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Proline X PO 12-S DFW SCX sealed down-fire wide enclosure for the Morel Ultimo SCX122, 41 inches wide by 7.125 inches tall, feet add 1.75 inches of height.
Proline X PO 12-S DFW SCX sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 7.125 inches tall by 14 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 12" Enclosure Morel Ultimo SCX122 · Single 12" Sealed enclosure

Net volume
1.269 cu ft after displacement and the brace
Max mounting depth
5.571 in
External dimensions
41 in W × 7.125 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
Morel Ultimo SCX122Buy at Audio Intensity
  • Alignment: 1.269 cu ft net. Qtc 1.037, Fc 47.6 Hz, F3 36.8 Hz
  • Down Fire Wide: 41"W x 14"D x 7.125"H in down fire position, excludes the 1.75" standoffs (installed height 8.875"). Stands lower than the standard 30 x 15 at 8.25"
  • Height set by: motor clearance, 0.75" above the 5.571" deep motor; holds more air than the standard box's 1.20
  • Driver: Morel Ultimo SCX122, DVC, 600W RMS / 1500W max transient, 9mm Xmax each way, 32.1 Hz Fs, 5.571" mounting depth
  • 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 DriverMorel Ultimo SCX122 (dual voice coil), 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 Height7.125 in in the down fire position, excludes standoffs
Installed Height8.875 in including the 1.75 in standoffs
Dimension ReferenceAll external dimensions measured in down fire position
Standard 30 x 15 Version8.25 in tall, 1.20 cu ft net
Internal Volume, Gross1.358 cu ft
Internal Volume, Net1.269 cu ft after displacement and the brace
Height Set ByMotor clearance: 0.75 in above the motor, so the box holds more air than the standard version
AlignmentQtc 1.037, Fc 47.6 Hz, F3 36.8 Hz anechoic
Woofer Opening10.4 in
Mounting Depth Required5.571 in
Frame Outer Diameter12.008 in
Driver Displacement0.08 cu ft, estimated; Morel publishes no displacement figure, so the 12 inch rule of thumb is used
Morel Recommended Sealed Volume1.3 net (Morel)
Driver Fs32.1 Hz
Driver Qts0.7, Qtc Cannot Fall Below This In Any Sealed Box
Driver Qes / Qms1.03 / 2.13
Driver Vas43 Liters
Driver Mms149.1 g
Driver BL7.97
Driver Sd430 cm²
Driver Xmax±9mm
Driver DC Resistance2.2 Ohm (Coils In Parallel)
Driver Sensitivity82.9 dB (1W/1m)
Driver Power Handling600 Watts RMS / 1500 Watts Max Transient
Driver Frequency Response10-500 Hz
Driver ConeMulti-Layer Paper and Carbon Fiber
Driver Voice Coil130mm / 5.1" | Hexatech Aluminium Former
Driver MotorDouble Ferrite Vented
Voice Coil ConfigurationDual Voice Coil, Final Impedance Set At The Driver
Mounting Hardware8/32 Threaded Inserts | Stainless Steel Machine Screws Included
Recommended Power300-600 Watts RMS (Morel Rated Range)
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 Morel SCX122)
Warranty1 year limited (enclosure)
Built InTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
1.269
cu ft per chamber
System Qtc
1.04
sealed
Half power
36.8
Hz · F3
Xmax at
178
W RMS · no filter
With 25 Hz subsonic
187
W RMS · +5%
Amplifier
600
W RMS recommended
This enclosure holds 1.269 cu ft net per chamber. In it the Morel Ultimo SCX122 runs a system Qtc of 1.04 with half power at 36.8 Hz, and the cone reaches its 9.0 mm travel limit at 178 W, below the driver’s 600 W thermal rating, so travel is what stops you here, not heat. A 25 Hz subsonic filter adds little here: 187 W against 178 W, 5 percent. The box already resonates at 48 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 = 31.2
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 2 ohm 31.2
2 ohm · EBP 31.2
EBP under 50 means a motor that wants a sealed load. The Ultimo SCX122 sits at 31.2, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

1.269 cu ft against a 43.0 L Vas.

α = Vas ÷ Vb = 1.20  ·  Fc = Fs√(α+1) = 48 Hz  ·  Qtc = 1.04
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
2 ohm · Qtc 1.04, Fc 48 Hz, F3 36.8 Hz
The box lifts resonance from 32.1 Hz free-air to 48 Hz and half power lands at 36.8 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 9.0 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 178 W unfiltered  →  187 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 9.0 mm 178 W reaches Xmax here
2 ohm · 178 W, no filter2 ohm · 187 W with subsonic at 25 Hz, 24 dB/octXmax 9.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 9.0 mm. Unfiltered that is 178 W, reached first at 35 Hz. It sits under the 600 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, and they sit almost on top of the solid ones: 187 W against 178 W. At 48 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
Fs32.10Hzfree-air resonance
Qts0.7002 ohm
Vas43.00Lequivalent compliance
Sd430.0cm²effective piston area
Xmax9mmone-way linear travel
Pe600Wcontinuous RMS
SPL83.3dB1 W / 1 m, derived from T/S

Driver parameters as published by Morel Ultimo SCX subwoofer manual v15. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

The SCX122 is the better of the two SCX drivers acoustically: 32.1 Hz free-air resonance, 43 liters of Vas, and a 130mm voice coil that takes 600 watts RMS with 1500 of transient headroom.

Height on this one is set by the motor, not the air. 5.571 inches of mounting depth plus 0.75 of clearance above the motor puts the cabinet at 7.125 tall, and on 41 by 14 that holds 1.269 net, more than the 1.20 in the standard box. More air, lower Qtc. That is the safe direction.

At 1.269 net it lands at Qtc 1.037 with F3 36.8 Hz. Qts is 0.7, so Qtc cannot go below that in any sealed box; just above unity with a modest lift is what this driver does.

Dual voice coil, final impedance at the driver per Morel's diagrams. Target 300 to 600 watts RMS.

Measure installed height, not cabinet height: 7.125 on its own, 8.875 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 7.125 inches tall instead of 8.25.

Here the height is set by the 5.571 inch mounting depth of the SCX122, which needs 0.75 inch of air above the motor, so the wide box ends up holding 1.269 cubic feet net, more than the standard box. Fourteen inches of depth is the practical minimum, since a 12 inch frame needs about 13 inches of baffle.

How does this compare to the standard 30 x 15 SCX122 enclosure?

Same driver, different shape. The standard cabinet is 30 by 15 by 8.25 inches and holds 1.20 cubic feet net. This cabinet is 41 by 14 by 7.125 inches and holds 1.269 cubic feet net.

The wide box holds more air because its height is set by motor clearance rather than airspace, which lowers Qtc a little. 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.

Why is the Qtc just above 1.0?

The SCX122 has a free-air Qts of 0.7, and system Qtc can never fall below the driver's Qts regardless of enclosure size, so no sealed box reaches a textbook 0.707 alignment with it.

At 1.269 cubic feet net this cabinet sits at Qtc 1.037 with Fc 47.6 Hz and a predicted F3 of 36.8 Hz, computed from Morel's published parameters. The modest lift near the corner is the intended character of the driver.

How do I wire this enclosure and what power should I run?

One side-mounted Proline X terminal cup pre-wired in 12 gauge OFC. The SCX122 is dual voice coil, so set the final impedance at the driver per Morel's wiring diagrams.

Morel rates it at 600 watts RMS and 1500 watts maximum transient. Target 300 to 600 watts RMS and confirm your amplifier is stable at the load you wire.

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 10.4 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 1.269 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.

Is the Morel SCX122 subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own Morel Ultimo SCX122. The cutout and mounting depth are cut specifically for this driver.

Same series, same size

Other Performance Optimized models