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Proline X PO 10-S DFW PS sealed down-fire wide enclosure for the Morel Ultimo PowerSlim PS104D, 41 inches wide by 4.625 inches tall, feet add 1.75 inches of height.
Proline X PO 10-S DFW PS sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 4.625 inches tall by 12 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 10" Enclosure Morel Ultimo PowerSlim PS104D · Single 10" Sealed enclosure

Net volume
0.500 cu ft after displacement
Max mounting depth
3.1 in / 79.6mm, Morel spec
External dimensions
41 in W × 4.625 in in the down fire position H × 12 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 PowerSlim PS104DBuy at Audio Intensity
  • Alignment: 0.500 cu ft net. Qtc 1.164, Fc 48.4 Hz, F3 35.9 Hz
  • Down Fire Wide: 41"W x 12"D x 4.625"H in down fire position, 3" shallower and 11" longer than the standard 30 x 15, for under rear seats and narrow cargo floors
  • Driver: Morel Ultimo PowerSlim PS104D, DVC 4 ohm, 700W RMS / 1800W max, 11mm Xmax each way, 3.1" mounting depth
  • Build: Windowed U-brace, 1.5" double baffle, one side-mounted terminal cup, 12g OFC
  • Feet: 1.75", ship uninstalled. Installed height 6.375"

Spec of record

Technical specifications

SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverMorel Ultimo PowerSlim PS104D (DVC 4 ohm). Direct fit
Enclosure TypeSealed, single driver, down fire, floor coupled
Intended FitmentUnder the rear seat of trucks and SUVs and narrow cargo floors, where depth is the limiting dimension
Firing DirectionDown firing, driver fires toward the floor. Feet ship uninstalled, so front or up firing is also possible
Chamber ConfigurationSingle sealed chamber, windowed U-brace, one side-mounted terminal cup
External Width41 in
External Depth12 in
External Height4.625 in in the down fire position, excludes feet
Installed Height6.375 in with the 1.75 in feet
Standard 30 x 15 Equivalent30 x 15 x 4.9375 in, 0.50 cu ft net. Same driver, deeper and shorter footprint
Internal Volume, Gross0.556 cu ft
Net Volume0.500 cu ft after displacement
Height Set ByAirspace; motor clearance allows a lower cabinet
Clearance Above Motor0.78 in
AlignmentQtc 1.164, Fc 48.4 Hz, F3 35.9 Hz anechoic
Woofer Opening9.1 in / 231.5mm, Morel spec
Mounting Depth Required3.1 in / 79.6mm, Morel spec
Driver Overall Diameter10.35 in / 263mm, Morel spec
Driver Fs29.1 Hz
Driver Qts0.7; Qtc cannot fall below this in any sealed box
Driver Qes / Qms0.9 / 3.6
Driver Vas25 L
Driver Mms / BL203 g / 8.1
Driver Sd346.4 cm2
Driver Xmax11mm each way
Driver Sensitivity82 dB (2.83V/1m)
Driver Voice Coil129.5mm / 5.1 in, four layers carbon, aluminium former
Driver MotorDouble magnet EVC
Driver ConeFlat honeycomb Hexatech aluminium
Morel Sealed Recommendation12.7 liters per driver
Driver Power Handling700 W RMS / 1800 W max transient
Recommended Power350 to 700 W RMS, Morel rated range
Voice Coil ConfigurationDual 4 ohm: 2 ohm parallel or 8 ohm series at the driver
Driver Displacement0.05 cu ft, estimated; Morel publishes none
MaterialLangboard Elite MDF
ConstructionCNC cut on ShopSabre routers, 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, stainless machine screws included
Terminal CupOne Proline X ABS and carbon fiber composite, side mounted
Internal Wiring12 gauge OFC
FeetIncluded, 1.75 in, shipped uninstalled
DampingPolyfill pre-installed as a light wall lining
CarpetPlush Black
Bundle OptionsEnclosure only, bring your own Morel PS104D
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.500
cu ft per chamber
System Qtc
1.16
sealed
Half power
35.9
Hz · F3
Xmax at
314
W RMS · no filter
With 25 Hz subsonic
323
W RMS · +3%
Amplifier
700
W RMS recommended
This enclosure holds 0.500 cu ft net per chamber. In it the Morel Ultimo PowerSlim PS104D runs a system Qtc of 1.16 with half power at 35.9 Hz, and the cone reaches its 11.0 mm travel limit at 314 W, below the driver’s 700 W thermal rating, so travel is what stops you here, not heat. A 25 Hz subsonic filter adds little here: 323 W against 314 W, 3 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 = 32.3
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 D4 32.3
D4 · EBP 32.3
EBP under 50 means a motor that wants a sealed load. The Ultimo PowerSlim PS104D sits at 32.3, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

0.500 cu ft against a 25.0 L Vas.

α = Vas ÷ Vb = 1.77  ·  Fc = Fs√(α+1) = 48 Hz  ·  Qtc = 1.16
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
D4 · Qtc 1.16, Fc 48 Hz, F3 35.9 Hz
The box lifts resonance from 29.1 Hz free-air to 48 Hz and half power lands at 35.9 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 11.0 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 314 W unfiltered  →  323 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 11.0 mm 314 W reaches Xmax here
D4 · 314 W, no filterD4 · 323 W with subsonic at 25 Hz, 24 dB/octXmax 11.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 11.0 mm. Unfiltered that is 314 W, reached first at 38 Hz. It sits under the 700 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: 323 W against 314 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
Fs29.10Hzfree-air resonance
Qts0.700D4
Vas25.00Lequivalent compliance
Sd346.4cm²effective piston area
Xmax11mmone-way linear travel
Pe700Wcontinuous RMS
SPL80.2dB1 W / 1 m, derived from T/S

Driver parameters as published by Morel Ultimo PowerSlim owner's manual, rev 24-12-23. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

700 watts RMS in a driver that mounts in 3.1 inches, now in a cabinet 4.625 inches tall and 12 inches deep. That is about as low and as shallow as a sealed 10 gets.

The reason is the voice coil. Morel uses a 129.5mm coil, 5.1 inches, where most shallow 10s run 2 to 2.5 inches. Four layers of carbon on an aluminium former, which is why it takes 700 watts continuously with 1800 of transient headroom.

Height was solved to Morel's 12.7 liter recommendation, 0.500 cubic feet net, and the motor clears the top panel with just over the 0.75 inch minimum. Qtc lands at 1.164 with F3 at 35.9 Hz. Qts is 0.7, so a flat alignment is not available in any sealed box; the lift near the corner is intended. Morel publishes no displacement, so the 0.05 cubic feet we subtract is our estimate.

Dual 4 ohm coils: 2 ohms parallel or 8 ohms series. Target 350 to 700 watts RMS.

Before you order

Questions

Why is this cabinet 41 inches wide instead of 30?

Because it is only 12 inches deep. The standard Performance Optimized Down Fire platform is 30 wide by 15 deep, and under a rear seat or on a narrow cargo floor there is often not 15 inches to give.

The airspace lost from the depth is recovered from the length, so the cabinet runs 41 inches instead of 30 and stands 4.625 inches tall, with the same driver specific chamber. If you do have 15 inches of depth, the standard 30 by 15 cabinet is the better pick.

How does this compare to the standard 30 x 15 PowerSlim PS104D enclosure?

The standard cabinet is 30 by 15 by 4.9375 inches and gives the driver 0.50 cubic feet net. This one is 41 by 12 by 4.625 inches and gives the driver 0.500 cubic feet net. The height was solved to hold the same airspace as the standard box, so the alignment carries over.

The choice is about shape: the standard box if you have 15 inches of depth, this one when depth is the limit and you have 41 inches of run.

Why is the Qtc above 1.0?

Because the PS104D has a free-air Qts of 0.7, so system Qtc cannot fall below 0.7 in any sealed box, and in Morel's recommended 12.7 liters it lands higher. At 0.500 cubic feet net this cabinet runs Qtc 1.164 with Fc at 48.4 Hz and a predicted F3 of 35.9 Hz.

That is a lift near the corner frequency, more weight and impact rather than a flat anechoic curve. It is the driver's intended voicing, not a compromise.

How do I wire this enclosure and set my impedance?

The PS104D has dual 4 ohm coils, so you set the load at the driver: 2 ohms with the coils in parallel or 8 ohms in series. The one side mounted terminal cup carries that load to the amplifier. Target 350 to 700 watts RMS, Morel's rated range, and confirm your amplifier is stable at the load you choose.

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, and on a down fire cabinet that keeps the connection accessible with the enclosure in its installed position, since the baffle faces 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.

How is this enclosure built?

V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF, so every panel joint locks mechanically before adhesive is applied. The front baffle is a 1.5 inch double layer with the outer layer machined as a flush recess, and the driver lands on 8/32 threaded inserts with stainless machine screws. A windowed U-brace ties the long 41 inch panels together. Corners are square, the Down Fire series standard, which keeps the most internal volume for the footprint. Assembled and inspected in Tullahoma, Tennessee.

Do I need to add polyfill or damping?

No. Polyfill is already installed as a light wall lining, and the quantity is chosen so it does not change the acoustic volume. Do not add more: packing a sealed box makes it behave as though it were larger, which walks the alignment away from the 0.500 cubic feet this cabinet was built to.

Is the Morel PS104D subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own Morel Ultimo PowerSlim PS104D; the driver is purchased separately. The cutout and mounting depth are direct fit, and the 1.75 inch feet ship uninstalled for an installed height of 6.375 inches.

Same series, same size

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