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Performance Optimized · Datasheet

MTX 3512-02 Box: Ported 12" Wedge Enclosure Single 12" Ported enclosure

Net volume
2.05 Cubic Feet
Tuning
31.5 Hz
Max mounting depth
5.312 Inches (MTX Spec)
Cutout
11.125 Inches (MTX Spec)
External dimensions
30.00 Inches W × 15.50 Inches H × 10.62 Inches / 16.27 Inches D
Front baffle
Vertical Baffle - Driver Fires Rearward Into The Trunk
Buy at Audio IntensityFactory-direct, ships from Tullahoma
  • Alignment: 2.05 cu ft net vented at 31.5 Hz. F3 33.6 Hz anechoic, 2.58 dB passband ripple
  • Driver: MTX 3512-02 S2, 250 W RMS, 8.1 mm Xmax, 30.40 Hz Fs
  • Build: Rear-firing wedge, 20 degree rear rake, V-groove and dado joinery, triangular side-exit slot port with a 1/2" rounded mouth, double 1.5" baffle, side-mounted terminal cup
  • Cabinet: 30.00" W x 15.50" H x 16.27" D at base tapering to 10.62" D at top, 15.5 sq in port, ships dry

Spec of record

Technical specifications

SeriesProline X Performance Optimized Wedge
Driver-Specific FitmentMTX 3512-02 S2 (3512-02 single 2 ohm)
Enclosure TypePorted | Rear-Firing Trunk Wedge
Baffle ConfigurationVertical Baffle - Driver Fires Rearward Into The Trunk
Wedge Angle20 Degrees On The Rear (Seat-Side) Panel
External Width30.00 Inches
External Height15.50 Inches
Top Depth10.62 Inches
Base Depth16.27 Inches
Internal Volume (Gross)2.33 Cubic Feet
Internal Volume (Net After Displacement)2.05 Cubic Feet
Port TypeTriangular Slot | Bottom-Rear Corner | Straight, No Bend | Side Exit
Port GeometryIsosceles, 5.75 Inch Legs, 15.5 Square Inches, 14.79 Inches Long, Side Mouth
Port Tuning (Fb)31.5 Hz
Port MouthTriangle Through Side A, 1/2 In Roundover On All Three Edges, 25.9 Square Inches At The Face
Port ThroatOpen Far End, 13.46 In Gap To Side B, 3/8 In Roundover On The Panel End
Port Air Velocity16.6 m/s In The Channel, 10.0 m/s At The Flared Mouth (17.0 m/s Chuff Threshold)
Predicted F333.6 Hz (Anechoic)
Passband Ripple2.58 dB (Anechoic)
Subsonic Filter25 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs30.40 Hz
Driver Qts0.645
Driver Qes / Qms0.783 / 3.668
Driver Vas73.060 Liters / 2.580 Cubic Feet
Driver Sd573.6 Square Centimeters
Driver Mms173.80 g
Driver BL8.85
Driver Re1.9 Ohm
Driver Xmax8mm (One-Way at one-way, basis not stated)
Excursion Design BasisDerated To 8.1mm For Alignment - MTX Publishes At one-way, basis not stated
Driver Displacement0.08 Cubic Feet (Published by MTX)
Driver Sensitivity86.2 dB
Driver Power Handling250 Watts RMS
Driver Overall Diameter12.375 Inches (MTX Spec)
Mounting Depth Required5.312 Inches (MTX Spec)
Cutout Diameter11.125 Inches (MTX Spec)
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Two Windowed C Braces At The Third Points, Seated On The Port Panel
JoineryV-Groove and Dado (CNC-Cut)
Front Baffle ConstructionDouble-Layer 1.5" MDF | Cosmetic Front Layer Routed For The Acrylic Insert
Mounting HardwareThreaded Inserts At Every Mounting Location | Stainless Steel Machine Screws Included
Voice Coil ConfigurationSingle 2 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Side Mounted, Opposite The Port | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power175-250 Watts RMS (MTX Rated: 250W RMS)
Carpet FinishPlush Black
Shipping Weight59 lb
Bundle OptionsEnclosure Only (Bring Your Own MTX 3512-02)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
2.05
cu ft
Tuning
31.5
Hz · Fb
Half power
33.6
Hz · F3, anechoic
Xmax at
511
W RMS · 25 Hz subsonic
With NO filter
85
W RMS · unfiltered
Port
10.0
m/s at the mouth

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 38.8
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 38.8
MTX 3512-02 · EBP 38.8
Under 50 the raw number leans sealed. The MTX 3512-02 reads 38.8, so this is a ported build against the grain of its own EBP: it works because the alignment is tuned for in-car response rather than for an anechoic curve, and because the cabinet holds port area and volume the driver can actually use.

02What the box does to it

2.05 cu ft net against a 73.1 L Vas, vented at 31.5 Hz.

Fb = 31.5 Hz  ·  F3 = 33.6 Hz  ·  passband ripple 2.58 dB
20 30 50 70 100 150 200 +4 0 −4 −8 −12 −16 −20 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 31.5
MTX 3512-02 · Fb 31.5 Hz, F3 33.6 Hz
Anechoic, before any cabin gain, with the 25 Hz subsonic filter already applied. The vent takes over below 32 Hz and the cone stops doing the work there, which is what holds travel down at the bottom of the passband.

03Perceived Ported vs Sealed

This cabinet, 2.05 cu ft net vented at 31.5 Hz, against MTX Audio's recommended sealed box, 1.00 cu ft.

Ported Fb 31.5 Hz  ·  the 1.00 cu ft sealed box runs Qtc 1.22, Fc 58 Hz
20 30 50 70 100 150 200 +4 0 −4 −8 −12 −16 −20 −24 FREQUENCY · Hz LEVEL · dB +6.5 dB at 25 Hz
Ported · this cabinet, 2.05 cu ft, Fb 31.5 HzMTX Audio's recommended sealed, 1.00 cu ft net, Qtc 1.22
Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is MTX Audio's recommended sealed box, 1.00 cu ft, not this cabinet with the port blocked: two different boxes, because that is the choice a buyer actually has. Across 25 to 60 Hz the vent is worth 6.5 dB at its widest and 5.1 dB on average. This is the anechoic picture, which is not what you hear in a car.

04Real World Ported vs Sealed

The same two boxes with cabin gain applied, 45 Hz corner, 18 dB ceiling.

Flatness across 25–60 Hz: ported 1.0 dB spread, the 1.00 cu ft sealed box 5.3 dB
20 30 50 70 100 150 200 +4 0 −4 −8 −12 −16 −20 −24 FREQUENCY · Hz LEVEL · dB +6.5 dB at 25 Hz
Ported, in-car · 1.0 dB spreadMTX Audio's recommended sealed, 1.00 cu ft net, in-car · 5.3 dB spread
Cabin gain lifts both boxes by the same amount, so the gap between them does not change: what changes is the shape each one ends up with. A car pressurises below roughly 45 Hz, which fills in the sealed box's shallower rolloff and over-drives it where the ported box is already flat. Across 25 to 60 Hz, the band kick and bass fundamentals occupy, this alignment holds 1.0 dB of spread against 5.3 dB for MTX Audio's recommended sealed box, 1.00 cu ft. Flatter is the whole point of tuning this high. The two alignments converge at the bottom of the band rather than crossing cleanly, so there is no meaningful subsonic advantage either way here. Cabin gain here is a house assumption, not a measurement of your vehicle.

05The 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 MTX's published 8.1 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 511 W with a 25 Hz subsonic  ·  85 W with none  →  the filter is worth 6.0×
20 30 50 70 100 150 200 0 4 8 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 8.1 mm 511 W reaches Xmax here
511 W · subsonic at 25 Hz, 24 dB/oct85 W · no subsonic filterXmax 8.1 mm one-way, published
Each trace touches the limit and no further, because each is drawn at the exact power that puts the cone on 8.1 mm. With a 25 Hz subsonic that takes 511 W, reached first at 50 Hz. Take the filter away and the same cabinet reaches 8.1 mm on 85 W — the filter is worth 6.0× the safe power. A vent unloads the cone below tuning, so there is nothing holding it once the box stops loading: on a sealed build a subsonic filter is an improvement, here it is required equipment. The unfiltered trace is still rising where this chart stops at 20 Hz, so treat 85 W as a bound rather than a floor. Every wattage on this page is a MECHANICAL limit, not an electrical one. It is the power at which the cone runs out of linear travel in this cabinet, and nothing more. What the voice coil can dissipate as heat is a separate ceiling set by the driver, not by the box — MTX rate this one at 250 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 250 W as the ceiling and the travel figures above as headroom. Final wired impedance, amplifier output and how long you hold the level are all electrical questions this graph does not answer.

From the shop floor

Installer's take

MTX 3512-02 in the ported wedge: 2.05 cubic feet at 31.5 Hz, 33.6 Hz anechoic.

The port mouth runs about 10 m/s at full power, well clear of chuffing.

MTX publishes no bolt hole circle for any of its subwoofers, so a threaded insert kit and stainless machine screws ship in the box: set the driver, mark its holes, drill and press the inserts.

Rated 250 W RMS by MTX, and this is the single 2 ohm version. It ships dry, no polyfill in a ported box, and set the subsonic filter near 26 Hz.

Before you order

Questions

Why is this enclosure tuned to 31.5 Hz?

We do not list a sealed wedge for this driver. Its Qts is 0.645, and in MTX's own recommended sealed airspace of 1.00 cubic feet it lands at a system Q of 1.22, over the 1.1 ceiling we build sealed cabinets to. Shrinking the box only raises it further, and no sealed enclosure of any size brings it down to a 0.707 alignment. Vented is where this driver works, and here it reaches 33.6 Hz. MTX's own vented recommendation for this driver is 2.32 cubic feet net; this cabinet is 2.05 cubic feet tuned to 31.5 Hz through a 15.5 square inch port, sized against the driver's excursion and port speed at full power. The port runs 16.6 m/s in the channel and 10.0 at the mouth at the 250 W design power, and the cone peaks at 5.7 of its 8.13 mm. Passband ripple is 2.6 dB and the in-car spread from 25 to 60 Hz 1.0 dB. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz. In this cabinet that lands at 1.0 dB of in-car spread across 25 to 60 Hz.

Why the 20 degree wedge, and why rear-firing?

The raked face is the seat side. A factory rear seat back leans about 20 degrees off vertical, so the cabinet sits flat against it and uses floor a square box wastes. The baffle stays vertical and fires rearward into the trunk, which acts as the acoustic extension into the cabin. This one is 16.27 inches deep at the base and 10.62 at the top, 30.00 wide and 15.5 tall.

Do I need a subsonic filter?

Yes, at 25 Hz, 24 dB per octave. Below tuning a vented box stops loading the cone and excursion runs away toward DC. With the filter in place this cabinet puts the MTX 3512-02 at 70 percent of its usable travel at full rated power; without it there is no meaningful number to quote.

How much power can I run, and at what impedance?

MTX rate the 3512-02 at 250 W RMS and that is the thermal ceiling. The Performance Graphs tab shows the mechanical limit, the power at which the cone reaches the end of its travel in this cabinet: here the cone sits at 70 percent of usable travel at the rating, so heat is what stops you, not travel. A D2 coil is 4 ohms in series or 1 ohm in parallel; run series unless the amplifier is rated for 1 ohm. A D4 is 8 series or 2 parallel.

Would a sealed box be better for me?

The two alignments converge at the bottom of the band on this driver rather than crossing cleanly, so there is no meaningful subsonic advantage either way. Above 25 Hz the vent is the louder of the two. The Performance Graphs tab plots this cabinet against MTX Audio's recommended sealed box, 1.00 cu ft.

How does the side port work?

It is a triangular slot in the bottom-rear corner: the floor and the raked back wall are two sides, one bevelled panel is the third. It runs across the cabinet, opens into the box through a 13.46 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 14.79 inches of path and 15.5 square inches of channel running at 16.6 metres per second, 54 percent of its turbulence limit. The three mouth edges are rounded over at 1/2 inch, so the opening at the face is 25.9 square inches and the air leaves it at 10.0 metres per second against the 17.0 threshold where a slot port starts to chuff; the panel's throat end is rounded at 3/8 inch for the same reason. The terminal cup is on the other side.

Does this enclosure ship with polyfill?

No, and do not add any. Every sealed Proline X enclosure ships with polyfill; a ported one must not, because damping changes the effective volume the port is tuned against. The port here is cut to 14.79 inches for 31.5 Hz. Stuff it and you move the tuning without shortening the port.

Is the 3512-02 included?

No. This is an enclosure only, cut for the MTX 3512-02 specifically: the 11.125 inch cutout, the 5.312 inch mounting depth allowance and the 2.05 cubic foot alignment all come from MTX's published parameters. This cabinet is built for the 3512-02 specifically, the single 2 ohm version. MTX gives each coil its own model number and its own published parameters, so the 3512-04 (single 4 ohm) is a different driver with a different Qts and Vas and takes its own enclosure, not this one. Bring your own driver.

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