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Proline X PO 12-S DFW W3 sealed down-fire wide enclosure for the JL Audio 12W3v3, 41 inches wide by 8.1875 inches tall, feet add 1.75 inches of height.
Proline X PO 12-S DFW W3 sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 8.1875 inches tall by 14 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 12" Enclosure JL Audio 12W3v3 · Single 12" Sealed enclosure

Net volume
1.573 cu ft after the brace and 0.071 cu ft displacement
Max mounting depth
6.65 Inches / 169mm (JL Audio Spec)
Cutout
11.0625 Inches / 281mm (JL Audio Spec)
External dimensions
41 in W × 8.1875 in in the down fire position H × 14 in D
Front baffle
1.5 in double baffle, outer layer machined as a flush recess
Buy at Audio IntensityFactory-direct, ships from Tullahoma
JL Audio 12W3v3Buy at Audio Intensity
  • Alignment: 1.573 cu ft net. 12W3v3-4: Qtc 0.744, Fc 44.8 Hz, F3 42.7 Hz. 12W3v3-2: Qtc 0.834, Fc 46.7 Hz, F3 40.6 Hz
  • Down Fire Wide: 41"W x 14"D x 8.1875"H in down fire position, excludes standoffs, square corners
  • Versus the standard 30 x 15: 8.3125 in tall and 1.23 cu ft net there, 8.1875 in tall and 1.573 cu ft net here
  • Driver: JL Audio 12W3v3-4 (SVC 4Ω), 500W RMS, 13.0mm Xmax, 26.72 Hz Fs, 80.54 L Vas (-2: 27.97 Hz Fs, 0.500 Qts, 79.47 L Vas), 6.65" mounting depth
  • Standoffs: Included, 1.75 in, shipped uninstalled. Installed height 9.9375 in

Spec of record

Technical specifications

SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverJL Audio 12W3v3-4. Direct fit
Enclosure TypeSealed, down fire, floor coupled
Intended FitmentSpaces where height or depth is the limit and 41 in of run is available
Chamber ConfigurationSingle chamber, windowed U-brace, one side-mounted terminal cup
External Width41 in
External Depth14 in
External Height8.1875 in in the down fire position, excludes standoffs
Installed Height9.9375 in including the 1.75 in standoffs
Internal Volume, Gross1.65 cu ft
Internal Volume, Net1.573 cu ft after the brace and 0.071 cu ft displacement
Height Set ByDriver clearance: 0.75 in above the 6.65 in motor
Alignment12W3v3-4: Qtc 0.744, Fc 44.8 Hz, F3 42.7 Hz. 12W3v3-2: Qtc 0.834, Fc 46.7 Hz, F3 40.6 Hz. Anechoic
Comparison, Standard 30 x 158.3125 in tall, 1.23 cu ft net. Wide format is 8.1875 in tall with 1.573 cu ft net
Driver Fs26.72 Hz (-4) / 27.97 Hz (-2)
Driver Qts0.444 (-4) / 0.500 (-2)
Driver Qes / Qms0.472 / 7.572
Driver Vas80.54 Liters (-4) / 79.47 Liters (-2), Largest In The Down Fire Line
Driver Sd80.6 sq in / 0.0520 m²
Driver Xmax (One-Way Linear)13.0mm / 0.510 in
Driver Displacement0.071 Cubic Feet / 2.01 L (Published by JL Audio)
Driver Sensitivity87.15 dB (1W/1m)
Driver Power Handling500 Watts RMS Continuous
Recommended Amplifier Power150 to 500 Watts RMS (JL Audio Spec)
Driver ConeMineral-Filled Polypropylene | Rubber Surround
Driver TechnologyDynamic Motor Analysis (DMA) | Elevated Frame Cooling
Mounting Depth Required6.65 Inches / 169mm (JL Audio Spec)
Cutout Diameter11.0625 Inches / 281mm (JL Audio Spec)
Driver Overall Diameter12.5 Inches / 318mm (JL Audio Spec)
Voice Coil ConfigurationSingle Voice Coil | 4 Ohm Nominal
MaterialLangboard Elite 3/4 in MDF
ConstructionShopSabre CNC, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in double baffle, outer layer machined as a flush recess
Internal BracingWindowed U-brace, dadoed to the shell
Corner ProfileSquare, Down Fire series standard
Driver Mounting8/32 threaded inserts with stainless machine screws
Terminal CupOne Proline X ABS and carbon fiber composite, side mounted, pre-wired 12 gauge OFC
StandoffsIncluded, 1.75 in, shipped uninstalled
DampingLight polyfill wall lining, does not alter acoustic volume
CarpetPlush Black
Bundle OptionsEnclosure only, bring your own JL Audio 12W3v3-4
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.573
cu ft per chamber
System Qtc
0.74–0.83
sealed
Half power
40.6–42.7
Hz · F3
Xmax at
254
W RMS · no filter
With 25 Hz subsonic
319
W RMS · +26%
Amplifier
150–500
W RMS recommended
This enclosure holds 1.573 cu ft net per chamber. In it the JL Audio 12W3v3-4 runs a system Qtc of 0.74–0.83 with half power at 40.6–42.7 Hz, and the cone reaches its 13.0 mm travel limit at 254 W, below the driver’s 500 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 319 W — +65 W, or 26 percent more power for the same 13.0 mm of travel.

01Is it a sealed driver?

Efficiency bandwidth product places the motor before anything else is decided.

EBP = Fs ÷ Qes = 52.4–56.6
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 -2 52.4 -4 56.6
-2 · EBP 52.4-4 · EBP 56.6
At 52.4–56.6 the 12W3v3-4 sits in the transition band, not the sealed band. That is not a mismatch: a transition motor works in either alignment, and sealed buys a smaller box and a gentler roll-off at the cost of some low-end output. Stage 02 shows what this airspace actually does with it.

02What the box does to it

1.573 cu ft against a 79.5 L Vas.

α = Vas ÷ Vb = 1.78  ·  Fc = Fs√(α+1) = 45–47 Hz  ·  Qtc = 0.74–0.83
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
-2 · Qtc 0.83, Fc 47 Hz, F3 40.6 Hz-4 · Qtc 0.74, Fc 45 Hz, F3 42.7 Hz
The box lifts resonance from 26.7–28.0 Hz free-air to 45–47 Hz and half power lands at 40.6–42.7 Hz, anechoic, before any cabin gain.

03The watts that reach Xmax (in this enclosure)

Travel scales with the square root of power, so there is one wattage that puts the cone exactly on 13.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 254–275 W unfiltered  →  319–334 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 16 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 13.0 mm 254 W reaches Xmax here
-2 · 275 W, no filter-4 · 254 W, no filter-2 · 319 W with subsonic at 25 Hz, 24 dB/oct-4 · 334 W with subsonic at 25 Hz, 24 dB/octXmax 13.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 13.0 mm. Unfiltered that is 254 W, reached first at 20 Hz. It sits under the 500 W the driver can take thermally, so the enclosure sets the ceiling, not the voice coil. The dashed traces are the same driver behind a subsonic filter at 25 Hz, 24 dB/oct: stopping the cone wasting travel below the passband lets it take 319 W before hitting the same 13.0 mm. That is 26 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs27.97 / 26.72Hzfree-air resonance
Qts0.500 / 0.444-2 / -4
Vas79.47 / 80.54Lequivalent compliance
Sd520.0cm²effective piston area
Xmax13mmone-way linear travel
Pe500Wcontinuous RMS
SPL87.0dB1 W / 1 m, derived from T/S

Driver parameters as published by jlaudio.com. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Same 12W3v3-4 as the standard 30 by 15 box, laid out 41 by 14. One inch shallower, 11 inches longer, and 8.1875 inches tall against 8.3125. Measure all three dimensions before choosing between them.

Height here is set by the 6.65 inch motor, not the airspace: 0.75 inch above the motor is the floor, and at 41 by 14 that already buys 1.573 cubic feet net against the 1.23 the standard box was built to. That is a clearance fact, not a tuning target. More air lowers Qtc, which is the safe direction.

Alignment is Qtc 0.744 with F3 at 42.7 Hz on the 12W3v3-4. The 12W3v3-2 has its own parameters and lands at Qtc 0.834 with F3 at 40.6 Hz.

This is the driver that gains most from the wide box. 80.54 liters of Vas wants air, and the extra volume pulls Qtc down toward 0.707. 87.15 dB sensitivity, single 4 ohm coil, no wiring decision.

Before you order

Questions

Why is this cabinet 41 inches wide instead of 30?

Because it trades length for depth and height. The standard single Down Fire platform is 30 wide by 15 deep; this one is 14 deep, 1 inch shallower, and runs 41 inches long to put the airspace along the length instead.

That lets it stand 8.1875 inches tall against 8.3125 for the standard box. A 12 inch frame needs about 13 inches of baffle, so 14 is as shallow as a 12 can go. If you have 41 inches of run and height or depth is your limit, this is the shape that works.

How does this compare to the standard 30 x 15 12W3v3-4 enclosure?

The standard box is 30 by 15 by 8.3125 inches and holds 1.23 cubic feet net. This one is 41 by 14 by 8.1875 inches and holds 1.573 cubic feet net.

Here the wide box holds more air because its height is set by motor clearance, not by an airspace target. More air lowers Qtc, the safe direction. Choose the standard box when length is limited, this one when depth is the limit and you have 41 inches of run.

What alignment does this enclosure produce?

At 1.573 cubic feet net the 12W3v3-4 gives Qtc 0.744, Fc 44.8 Hz and F3 42.7 Hz, and the 12W3v3-2 gives Qtc 0.834, Fc 46.7 Hz and F3 40.6 Hz, each calculated from that coil's own published Thiele-Small parameters.

That is a little above the 0.707 maximally flat reference, so there is a mild lift near the corner. The figures are anechoic; in a car, cabin gain adds real output below 50 Hz, so in-vehicle response runs deeper.

How much power should I run, and how do I wire it?

JL Audio rates the 12W3v3-4 at 500 watts RMS continuous and recommends 150 to 500 watts of amplifier power. At 87.15 dB sensitivity this driver produces solid output even in the middle of that range. It is a single voice coil at 4 ohms nominal, so there is no series or parallel decision to make: one side mounted cup, and the amplifier sees 4 ohms.

How tall is this once the standoffs are on?

The cabinet is 8.1875 inches tall measured in the down fire position, excluding standoffs. The standoffs hold 1.75 inches under the baffle, so plan your space around 9.9375 inches installed.

The standoffs ship uninstalled, so you can place them to suit your floor, or leave them off and run the cabinet front firing or up firing.

Where is the terminal cup located on a down fire enclosure?

Side mounted. Every Proline X Performance Optimized enclosure uses a side mounted terminal cup regardless of alignment, whether standard, wedge, or down fire. On this cabinet that keeps the connection accessible with the enclosure installed, since the baffle faces the floor. The cup is our Proline X ABS and carbon fiber composite unit with stainless hardware, copper ring terminals, and pre-wired 12 gauge OFC.

How is this enclosure built?

V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF, with square corners as the Down Fire standard. Every panel joint is a machined interlocking groove that locks before adhesive is applied, which keeps the cabinet airtight under sustained pressure cycling.

The 1.5 inch double baffle has its outer layer machined as a flush recess so the driver bolts to the inner layer, and a windowed U-brace stiffens the long panels. Polyfill is installed as a light wall lining; do not add more, since packing a sealed box makes it act larger and moves the alignment. Assembled and inspected in Tullahoma, Tennessee.

Is the JL Audio 12W3v3-4 included with this enclosure?

No. This listing is for the enclosure only. Bring your own JL Audio 12W3v3-4. The cutout and cabinet height are cut direct fit for this driver.

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