12" Dual Sealed
Dayton Audio UMII12-22 Ultimax II 12" DVC Subwoofer 2 Ohms Per Coil
181 L net · F3 40 Hz
$19.99 View plan →
Ready-to-build plan
Dayton Audio UMII12-22 Ultimax II 12" DVC Subwoofer 2 Ohms Per Coil Sealed Subwoofer Enclosure Plan with DXF Cut Files + 3D Model
Sealed enclosure plan for the Dayton Audio UMII12-22 Ultimax II 12" DVC Subwoofer 2 Ohms Per Coil: 91 L net, finished box 451 × 451 × 653 mm (W × H × D), Fc 40 Hz, F3 40 Hz. Whole-millimetre DXF cut files + STEP/STL 3D + cut list + predicted response.
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What it will sound like
No guesswork on the sound. This box is engineered to a defined sealed alignment (Qtc 0.71), and the chart below is its predicted frequency response: a maximally flat (Butterworth) roll-off with usable output down to F3 40 Hz and the tight, accurate transient response sealed enclosures are loved for. Build it to the plan and this is what you can expect to measure.
40 Hz
Extension (F3)
40 Hz
Tuning (Fc)
0.71
System Q (Qtc)
91 L
Net volume
114 dB
Max output
85 dB
Sensitivity
What you get
- +Per-panel DXF cut files + a nested cut sheet for an efficient single-board cut
- +Full-size 1:1 print-and-tape A4 templates (PDF) so you can build it accurately with no CNC
- +STEP + STL 3D models so you can preview the exact box before you cut
- +Printable cut list (CSV) with every panel + the driver cutout
- +Separate grille cut file (DXF) + its own 1:1 A4 template, so you can cut the grille from a sheet of perforated mesh metal
- +Recessed-hardware cut-outs built into the panels (2 side-handle recesses and the Speakon connector recess), centred and gasket-sealed, with the mounting bolts marked
- +Predicted-performance charts (response, max SPL, excursion, impedance)
- +Full internal & external dimensions
- +Stacking system: marked foot positions + top alignment pockets with sealed backing plates, so identical boxes stack and self-locate (feet not included)
Inside the plan
Bracing that anyone can build (drill or CNC)
Inside, an interlocking egg-crate of window braces locks together with half-lap joints and glues to all six panels, stiffening the box and pushing its panel resonances well above the bass it plays. To stay rigid but acoustically open, every brace is lightened with a grid of **round holes sized to standard hole-saw diameters** (around 32 to 76 mm). That means you can bore them with cheap, off-the-shelf bits from any hardware store, in a fraction of the time it takes to jigsaw square windows out, and round holes are stronger because there are no sharp corners to crack. Prefer a CNC? The exact same holes are already in the DXF cut files, so the machine cuts them along with the panel outline in one pass. Either way the 1:1 paper templates mark every hole centre for you, and the driver, handle and amplifier/connector clearances are carved into the braces and verified in 3D so nothing ever fouls.
Two ways to cut every part
Print & tape — no CNC needed
No CNC, no laser cutter, no problem. Every panel and brace also comes as a full-size 1:1 PDF, tiled across ordinary A4 paper. Print at 100%, butt the full sheets together edge-to-edge and tape them on the back (no trimming, no guesswork), then lay the template on your board, trace the lines and cut with a jigsaw or router. Every sheet has a printed 100 mm ruler so you can confirm the scale is spot-on before you cut, and each part comes with a one-page map showing exactly how its sheets line up. Got a CNC? Feed it the DXF files instead, and either way you build the very same box.
Or send it straight to a CNC
Every panel, brace and the grille ship as whole-millimetre DXF files, plus a nested cut sheet that arranges all the parts on a single board for an efficient, low-waste cut. Load the DXF into your CAM software (or hand it to a cutting service) and the machine cuts every outline, the driver cutout and the round brace holes in one pass — no measuring, no setup drawings, identical to the box in the 3D model.
Design specs
| Driver | Dayton Audio UMII12-22 Ultimax II 12" DVC Subwoofer 2 Ohms Per Coil |
|---|---|
| Alignment | Sealed, Qtc 0.71 |
| Net volume | 91 L |
| Tuning | Fc 40 Hz · F3 40 Hz |
| External (W×H×D) | 451 × 451 × 653 mm |
| Material | 18 mm MDF/plywood |
| Max SPL | 114 dB @ 300 Hz (800 W) |
| Sensitivity | 85 dB @ 1 W / 1 m |
| Array coupling | +6 dB up to 191 Hz when arrayed (451 mm centres) |
| Handles | 2x Penn Elcom H1105 recessed steel side handles (1 per side) |
| Connectors | Penn Elcom D0604 recessed back panel (2x Speakon) |
| Grille | 2 mm inset grille on a 29 mm front lip, 8 support blocks (perforated steel or mesh, customer supplied) |
| Stacking | 4x Adam Hall 4907TP rubber feet; 40 mm top pockets self-locate stacked boxes (panels carry the load, pockets sealed by glued backing plates) |
| Alignment | Max-flat (Qtc 0.707) |
| Group delay | 5.6 ms @ Fc |
| Driver T/S | Fs 31.69 Hz · Qts 0.5617 · Vas 52.81 L · Xmax 22 mm · Pe 800 W |
Hardware you'll need
The plan is cut to fit these exact parts, so order these and they drop straight in (every recess is built around their real measured dimensions):
- Penn Elcom H1105 — 2 recessed steel side handles (sealing gasket included with the handle); the 1-per-side recesses are cut to this exact handle
- Penn Elcom D0604 — recessed back-panel dish for 2x Speakon connectors; the cut-out is sized to this exact dish
- Adam Hall 4907TP — 4x rubber stacking feet (38 mm dia); the foot marks and 40 mm top pockets are sized for these
- Perforated mesh metal sheet — any perforated steel or aluminium sheet; cut the grille to size from the included grille DXF / 1:1 A4 template
- Dayton Audio UMII12-22 Ultimax II 12" DVC Subwoofer 2 Ohms Per Coil — the subwoofer driver itself (not included)
Build it this weekend
Instant download: DXF cut files, 1:1 print templates, 3D models, cut list and predicted response.
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