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Performance Optimized · Datasheet

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

Net volume
0.502 cu ft after displacement
Max mounting depth
3.1 in / 79.6mm, Morel spec
External dimensions
41 in W × 7.0625 in in the down fire position H × 12 in D
Front baffle
1.5 in double baffle at both positions, outer layer machined as a flush recess
Buy at Audio IntensityFactory-direct, ships from Tullahoma
Morel Ultimo PowerSlim PS104DBuy at Audio Intensity
  • Alignment: 0.502 cu ft net per chamber, 1.004 total. Qtc 1.163, Fc 48.3 Hz, F3 35.9 Hz per driver
  • Down Fire Wide: 41"W x 12"D x 7.0625"H in down fire position, 3" shallower and 11" longer than the standard 30 x 15, for under rear seats and narrow cargo floors
  • Drivers: Pair of Morel PS104D (DVC 4 ohm), 700W RMS each / 1400W combined, 11mm Xmax each way, 3.1" mounting depth
  • Chambers: Two fully separate sealed chambers, 3/4" MDF full divider, one shared side-mounted terminal cup
  • Feet: 1.75", ship uninstalled. Installed height 8.8125"

Spec of record

Technical specifications

SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverMorel Ultimo PowerSlim PS104D (DVC 4 ohm), pair required. Direct fit
Enclosure TypeSealed, dual 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, both drivers fire toward the floor. Feet ship uninstalled, so front or up firing is also possible
Chamber ConfigurationTwo fully separate chambers, full divider, single shared side-mounted terminal cup
External Width41 in
External Depth12 in
External Height7.0625 in in the down fire position, excludes feet
Installed Height8.8125 in with the 1.75 in feet
Standard 30 x 15 Equivalent30 x 15 x 7.6875 in, 0.50 cu ft net per chamber. Same driver, deeper and shorter footprint
Internal Volume, Gross1.126 cu ft total
Net Volume Per Chamber0.502 cu ft after displacement
Total Net Volume1.004 cu ft
Height Set ByAirspace; motor clearance allows a lower cabinet
Clearance Above Motor3.21 in
Alignment Per ChamberQtc 1.163, Fc 48.3 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
Power Handling700 W RMS / 1800 W max transient each, 1400 W RMS combined
Recommended Power Per Driver350 to 700 W RMS, Morel rated range
Voice Coil ConfigurationDual 4 ohm per driver, final impedance set at the drivers
Driver Displacement0.05 cu ft each, 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 at both positions, outer layer machined as a flush recess
Internal BracingFull-height 3/4 in bonded divider
Corner ProfileSquare, Down Fire series standard
Driver Mounting8/32 threaded inserts, stainless machine screws included, 2 sets
Terminal CupOne Proline X ABS and carbon fiber composite, side mounted
Internal Wiring12 gauge OFC to both driver positions in parallel
FeetIncluded, 1.75 in, shipped uninstalled
DampingPolyfill pre-installed as a light wall lining per chamber
CarpetPlush Black
Bundle OptionsEnclosure only, bring your own pair of Morel PS104D
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.502
cu ft per chamber
System Qtc
1.16
sealed
Half power
35.9
Hz · F3
Xmax at
313
W RMS · no filter
With 25 Hz subsonic
322
W RMS · +3%
Amplifier
700
W RMS recommended
This enclosure holds 0.502 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 313 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: 322 W against 313 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

0.502 cu ft against a 25.0 L Vas.

α = Vas ÷ Vb = 1.76  ·  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 = 313 W unfiltered  →  322 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 313 W reaches Xmax here
D4 · 313 W, no filterD4 · 322 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 313 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: 322 W against 313 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

1400 watts RMS combined in a cabinet 12 inches deep and 7.0625 inches tall. It comes from a pair of drivers that each mount in 3.1 inches.

Each PS104D runs a 5.1 inch voice coil wound in four layers of carbon. Most shallow 10s use a 2 to 2.5 inch coil. That surface area is why these take 700 watts apiece continuously.

Each chamber holds 0.502 cubic feet net, which is Morel's 12.7 liter recommendation. Qtc lands at 1.163 with F3 at 35.9 Hz. That is above unity and it is meant to be: Qts is 0.7, so a flat alignment is not on the table in any sealed box. Morel publishes no displacement for this driver, so the 0.05 cubic feet we subtract is our estimate.

Separate chambers, full-height bonded divider, one shared side-mounted cup. Dual 4 ohm coils on each driver, so set impedance at the drivers and wire both the same.

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 7.0625 inches tall, with each driver in its own separate 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 dual PowerSlim PS104D enclosure?

The standard cabinet is 30 by 15 by 7.6875 inches and gives each driver 0.50 cubic feet net. This one is 41 by 12 by 7.0625 inches and gives each driver 0.502 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 own recommended volume it lands higher. At 0.502 cubic feet net per chamber each driver runs Qtc 1.163 with Fc at 48.3 Hz and a predicted F3 of 35.9 Hz.

That means a lift near the corner frequency, more weight and impact, less of a flat anechoic curve. It is the driver's intended voicing, not a consequence of the wide footprint.

How is this enclosure wired, and how do I set my final impedance?

One side-mounted Proline X terminal cup with a single pair of posts is pre-wired in 12 gauge OFC to both driver positions in parallel. Each PS104D has dual 4 ohm coils, so the way you wire the coils on each driver sets the load the amplifier sees. Wire both drivers identically and confirm the resulting load against your amplifier's minimum stable impedance. Target 350 to 700 watts RMS per driver.

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

Side mounted, and there is one cup serving both chambers. 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 both baffles face 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 to both driver positions in parallel.

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 each driver lands on 8/32 threaded inserts with stainless machine screws. A full-height bonded 3/4 inch divider separates the two chambers and ties the walls together across the 41 inch span. 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 in each chamber, 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 0.502 cubic feet per chamber this cabinet was built to.

Are the Morel PS104D subwoofers included with this enclosure?

No. This listing is for the enclosure only. Bring your own pair of Morel Ultimo PowerSlim PS104D; the drivers are purchased separately. The cutout and mounting depth are direct fit at both positions, and the 1.75 inch feet ship uninstalled for an installed height of 8.8125 inches.

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