Kartesian Sub120_vHP?
Load Forge's calculated alignment puts Kartesian Sub120_vHP in a 2.1 liter vented enclosure tuned to 54.4 Hz, reaching an F3 cutoff of approximately 54.1 Hz.
Can Kartesian Sub120_vHP be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.96 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 95.9 Hz.
What port dimensions should be used for Kartesian Sub120_vHP to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 91.1 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.
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