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Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 12" Shallow Sub Enclosure Arc Audio SW12 · Single 12" Sealed enclosure

Net volume
0.752 cu ft after displacement and the brace
Max mounting depth
2.4 in
External dimensions
41 in W × 5.125 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
  • Alignment: 0.752 cu ft net. Coils in series: Qtc 1.001, Fc 53.1 Hz, F3 41.7 Hz; Coils in parallel: Qtc 0.990, Fc 53.1 Hz, F3 41.9 Hz
  • Down Fire Wide: 41"W x 14"D x 5.125"H in down fire position, excludes the 1.75" standoffs (installed height 6.875"). Stands lower than the standard 30 x 15 at 6"
  • Height set by: airspace; 1.98" of clearance above the motor
  • Driver: Arc Audio SW12 (DVC 2 ohm or 4 ohm), 400W RMS / 800W peak, 2.4" mounting depth or 2.23" front loaded, 11" cutout
  • 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 DriverArc Audio SW12 (dual 2 ohm or dual 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 Height5.125 in in the down fire position, excludes standoffs
Installed Height6.875 in including the 1.75 in standoffs
Dimension ReferenceAll external dimensions measured in down fire position
Standard 30 x 15 Version6 in tall, 0.74 cu ft net
Internal Volume, Gross0.801 cu ft
Internal Volume, Net0.752 cu ft after displacement and the brace
Height Set ByAirspace; 1.98 in clearance above the motor
Alignment, Coils in seriesQtc 1.001, Fc 53.1 Hz, F3 41.7 Hz anechoic
Alignment, Coils in parallelQtc 0.990, Fc 53.1 Hz, F3 41.9 Hz anechoic
Woofer Opening11 in
Mounting Depth Required2.4 in
Frame Outer Diameter12.5 in
Driver Displacement0.042 cu ft (Estimated; Arc Publishes None)
Arc Published Sealed Range0.65 Min / 0.8 Optimum / 1.0 Max (All Gross)
Driver Fs33.1 Hz Series / 33.0 Hz Parallel
Driver Qts0.624 Series / 0.616 Parallel
Driver Qes / Qms0.729 / 4.319 Series | 0.719 / 4.289 Parallel
Driver Vas33.44 Liters Series / 33.73 Liters Parallel
Driver Bl23.955 Tm Series / 12.024 Tm Parallel
Driver Mms278.61 g Series / 277.40 g Parallel
Driver Re7.23 Ohms Series / 1.81 Ohms Parallel
Driver Sd532.97 cm²
Driver Sensitivity85.22 dB (1W/1m)
Driver Power Handling400 Watts RMS / 800 Watts Peak
Driver Mounting8/32 Threaded Inserts | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual Voice Coil, Final Impedance Set At The Driver
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 Arc Audio SW12)
Warranty1 year limited (enclosure)
Built InTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
0.752
cu ft per chamber
System Qtc
0.99–1.00
sealed
Half power
41.7–41.9
Hz · F3
Xmax at
1093
W RMS · no filter
With 25 Hz subsonic
1127
W RMS · +3%
Amplifier
400
W RMS recommended
This enclosure holds 0.752 cu ft net per chamber. In it the Arc Audio SW12D4 runs a system Qtc of 0.99–1.00 with half power at 41.7–41.9 Hz, and the cone reaches its 15.5 mm travel limit at 1093 W, above the driver’s 400 W thermal rating, so heat stops you before travel does. A 25 Hz subsonic filter adds little here: 1127 W against 1093 W, 3 percent. The box already resonates at 53 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 = 45.4–45.9
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 series 45.4 parallel 45.9
series · EBP 45.4parallel · EBP 45.9
EBP under 50 means a motor that wants a sealed load. The SW12D4 sits at 45.4–45.9, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

0.752 cu ft against a 33.4 L Vas.

α = Vas ÷ Vb = 1.57  ·  Fc = Fs√(α+1) = 53 Hz  ·  Qtc = 0.99–1.00
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
series · Qtc 1.00, Fc 53 Hz, F3 41.7 Hzparallel · Qtc 0.99, Fc 53 Hz, F3 41.9 Hz
The box lifts resonance from 33.0–33.1 Hz free-air to 53 Hz and half power lands at 41.7–41.9 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 15.5 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 1093–1095 W unfiltered  →  1127–1128 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 15.5 mm 1093 W reaches Xmax here
series · 1095 W, no filterparallel · 1093 W, no filterseries · 1127 W with subsonic at 25 Hz, 24 dB/octparallel · 1128 W with subsonic at 25 Hz, 24 dB/octXmax 15.5 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 15.5 mm. Unfiltered that is 1093 W, reached first at 37 Hz. It sits above the 400 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: 1127 W against 1093 W. At 53 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
Fs33.10 / 33.00Hzfree-air resonance
Qts0.624 / 0.616series / parallel
Vas33.44 / 33.73Lequivalent compliance
Sd533.0cm²effective piston area
Xmax15.5mmone-way linear travel
Pe400Wcontinuous RMS
SPL84.1dB1 W / 1 m, derived from T/S

Driver parameters as published by arcaudio.com SW12 published specification. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

A 12 inch subwoofer that mounts in 2.4 inches, 2.23 front loaded. On 41 by 14 that puts a full 12 in a box 5.125 inches tall.

Height was solved to the airspace: 5.125 tall holds 0.752 net, against 0.74 in the standard box, and the motor clears the lid with 1.98 inches to spare. Same air, lower box.

Series lands at Qtc 1.001 with F3 41.7 Hz, parallel at Qtc 0.990 with F3 41.9 Hz. Pick your wiring on amplifier impedance, not sound.

Arc states sealed volume as gross; this box is 0.801 gross against their 0.8 optimum. 400 watts RMS, 800 peak, 532.97 square centimeters of cone.

Measure installed height, not cabinet height: 5.125 on its own, 6.875 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 5.125 inches tall instead of 6.

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 SW12 enclosure?

Same driver, different shape. The standard cabinet is 30 by 15 by 6 inches and holds 0.74 cubic feet net. This cabinet is 41 by 14 by 5.125 inches and holds 0.752 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.

Does it matter whether I wire the voice coils in series or parallel?

Not for the enclosure alignment. In series the SW12 lands at Qtc 1.001, Fc 53.1 Hz and F3 41.7 Hz; in parallel at Qtc 0.990, Fc 53.1 Hz and F3 41.9 Hz.

Arc's two parameter sets are effectively identical, so choose your wiring based purely on the impedance your amplifier is stable and efficient into.

Why does Arc list gross volume when other brands list net?

Arc Audio publishes its sealed recommendations as gross volume, total internal volume before the driver's displacement, where most manufacturers state net. This cabinet is 0.801 cubic feet gross, on Arc's 0.8 optimum, and 0.752 cubic feet net.

Both figures appear in the specifications so you can compare against either convention.

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 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 0.752 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.

Is the Arc Audio SW12 subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own Arc Audio SW12 in either dual 2 ohm or dual 4 ohm. The cutout and mounting depth are direct fit for either version.

Same series, same size

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