Proline X

Performance Optimized Down Fire Sealed 10" Enclosure | Kicker CompRT

SKU: PO 10-S DF CompRT

QUICK SPECS

Alignment: 0.80 cu ft net, Qtc 0.922, Fc 48.2 Hz, F3 40.0 Hz - controlled sealed tune from Klippel-measured T/S
Driver: Kicker 48CWRT104 CompRT 10 (DVC 4Ω), 400W RMS, 13.35mm linear excursion, 3-7/16" top-mount depth
Build: Proline X V-groove and dado joinery, double-layer 1.5" front baffle, perimeter cross-brace, 12g OFC side-mounted terminal cup
Cabinet: 30"W x 15"D x 6.125"H measured in down fire position, square corners

Shipping Included No freight charges at checkout. What you see is what you pay.

Built in Tennessee CNC cut from 3/4" Langboard Elite MDF. V-groove and dado joinery.

Advanced Terminal Cup Built in-house. ABS/Carbon Fiber. Stainless steel hardware. Copper ring terminals.

$ 229.99

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Performance Optimized Down Fire Sealed 10" Enclosure | Kicker CompRT

$ 229.99

Enclosure Type Sealed

External Dimensions 30" W x 15" D x 6.125" H (measured in down fire position)

Net Volume 0.80cu ft

Tuning Frequency N/A (Sealed)

Cutout Diameter Direct Fit

Front Panel Thickness 1.5"

Max Mounting Depth Direct Fit

INSTALLER'S TAKE

The CompRT is the shallow I have recommended most often over the years, and the Klippel data explains why. A 32.3 Hz free-air resonance on a driver with a 3-7/16 inch mounting depth is not normal. Most shallows land in the high 30s or 40s because the shortened motor and stiff suspension push Fs up. Kicker got this one down into territory that lets it actually reach low, which is the whole reason a thin driver can sound like a real subwoofer instead of a midbass with ambition.

Qts of 0.618 is the other number worth noting. That is a well-behaved figure, not the 0.9 to 1.05 you see on shallows built purely for punch. It means this driver has real options in a sealed box rather than being locked into an underdamped alignment no matter what you build.

At 0.80 net it lands at Qtc 0.922 with Fc 48.2 Hz and F3 at 40.0 Hz. Slightly above unity, which gives a modest lift at the corner and the composed, controlled character the CompRT is known for. You could go bigger. At 1.25 net, the top of Kicker's range, it improves to Qtc 0.826 and F3 37.8 Hz. But that costs nearly two inches of cabinet height for 2.2 Hz, and on a down fire box built to vanish under a seat, height is the entire point. 0.80 is the right call for this format.

The double-baffle 1.5 inch front matters on a cabinet only 6.125 inches tall. Short panel spans leave little room for bracing geometry, so the baffle carries more of the structural load than it would in a taller box. Two bonded 3/4 inch layers with a CNC-precision cutout give the driver a mounting platform that will not flex back into the cone.

Dual 4-ohm, so you have two clean options at the driver: coils in parallel for a 2 ohm load, or in series for 8 ohms. Most single-driver builds want the 2 ohm. Target 300 to 400 watts RMS.

Product Details

The Performance Optimized Down Fire Sealed 10" Enclosure for the Kicker CompRT is a low-profile sealed cabinet built around Kicker's shallow-mount CompRT 10" subwoofer. At 6.125 inches tall on a 30 by 15 inch footprint, it fits under seats and behind back benches where a conventional box will not go.

The Kicker 48CWRT104 is a dual 4-ohm subwoofer rated 400 watts RMS with a 3-7/16 inch top-mount depth. Injection-molded polypropylene cone, Santoprene rubber surround with Kicker's signature red double stitching, SoloKon integrated cone-to-backplate design, and Forced-Air Cooling that runs the motor roughly 20 percent cooler. The cone and surround are UV resistant, which is why this driver shows up in UTV and open-cab builds as often as it does in trucks.

The Thiele-Small data behind this enclosure comes from Klippel measurement rather than a datasheet estimate: Fs 32.3 Hz, Qts 0.618, Vas 27.80 liters, Bl 19.158 Tm, Mms 150.85 g, Sd 349.67 cm², and 13.35mm of linear excursion. A 32.3 Hz free-air resonance on a shallow 10 is genuinely low, and it is the single parameter that makes this driver work as well as it does in a thin cabinet.

The 0.80 cubic foot net volume produces Qtc 0.922, Fc 48.2 Hz, and a predicted anechoic F3 of 40.0 Hz. That is a controlled alignment just above unity, giving a modest lift near the corner frequency with the tight, composed character the CompRT is known for. Kicker's published sealed range runs 0.4 to 1.25 cubic feet and 0.80 sits comfortably in the middle of it.

Going larger is possible but not worth it here. At 1.25 net the alignment improves to Qtc 0.826 with F3 at 37.8 Hz, which buys 2.2 Hz of extension in exchange for nearly two additional inches of cabinet height. On a down fire shallow build meant to disappear under a seat, that trade goes the wrong way.

Firing down into the floor, the sealed rolloff meets rising cabin gain below 60 Hz, and in-car response extends well below the anechoic figure.

Construction is the full Proline X Performance Optimized platform: ShopSabre CNC-cut Langboard Elite MDF with V-groove and dado joinery, perimeter cross-bracing, and a double-layer 1.5 inch front baffle (two 3/4 inch sheets bonded) for maximum baffle rigidity and driver isolation. Corners are square on Down Fire cabinets. The driver fires down into the floor with the terminal cup side mounted, keeping the connection accessible with the cabinet in place. Terminal cup is our Proline X ABS/carbon fiber composite pre-wired with 12 gauge OFC.

Bring your own Kicker 48CWRT104. Dual 4-ohm, so you set your final impedance at the driver: 2 ohms with the coils in parallel, 8 ohms in series.

Manufactured in Tullahoma, Tennessee. 1-year enclosure warranty.

Specifications

Enclosure Type	Sealed \| Down Fire Geometry \| Floor-Coupled
Driver-Specific Fitment	Kicker 48CWRT104 CompRT 10 (DVC 4Ω)
Internal Volume (Gross)	0.833 Cubic Feet
Internal Volume (Net)	0.80 Cubic Feet
Target System Qtc	0.922 (Computed from Klippel-Measured T/S)
Predicted Fc	48.2 Hz
Predicted F3 (Anechoic)	40.0 Hz
Driver Fs	32.3 Hz (Klippel)
Driver Qts	0.618 (Klippel)
Driver Qes / Qms	0.6635 / 9.097 (Klippel)
Driver Vas	27.80 Liters / 0.982 Cubic Feet (Klippel)
Driver Bl	19.158 Tm (Klippel)
Driver Mms	150.85 g (Klippel)
Driver Cms	0.161 mm/N (Klippel)
Driver Re	7.945 Ohm (Klippel)
Driver Sd	349.67 cm² (Klippel)
Driver Xmax	13.35mm Linear (Klippel)
Kicker Published Sealed Range	0.4 - 1.25 Cubic Feet
Baffle Configuration	Down Firing - Driver Fires Toward Floor
Material	Langboard Elite 3/4" MDF
Front Baffle Construction	Double-Layer 1.5" MDF (Two 3/4" Sheets Bonded)
Joinery	V-Groove and Dado (CNC-Cut)
Corner Profile	Square (Down Fire Series Standard)
Construction	ShopSabre CNC / Perimeter Cross-Brace
External Width	30 Inches
External Depth	15 Inches
External Height	6.125 Inches
Dimension Reference	All External Dimensions Measured In Down Fire Position
Mounting Hole Diameter	9.125 Inches (Kicker Spec)
Mounting Depth Required	3.4375 Inches Top-Mount (Kicker Spec)
Voice Coil Configuration	Dual 4-Ohm - 2Ω Parallel or 8Ω Series At The Driver
Mounting Hardware	8/32 Threaded Inserts \| Stainless Steel Machine Screws Included
Terminal Cup	Proline X ABS/Carbon Fiber Composite \| Side Mounted \| 12g OFC Pre-Wired
Damping	Polyfill Pre-Installed
Recommended Power	300-400 Watts RMS (Kicker Rated: 400W RMS Continuous)
Carpet Finish	Dark Gray Trunkliner (Standard) or Plush Black (+$10)
Bundle Options	Enclosure Only (Bring Your Own 48CWRT104)
Warranty	1-Year Limited (Enclosure)
Manufactured	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

0.80

cu ft per chamber

System Qtc

0.78–0.92

sealed

Half power

39.4–42.1

Hz · F3

Xmax at

255

W RMS · no filter

With 25 Hz subsonic

316

W RMS · +24%

Amplifier

200–400

W RMS recommended

This enclosure holds 0.80 cu ft net per chamber. In it the Kicker CompRT 10 (48CWRT102) runs a system Qtc of 0.78–0.92 with half power at 39.4–42.1 Hz, and the cone reaches its 13.35 mm travel limit at 255 W, below the driver’s 400 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 316 W — +61 W, or 24 percent more power for the same 13.35 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 48.7–56.8

D2 · EBP 56.8D4 · EBP 48.7

The CompRT 10 (48CWRT102) straddles the boundary at 48.7–56.8 depending on coil — part sealed-band, part transition. Either way it takes a sealed load happily; the coil you run shifts the alignment more than it shifts this verdict.

02What the box does to it

0.80 cu ft against a 35.4 L Vas.

α = Vas ÷ Vb = 1.56 · Fc = Fs√(α+1) = 46–48 Hz · Qtc = 0.78–0.92

D2 · Qtc 0.78, Fc 46 Hz, F3 42.1 HzD4 · Qtc 0.92, Fc 48 Hz, F3 39.4 Hz

The box lifts resonance from 28.7 Hz free-air to 46–48 Hz and half power lands at 39.4–42.1 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 13.35 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 255–311 W unfiltered → 316–336 W with a 25 Hz subsonic

D2 · 255 W, no filterD4 · 311 W, no filterD2 · 316 W with subsonic at 25 Hz, 24 dB/octD4 · 336 W with subsonic at 25 Hz, 24 dB/octXmax 13.35 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 13.35 mm. Unfiltered that is 255 W, reached first at 20 Hz. It sits under the 400 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: stopping the cone wasting travel below the passband lets it take 316 W before hitting the same 13.35 mm. That is 24 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	28.70	Hz	free-air resonance
Qts	0.486 / 0.618		D2 / D4
Vas	35.36 / 27.80	L	equivalent compliance
Sd	349.7	cm²	effective piston area
Xmax	13.35	mm	one-way linear travel
Pe	400	W	continuous RMS
SPL	84.0	dB	1 W / 1 m, derived from T/S

Driver parameters as published by Kicker published Klippel T/S sheet. Curves computed against this enclosure’s actual net airspace.

Materials

Material

Built From a Spec Sheet, Not a Sales Sheet

Every Proline X Performance Series enclosure is CNC-cut from Langboard Elite MDF, 3/4" (18mm) panels produced to published mill specifications. Most enclosure manufacturers source generic MDF without published data. We can tell you the internal bond rating, the modulus of elasticity, the modulus of rupture, and the face and edge screw holding strength for every panel in this enclosure, because we chose the material based on those numbers, not on price or availability.

Langboard Elite is produced in the United States. The specifications below are pulled directly from Langboard's published mill data and are verifiable. This is the same panel stock used in our full Proline X lineup.

Specifications

Langboard Elite MDF: Published Mill Data

Property	Value	Why It Matters
Panel Stock	Langboard Elite MDF	Named, verifiable panel source, not generic "high-density MDF"
Thickness	3/4" (18mm)	Industry standard for subwoofer enclosures; panels below this flex under pressure
Density	48.5 lbs/ft³	Higher density = less porosity, better screw retention, reduced resonance
Internal Bond	200 psi	Measures resistance to delamination under sustained internal pressure. The most enclosure-relevant spec on this sheet
Modulus of Rupture (MOR)	4,200 psi	Bending strength before the panel breaks, relevant for larger unsupported baffle spans
Modulus of Elasticity (MOE)	410,000 psi	Stiffness under load; higher MOE means less panel flex under bass pressure, less resonance
Face Screw Holding	325 lbs	How firmly the panel surface holds a screw; critical for baffle joint integrity over time
Edge Screw Holding	250 lbs	Panel edge retention, relevant for every joint that isn't face-to-face

Internal Bond

200 psi: The Number That Actually Matters for Enclosures

The internal bond rating measures how well the MDF panel resists delamination under sustained pressure applied perpendicular to the face. In a subwoofer enclosure, every bass transient generates a pressure pulse that pushes outward on every panel simultaneously. A panel that begins to delaminate internally loses stiffness gradually. The symptoms are slow: a box that starts to sound softer, less defined, less punchy over months of use. 200 psi internal bond is the spec that determines how long this enclosure holds its acoustic integrity under daily use at real power levels.

Stiffness

410,000 psi MOE: Less Flex, Less Resonance

The modulus of elasticity measures panel stiffness, its resistance to bending under load. A stiffer panel flexes less under the pressure generated by a high-excursion driver at volume. Panel flex is a source of acoustic coloration: the panel itself begins to radiate sound at its own resonant frequency, adding distortion to the output. 410,000 psi stiffness combined with V-groove and dado joinery means the panels stay rigid and the bracing controls resonance at the structure level, not the panel level. The bass you hear comes from the driver, not the box.

Screw Holding

325 lb Face / 250 lb Edge: Joints That Stay Locked

Screw holding strength determines how firmly the panel grips a fastener at the face and at the edge. This matters most at the baffle joint, where the front panel meets the side panels and where the driver is mounted. A panel with low screw holding strength allows fasteners to loosen over time under vibration, leading to air gaps at the joint and loss of acoustic seal. 325 lb face screw holding strength means the baffle hardware stays put. Combined with dado joinery and adhesive, the front panel on a Proline X Performance Series enclosure is not going anywhere.

Sourcing

Named Panel Stock: Not "Premium MDF"

The phrase "premium MDF" or "high-density MDF" appears on marketing copy for enclosures across every price point, from $40 to $400. It is not a specification. It is a description with no defined standard. Langboard Elite is a named, sourced, mill-documented product with published data. We name it in our copy because naming it holds us accountable to the spec. You can look up Langboard Elite independently, verify the numbers on this page, and confirm you are getting what we say you are getting. That is the point.

Why Proline X?

Most enclosures are built to a price point. Proline X is built to a spec. Every box starts with published-data MDF, gets CNC-cut to exact internal volume, and is assembled by hand in our Tennessee facility. The difference shows up in the measurements — and in how the box holds up two years into daily use.

CNC-Cut to Spec

Panels are machine-cut on ShopSabre CNC routers and joined with V-groove and dado joinery. Consistent geometry, no hand-cut variance, no gaps at the joints.