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Proline X PO 12-S DFW RSW sealed down-fire wide enclosure for the Alpine RSW12, 41 inches wide by 5 inches tall, feet add 1.75 inches of height.
Proline X PO 12-S DFW RSW sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 5 inches tall by 14 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 12" Shallow Sub Enclosure Alpine RSW12 · Single 12" Sealed enclosure

Net volume
0.709 cu ft after displacement and the brace
Max mounting depth
3.25 in
External dimensions
41 in W × 5 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
Alpine RSW12Buy at Audio Intensity
  • Alignment: 0.709 cu ft net. RS-W12D2, dual 2 ohm: Qtc 1.724, Fc 49.2 Hz, F3 33.7 Hz; RS-W12D4, dual 4 ohm: Qtc 1.790, Fc 51.7 Hz, F3 35.3 Hz
  • Down Fire Wide: 41"W x 14"D x 5"H in down fire position, excludes the 1.75" standoffs (installed height 6.75"). Stands lower than the standard 30 x 15 at 5.75"
  • Height set by: airspace; 1.00" of clearance above the motor
  • Driver: Alpine RS-W12D2 (DVC 2 ohm) or RS-W12D4 (DVC 4 ohm), 600W RMS / 1800W peak, 20mm Xmax, 572 cm2 Sd, neodymium motor
  • Build: Langboard Elite MDF, V-groove and dado, 1.5" double baffle with flush outer recess, windowed U-brace, 12g OFC side-mounted terminal cup

Spec of record

Technical specifications

SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverAlpine RS-W12D2 (DVC 2 ohm) or RS-W12D4 (DVC 4 ohm), quantity 1. Direct fit
Enclosure TypeSealed, down fire, floor coupled
Intended FitmentLong, low spaces where height or depth is the limit and 41 in of run is available
Firing DirectionDown firing. Feet ship uninstalled, so front or up firing is also possible
Chamber ConfigurationSingle chamber, windowed U-brace, one side-mounted terminal cup
External Width41 in
External Depth14 in
External Height5 in in the down fire position, excludes standoffs
Installed Height6.75 in including the 1.75 in standoffs
Dimension ReferenceAll external dimensions measured in down fire position
Standard 30 x 15 Version5.75 in tall, 0.70 cu ft net
Internal Volume, Gross0.766 cu ft
Internal Volume, Net0.709 cu ft after displacement and the brace
Height Set ByAirspace; 1.00 in clearance above the motor
Alignment, RS-W12D2, dual 2 ohmQtc 1.724, Fc 49.2 Hz, F3 33.7 Hz anechoic
Alignment, RS-W12D4, dual 4 ohmQtc 1.790, Fc 51.7 Hz, F3 35.3 Hz anechoic
Woofer Opening11.625 in
Mounting Depth Required3.25 in
Frame Outer Diameter12.82 in
Driver Displacement0.05 cu ft
Driver Fs28.00 Hz (Free-Air Resonance)
Driver Qts0.980 (D2) | 1.003 (D4, derived from Alpine's Qes and Qms)
Driver Vas42.04 L (D2) | 43.84 L (D4)
Driver Cone Area (Sd)572 cm², Largest In The Down Fire Series
Driver Xmax (One-Way)20mm
Driver Xmech (Peak-to-Peak)54mm
Driver Power Handling600 Watts RMS / 1800 Watts Peak
Driver Voice Coil4 Inch, High-Temp USA Wire
Driver MotorHigh-Grade Neodymium, DD Linear Dual Magnetic Gap
Driver Mounting8/32 Threaded Inserts | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual Voice Coil, Final Impedance Set At The Driver
Recommended Power500-600 Watts RMS (Alpine Rated: 600W RMS)
MaterialLangboard Elite 3/4 in MDF
JoineryV-groove and dado, CNC cut on ShopSabre routers
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)
Terminal CupOne Proline X ABS and carbon fiber composite, side mounted, pre-wired 12 gauge OFC
Standoffs1.75 in, included, shipped uninstalled
DampingPolyfill installed as a light wall lining
CarpetPlush black
Bundle OptionsEnclosure only (bring your own RS-W12D2 or RS-W12D4)
Warranty1 year limited (enclosure)
Built InTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
0.709
cu ft per chamber
System Qtc
1.72–1.79
sealed
Half power
33.7–35.3
Hz · F3
Xmax at
1327
W RMS · no filter
With 25 Hz subsonic
1335
W RMS · +1%
Amplifier
500–600
W RMS recommended
This enclosure holds 0.709 cu ft net per chamber. In it the Alpine RS-W12D2 runs a system Qtc of 1.72–1.79 with half power at 33.7–35.3 Hz, and the cone reaches its 20.0 mm travel limit at 1327 W, above the driver’s 600 W thermal rating, so heat stops you before travel does. A 25 Hz subsonic filter adds little here: 1335 W against 1327 W, 1 percent. The box already resonates at 49–52 Hz, so its own rolloff has removed most of what the filter would have stopped.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 24.3–24.8
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 D2 24.3 D4 24.8
D2 · EBP 24.3D4 · EBP 24.8
EBP under 50 means a motor that wants a sealed load. The RS-W12D2 sits at 24.3–24.8, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

0.709 cu ft against a 42.0 L Vas.

α = Vas ÷ Vb = 2.09  ·  Fc = Fs√(α+1) = 49–52 Hz  ·  Qtc = 1.72–1.79
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
D2 · Qtc 1.72, Fc 49 Hz, F3 33.7 HzD4 · Qtc 1.79, Fc 52 Hz, F3 35.3 Hz
The box lifts resonance from 28.0–29.0 Hz free-air to 49–52 Hz and half power lands at 33.7–35.3 Hz, anechoic, before any cabin gain. This enclosure ships without a driver, so both coil variants the maker offers are plotted. They do not load the same box the same way.

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 20.0 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 1327–1328 W unfiltered  →  1335–1340 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 20.0 mm 1327 W reaches Xmax here
D2 · 1328 W, no filterD4 · 1327 W, no filterD2 · 1340 W with subsonic at 25 Hz, 24 dB/octD4 · 1335 W with subsonic at 25 Hz, 24 dB/octXmax 20.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 20.0 mm. Unfiltered that is 1327 W, reached first at 47 Hz. It sits above the 600 W the driver can take thermally, so the voice coil gives up before the suspension does. The dashed traces are the same driver behind a subsonic filter at 25 Hz, 24 dB/oct, and they sit almost on top of the solid ones: 1335 W against 1327 W. At 49–52 Hz the filter sits well below resonance, where the sealed alignment has already rolled the cone off at 12 dB/oct, so there is little wasted travel left for it to recover. Set it anyway to keep road rumble out of the cone, but do not size the amplifier around it.
ParamValueUnitNote
Fs28.00 / 29.00Hzfree-air resonance
Qts0.980 / 1.003D2 / D4
Vas42.04 / 43.84Lequivalent compliance
Sd572.0cm²effective piston area
Xmax20mmone-way linear travel
Pe600Wcontinuous RMS
SPL80.9dB1 W / 1 m, derived from T/S

Driver parameters as published by Alpine R-Series Shallow application guide · Alpine R-Series Shallow application guide (Qts corrected from an impossible printed 1.49). Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

A 12 inch subwoofer in a cabinet 5 inches tall. If you want 12 inch cone area and have almost no vertical clearance but 41 inches of run, nothing else we build gets lower.

Height was solved to the airspace: 5 tall holds 0.709 net, against 0.70 in the standard box, and the motor clears the lid with 1.00 inches to spare. Same air, lower box.

Neodymium again: Alpine publishes 0.05 cubic feet of displacement, so nearly all of the cabinet is usable air. The D2 lands at Qtc 1.724 with F3 33.7 Hz, the D4 at Qtc 1.790 with F3 35.3 Hz. Underdamped, as every sealed box for this driver is.

Dual voice coil in either 2 ohm or 4 ohm. Set your final impedance at the driver. Target 500 to 600 watts RMS.

Measure installed height, not cabinet height: 5 on its own, 6.75 with the 1.75 inch feet on. The standard 30 by 15 is still the pick if you do not have 41 inches of run.

Before you order

Questions

Why is this cabinet 41 inches wide instead of 30?

Because it trades length for depth and height. The standard Performance Optimized Down Fire platform is 30 wide by 15 deep; this one is 14 deep, 1 inch shallower, and 41 long. Spreading the airspace along 11 more inches lets the cabinet stand 5 inches tall instead of 5.75.

Fourteen inches of depth is the practical minimum, since a 12 inch frame needs about 13 inches of baffle. If your space is long and low rather than deep or tall, this is the shape that fits.

How does this compare to the standard 30 x 15 RS-W12 enclosure?

Same driver, different shape. The standard cabinet is 30 by 15 by 5.75 inches and holds 0.70 cubic feet net. This cabinet is 41 by 14 by 5 inches and holds 0.709 cubic feet net.

The airspace is effectively the same, so the driver behaves the same way in either. Choose the standard box when length is limited; choose this one when height or depth is the limit and you have 41 inches of run.

What alignment does this cabinet produce, and why is Qtc so high?

At 0.709 cubic feet net the RS-W12D2 lands at Qtc 1.724, Fc 49.2 Hz and F3 33.7 Hz; the RS-W12D4 at Qtc 1.790, Fc 51.7 Hz and F3 35.3 Hz.

Qts on this driver is close to 1.0 and system Qtc can never fall below Qts, so no sealed box makes it flat. The rise near the corner is the character of the driver, and in a car it lands where cabin gain is already climbing.

Should I choose the RS-W12D2 or the RS-W12D4?

Both fit this cabinet identically and carry the same 600 watt RMS rating, 20mm Xmax and neodymium motor. The RS-W12D2 gives a 1 ohm load in parallel or 4 ohms in series; the RS-W12D4 gives 2 ohms in parallel or 8 ohms in series.

Choose whichever produces a load your amplifier is stable and efficient at. Alpine's application guide ships with the driver and diagrams every option.

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, whether standard, wedge or down fire, which keeps the connection accessible with the baffle facing the floor. The cup is our Proline X ABS and carbon fiber composite unit, recessed, with stainless hardware, copper ring terminals and pre-wired 12 gauge OFC.

Why are the corners square instead of radiused?

Down Fire cabinets are built with square corners as a series standard. The 3 inch top down corner radius used on other Proline X alignments does not apply here. A down fire box is a low, long platform that sits flat against a floor or cargo deck, and square corners maximize usable internal volume for a given footprint while keeping the cabinet stable on its mounting surface.

How is this enclosure built?

V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF. Every panel joint is a machined interlocking groove that locks the panels before adhesive is applied, which keeps the cabinet airtight under sustained pressure cycling. The front baffle is a 1.5 inch double layer, the outer layer machined as a flush recess around the 11.625 inch cutout.

A windowed U-brace stiffens the long panels, and polyfill is installed as a light wall lining. Do not add more fill; packing a sealed box makes it act larger and moves the alignment off the 0.709 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.

Is the Alpine RS-W12 subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own Alpine RS-W12D2 or RS-W12D4. The cutout and mounting depth are direct fit for either version.

Same series, same size

Other Performance Optimized models