Proline X PO 12-S W SPK12 sealed wedge, front baffle with gloss black insert and pre-wired leads, 21.8 by 15 inches.

Proline X

AudioControl Spike SPK-12 Box: Sealed 12" Wedge Enclosure

Q: Does this fit the AudioControl Spike SPK-12, and will any other 12 inch fit?

The Spike SPK-12, yes, in both coil versions. The baffle is cut to 11.125 in for AudioControl's 12.760 in frame. The 6.14 inch motor clears the cabinet with 0.75 inch to spare.Any other 12, no. The airspace is engineered around the Spike SPK-12's own Qts and Vas, and a different woofer that happened to drop into the hole would not see the alignment printed on this page.

Q: What amplifier power should I run, and how should I wire it?

AudioControl rates the Spike SPK-12 at 500 watts RMS, so target 350 to 500 watts RMS at the final load.AudioControl sells the SPK-12 as SPK-12S2 (single 2 ohm) and SPK-12S4 (single 4 ohm): the SPK-12S2 (single 2 ohm) is a single 2 ohm coil, a 2 ohm load; the SPK-12S4 (single 4 ohm) is a single 4 ohm coil, a 4 ohm load. A parallel load at or under 1 ohm needs an amplifier rated for it. Confirm your amplifier's minimum stable impedance first.

Q: Why the wedge angle, and why rear-firing into the trunk?

The seat-side face carries a 20 degree rake that matches the lean of a factory rear seat back, so the cabinet sits flush against it and the cargo space in front stays usable. The baffle is the vertical trunk-lid-side face, so the driver fires rearward into the trunk cavity.The trunk acts as an acoustic extension for the sealed box, and the cabin adds real output below 50 Hz, so in-vehicle response runs deeper than the anechoic 42.1 Hz on the SPK-12S2 (single 2 ohm) and 44.1 Hz on the SPK-12S4 (single 4 ohm) on this page.

Q: Why is the front baffle double-layered?

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A single 3/4 inch panel flexes under the pressure a 12 inch woofer puts on it at 500 watts, which smears output and works the driver loose over time; the second layer stiffens the face and gives the mounting hardware twice the material to bite.The outer layer is machined as a flush recess to AudioControl's 12.760 inch frame, so the driver bolts to the inner layer and sits flush with the gloss black acrylic insert.

Q: What is the expected low-frequency extension?

Anechoic F3 is 42.1 Hz on the SPK-12S2 (single 2 ohm) and 44.1 Hz on the SPK-12S4 (single 4 ohm). Above Qtc 0.707 F3 sits below fc, so the response carries a small lift near resonance before it rolls off.Those figures exclude cabin gain. In a car the cabin's transfer function adds real output below 50 Hz, so in-vehicle response runs deeper than the numbers above.

Q: Do I need to add polyfill or damping?

No. Polyfill is already installed as a light wall lining to control internal reflections, and the quantity is chosen so it does not change the acoustic volume.Do not add more. Packing a sealed box with fill makes it behave as though it were larger, which walks the alignment away from the 1.00 cubic feet this cabinet was built to.

Q: Is the driver included, and are the threaded inserts installed?

No driver. This is an enclosure only. You receive the cabinet finished in plush black carpet with the gloss black acrylic baffle insert, one side-mounted pre-wired terminal cup, the polyfill lining already in place, and a threaded insert kit with stainless machine screws.The inserts are not pre-installed: AudioControl publishes no bolt circle for the SPK-12, so set the driver in its recess, mark its holes, drill and press the inserts. The AudioControl Spike SPK-12 is purchased separately, and the cabinet is cut direct fit to it, not a general purpose 12 inch box.

SKU: PO 12-S W SPK12 BB

QUICK SPECS

Best For: AudioControl Spike SPK-12 Trunk-Fit Builds
Net Volume: 1.00 cu ft (1.10 cu ft Gross)
Driver Match: AudioControl Spike SPK-12 (SPK-12S2 (single 2 ohm) and SPK-12S4 (single 4 ohm))
Construction: Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Insert Kit

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.

$ 299.99

Acrylic Insert Color

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

AudioControl Spike SPK-12 Box: Sealed 12" Wedge Enclosure

Enclosure Type Sealed

External Dimensions 21.75" W x 15" H x 13.04" D at base tapering to 7.58" D at top

Gross Volume 1.10 cu ft

Net Volume 1.00 cu ft

Shipping Weight 36 lbs

Front Panel Thickness 1.5"

INSTALLER'S TAKE

1.00 cubic feet: Qtc 0.928 on the SPK-12S2 (single 2 ohm) and Qtc 1.024 on the SPK-12S4 (single 4 ohm), F3 42.1 Hz on the SPK-12S2 (single 2 ohm) and 44.1 Hz on the SPK-12S4 (single 4 ohm).

The 6.14 inch motor clears the raked back with 0.75 to spare; the airspace sets the rest of the cabinet.

AudioControl measures the 2 ohm and 4 ohm SPK-12 as separate drivers and they do not match, so every coil is aligned on its own figures. Their numbers hold together on every check I run.

No bolt circle is published, so the insert kit ships in the box: mark, drill and press at install. Sealed, so leave the polyfill as it is and run it at 500 watts or under per driver.

Product Details

Performance Optimized Wedge | AudioControl Spike SPK-12

12" Sealed Wedge Enclosure | Rear-Firing Trunk-Load Design

1.00 ft3 Net1.10 ft3 GrossQtc 0.93 to 1.02Single Chamber Wedge21.75" x 15" x 7.58/13.04"Built in Tennessee

The AudioControl Spike SPK-12 in a Sealed Wedge

The SPK-12 is AudioControl's 12 inch Spike: a mica-coated fiber matrix paper cone, a three-layer high-temperature coil former, a dual damping system and a heavy-duty motor, with a removable grille, rated 500 watts RMS with 14 mm of one-way excursion, 6.14 inches of mounting depth on a 12.76 inch frame. Every Thiele-Small figure comes from AudioControl's own Spike Series user guide, one full parameter block per coil, and each block holds together on Qts, moving mass, cone area and sensitivity. AudioControl measures the 2 ohm and 4 ohm versions as separate drivers, and they differ, so each is aligned on its own figures below.

1.00 cubic feet net on AudioControl's published figures: the SPK-12S2 (single 2 ohm) reads Qtc 0.928 with resonance at 51.6 Hz and half power at 42.1 Hz, and the SPK-12S4 (single 4 ohm) reads Qtc 1.024 with resonance at 56.7 Hz and half power at 44.1 Hz. One cabinet serves both coils. That is AudioControl's own recommended sealed size for this driver, 1 cubic feet, between their 0.85 minimum and 1.5 maximum. That is well above maximally flat: a clear lift near resonance and extra midbass, the way AudioControl voices it in this size.

Trunk-Load Wedge Design Explained

The driver mounts on the vertical trunk-lid-side face and fires rearward into the trunk cavity.

Seat-Side Face Matches Seat Lean

Angled face matches the roughly 20 degree factory seat lean.

Trunk-Lid-Side Face Fires the Woofer

Vertical baffle, cone firing rearward into the trunk cavity.

Trunk Cavity Loading

The trunk acts as an acoustic extension for a smoother presentation.

Preserves Trunk Cargo Space

The wedge tucks against the seat back and the space in front stays usable.

Engineered for the AudioControl Spike SPK-12

Anechoic half power lands at 42.1 Hz on the SPK-12S2 (single 2 ohm) and 44.1 Hz on the SPK-12S4 (single 4 ohm), before any cabin gain. AudioControl publishes the driver displacement, 0.0885 cubic feet, and it is taken out of the net figure.

Alignment Numbers

Driver	System Qtc	fc	F3
Spike SPK-12 SPK-12S2 (single 2 ohm)	Qtc 0.928	51.6 Hz	42.1 Hz
Spike SPK-12 SPK-12S4 (single 4 ohm)	Qtc 1.024	56.7 Hz	44.1 Hz

Mounting Geometry

The baffle is cut to 11.125 in for AudioControl's 12.760 in frame. The rear panel rakes 20 degrees, so the cavity deepens from 7.58 in at the top to 13.04 in at the base, and the 6.14 in motor clears it with 0.75 in to spare. AudioControl prints no bolt circle for the SPK-12, so the baffle ships undrilled with a threaded insert kit and stainless machine screws: set the driver in its recess, mark its holes, drill and press the inserts.

What the Numbers Rest On

Langboard Elite MDF

Premium 3/4 in MDF throughout.

V-Groove and Dado Joinery

CNC cut V-grooves at every panel intersection, sides and brace seated in dados.

Double-Layer 1.5" Front Baffle

Two bonded 3/4 in MDF sheets at the driver face, the outer layer machined as a flush recess.

AudioControl's Published Parameters

SPK-12S2 (single 2 ohm): Fs 37.346 Hz, Qts 0.6718, Qes 0.7362, Qms 7.6824, Vas 25.7006 L, Mms 237.765 g, Bl 11.0117 N/A, Re 1.6 ohm. SPK-12S4 (single 4 ohm): Fs 40.4239 Hz, Qts 0.7297, Qes 0.8207, Qms 6.5823, Vas 27.4067 L, Mms 190.304 g, Bl 13.7286 N/A, Re 3.2 ohm. Cone area 491 cm2. Xmax 14 mm (one-way, method not stated).

Wiring the AudioControl Spike SPK-12 to Your Amplifier

AudioControl sells the SPK-12 as SPK-12S2 (single 2 ohm) and SPK-12S4 (single 4 ohm): the SPK-12S2 (single 2 ohm) is a single 2 ohm coil, a 2 ohm load; the SPK-12S4 (single 4 ohm) is a single 4 ohm coil, a 4 ohm load. A parallel load at or under 1 ohm needs an amplifier rated for it. Confirm the final load against your amplifier's minimum stable impedance before powering the system.

Power handling is 500 watts RMS per driver. Aim for roughly 350 to 500 watts at the impedance you wire.

Built in Tennessee, Backed by Audio Intensity

Cut and assembled in Tullahoma, Tennessee on our own CNC equipment. Finished in plush black carpet with the gloss black acrylic baffle insert, one pre-wired terminal cup, 12 gauge OFC to the driver position. Polyfill wall lining installed. Threaded insert kit and stainless machine screws included (AudioControl publishes no bolt circle). 1 year limited warranty. Enclosure only, the driver is purchased separately. Call or text 931-563-5151.

AudioControl Spike SPK-12: Cut for One Driver

1.00 cubic feet net at Qtc 0.93 to 1.02, F3 42.1 Hz on the SPK-12S2 (single 2 ohm) and 44.1 Hz on the SPK-12S4 (single 4 ohm), cut direct fit and built to order in Tennessee.

Specifications

Specification	Value
Series	Proline X Performance Optimized Wedge
Compatible Driver	AudioControl Spike SPK-12 (SPK-12S2 (single 2 ohm) and SPK-12S4 (single 4 ohm)), quantity 1. Direct fit
Configuration	Single 12 inch, single chamber sealed wedge
Mounting Position	Trunk or cargo area, tall face against the rear seat back
Firing Direction	Rearward into the trunk. Not a down fire design, no feet included
External Width	21.75 in
External Height	15 in at the seat face
External Depth	13.04 in at the base, tapering to 7.58 in at the top
Internal Volume, Gross	1.10 cu ft
Internal Volume, Net Acoustic	1.00 cu ft after the brace and the driver displacement
Driver Mounting Depth	6.14 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment, SPK-12S2 (single 2 ohm)	Qtc 0.928, fc 51.6 Hz, F3 42.1 Hz anechoic
Alignment, SPK-12S4 (single 4 ohm)	Qtc 1.024, fc 56.7 Hz, F3 44.1 Hz anechoic
Woofer Opening	11.125 in, cut for AudioControl's frame
Frame Outer Diameter	12.760 in
Bolt Circle	Not published by AudioControl; threaded insert kit included
Driver Displacement	0.0885 cu ft, AudioControl spec
SPK-12S2 (single 2 ohm) Fs / Qts / Qes / Qms / Vas	37.346 Hz / 0.6718 / 0.7362 / 7.6824 / 25.7006 L
SPK-12S4 (single 4 ohm) Fs / Qts / Qes / Qms / Vas	40.4239 Hz / 0.7297 / 0.8207 / 6.5823 / 27.4067 L
Driver Sd	491 cm2, AudioControl spec
Xmax	14 mm, one-way, method not stated
Driver Power Handling	500 W RMS
Wiring Options	AudioControl sells the SPK-12 as SPK-12S2 (single 2 ohm) and SPK-12S4 (single 4 ohm): the SPK-12S2 (single 2 ohm) is a single 2 ohm coil, a 2 ohm load; the SPK-12S4 (single 4 ohm) is a single 4 ohm coil, a 4 ohm load. A parallel load at or under 1 ohm needs an amplifier rated for it.
Parameter Source	AudioControl Spike Series user manual
Material	Langboard Elite MDF
Construction	CNC cut, V-groove and dado joinery
Panel Thickness	0.75 in
Front Baffle	1.5 in double baffle, outer layer machined as a flush recess
Internal Bracing	Windowed brace, dadoed to the shell
Driver Mounting	Threaded insert kit and stainless machine screws included; inserts set at install, no bolt circle is published
Terminal Cups	One Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC
Acrylic Insert	Gloss black acrylic baffle insert standard; None variant minus $20
Damping	Light polyfill wall lining, does not alter acoustic volume
Carpet	Plush black
Shipping Weight	36 lb
Warranty	1 Year Limited
Built In	Tullahoma, Tennessee

Performance Graphs

Net airspace

1.00

cu ft

System Qtc

0.93–1.02

sealed

Half power

42.1–44.1

Hz · F3

Xmax at

681

W RMS · no filter

With 25 Hz subsonic

717

W RMS · +5%

Amplifier

500

W RMS recommended

This enclosure holds 1.00 cu ft net . In it the AudioControl SPK-12 runs a system Qtc of 0.93–1.02 with half power at 42.1–44.1 Hz, and the cone reaches its 14.0 mm travel limit at 681 W, above the driver’s 500 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 717 W — +37 W, or 5 percent more power for the same 14.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 49.3–50.7

SPK-12S2 · EBP 50.7SPK-12S4 · EBP 49.3

The SPK-12 straddles the boundary at 49.3–50.7 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

1.00 cu ft against a 25.7 L Vas.

α = Vas ÷ Vb = 0.91 · Fc = Fs√(α+1) = 52–57 Hz · Qtc = 0.93–1.02

SPK-12S2 · Qtc 0.93, Fc 52 Hz, F3 42.1 HzSPK-12S4 · Qtc 1.02, Fc 57 Hz, F3 44.1 Hz

The box lifts resonance from 37.3–40.4 Hz free-air to 52–57 Hz and half power lands at 42.1–44.1 Hz, anechoic, before any cabin gain. Parameters are AudioControl’s own user manual for each coil plotted. Only the coils this listing carries are plotted; the other version falls outside a well-behaved sealed alignment in this cabinet.

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 14.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 681–723 W unfiltered → 717–734 W with a 25 Hz subsonic

SPK-12S2 · 681 W, no filterSPK-12S4 · 723 W, no filterSPK-12S2 · 717 W with subsonic at 25 Hz, 24 dB/octSPK-12S4 · 734 W with subsonic at 25 Hz, 24 dB/octXmax 14.0 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 14.0 mm. Unfiltered that is 681 W, reached first at 34 Hz. It sits above the 500 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: stopping the cone wasting travel below the passband lets it take 717 W before hitting the same 14.0 mm. That is 5 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	37.35 / 40.42	Hz	free-air resonance
Qts	0.672 / 0.730		SPK-12S2 / SPK-12S4
Vas	25.70 / 27.41	L	equivalent compliance
Sd	491.0	cm²	effective piston area
Xmax	14	mm	one-way, method not stated
Pe	500	W	continuous RMS
SPL	84.4	dB	1 W / 1 m, derived from T/S

Driver parameters as published by AudioControl user manual. Curves computed against this enclosure’s actual net airspace.

Customer Installs

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.