Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil
Best box: 8.4 L sealed · Fc 65.1 Hz · F3 54.5 Hz
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Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil 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 222.7 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) | 6.7 Liters |
| Tuning Frequency (Fb) | 39.1 Hz |
| F3 (-3 dB Cutoff) | 56.7 Hz |
| F6 / F10 Extension | 47.1 Hz / 36.2 Hz |
| Port Inner Diameter | Ø 10.0 cm |
| Port Physical Length | 222.7 cm |
| First Pipe Resonance | 77.0 Hz |
| Estimated MOL @ F3 | 107.4 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.75 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.061; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 8.4 Liters |
| System Q (Qtc) | 1.061 (above Butterworth: Qtc cannot fall below Qts (0.75)) |
| System Resonance (Fc) | 65.1 Hz |
| F3 (-3 dB Cutoff) | 54.5 Hz |
| F6 / F10 Extension | 45.2 Hz / 36.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 46.0 Hz |
| Total Q (Qts) | 0.75 |
| Electrical Q (Qes) | 0.989 |
| Mechanical Q (Qms) | 3.1 |
| Equivalent Volume (Vas) | 8.4 Liters |
| Diaphragm Area (Sd) | 200.0 cm² |
| DC Resistance (Re) | 3.9 Ω |
| Efficiency Bandwidth Product (EBP) | 46.5 |
| Linear Excursion (Xmax) | 18.0 mm |
| Thermal Power (Pe) | 400.0 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 Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil?
A simple ported box is not recommended for Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil: the textbook alignment (6.7 liters tuned to 39.1 Hz) needs a 222.7 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 Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 8.4 liters with a Qtc of 1.061 (above Butterworth: Qtc cannot fall below Qts (0.75)), the system exhibits an F3 of 54.5 Hz.
What port dimensions should be used for Dayton Audio UMII8-22 Ultimax II 8" DVC Subwoofer 2 Ohm Per Coil to avoid port chuffing?
A straight 10.0 cm port would need 222.7 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
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