DD Audio 9912C D2
Best box: 7.8 L sealed · Fc 63.1 Hz · F3 64.7 Hz
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Comparable 13.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the DD Audio 9912C D2 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
- Straight vent would be 445.9 cm long: not physically buildable as a simple tube. Use a passive radiator, a folded slot port or model a 3D folded duct in Load Forge Studio.
Textbook Bass Reflex — not recommended
PORT NOT BUILDABLE| Net Box Volume (Vb) | 17.7 Liters |
| Tuning Frequency (Fb) | 34.0 Hz |
| F3 (-3 dB Cutoff) | 34.6 Hz |
| F6 / F10 Extension | 30.3 Hz / 26.4 Hz |
| Port Inner Diameter | Ø 20.0 cm |
| Port Physical Length | 445.9 cm |
| First Pipe Resonance | 39.0 Hz |
| Estimated MOL @ F3 | 116.7 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 7.8 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 63.1 Hz |
| F3 (-3 dB Cutoff) | 64.7 Hz |
| F6 / F10 Extension | 48.7 Hz / 36.6 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 31.6 Hz |
| Total Q (Qts) | 0.352 |
| Electrical Q (Qes) | 0.377 |
| Mechanical Q (Qms) | 5.4 |
| Equivalent Volume (Vas) | 23.6 Liters |
| Diaphragm Area (Sd) | 613.1 cm² |
| DC Resistance (Re) | 1.7 Ω |
| Efficiency Bandwidth Product (EBP) | 84.0 |
| Linear Excursion (Xmax) | 32.0 mm |
| Thermal Power (Pe) | 3200.0 W |
| Nominal Diameter | 13.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for DD Audio 9912C D2?
A simple ported box is not recommended for DD Audio 9912C D2: the textbook alignment (17.7 liters tuned to 34.0 Hz) needs a 445.9 cm port, and no nearby retune stays buildable without a bass hump. A sealed box, a passive radiator or a folded duct is the practical choice.
Can DD Audio 9912C D2 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 7.8 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 64.7 Hz.
What port dimensions should be used for DD Audio 9912C D2 to avoid port chuffing?
A straight 20.0 cm port would need 445.9 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
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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