Proline X CB Pro 12D-P SA12 Professional Series dual 12 ported enclosure for two Sundown Audio SA-12, side port, assembled view and inside plan view

Professional Series Ported Dual 12" Side Port Enclosure, 30" Wide Sundown Audio SA-12 · Dual 12" Ported enclosure

Net volume: 3.92 Cubic Feet
Tuning: 35.0 Hz
Max mounting depth: 8.400 Inches (Sundown Audio Spec)
Cutout: 11.200 Inches (Sundown Audio Spec)
External dimensions: 30.00 Inches W × 16.00 Inches H × 29.62 Inches D
Front baffle: Three 3/4" MDF layers, 2.25" total | Both Woofers Flush-Mounted In The Outer Layer

Request this buildBuilt to order in Tullahoma

SKU CB Pro 12D-P SA12 Dealers: paste this SKU into the order form.

Sundown Audio SA-12Request this build

Alignment: 3.92 cu ft net (1.96 per driver) vented at 35 Hz. F3 29.6 Hz anechoic, 3.44 dB passband ripple
Driver: Pair of Sundown Audio SA-12, 1500 W RMS each, 22.0 mm Xmax, one shared chamber
Build: Custom 30 in wide box, 2.25" three-layer baffle with both woofers flush-mounted, 83.4 sq in slot port out the left side, cross brace behind the magnets, sides recessed 1/2 in, port and excursion gated at 3000 W
Cabinet: 30.00" W x 16.00" H x 29.62" D, 95 lb shipping weight, two threaded insert kits included

Spec of record

Technical specifications

Series	Proline X Professional, Custom Build
Driver-Specific Fitment	Sundown Audio SA-12 D2 (D2)
Enclosure Type	Ported \| Front-Firing Standard Box
External Width	30.00 Inches
External Height	16.00 Inches
External Depth	29.62 Inches
Internal Volume (Gross)	6.14 Cubic Feet
Internal Volume (Net After Displacement)	3.92 Cubic Feet
Port Type	Vertical Slot \| Exits The Left Side At The Rear, Recessed 1/2 In \| One 90 Degree Bend
Port Geometry	5.75 x 14.50 Inches, 83.4 Square Inches, 33.97 Inches Of Path
Port Area	83.4 Square Inches
Port Tuning (Fb)	35.0 Hz
Port Mouth	5.75 x 14.50 Inches On The Left Side, 1/2 In Roundover
Port Air Velocity	21.0 m/s In The Channel, 16.8 m/s At The Mouth, At 3000 W (17.0 m/s Chuff Threshold)
Design Power Basis	3000 W RMS (1.0 x The Driver Rating) For Port Velocity And Excursion
Predicted F3	29.6 Hz (Anechoic)
Passband Ripple	3.44 dB (Anechoic)
Subsonic Filter	28 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs	35.00 Hz
Driver Qts	0.428
Driver Qes / Qms	0.525 / 2.308
Driver Vas	22.188 Liters / 0.784 Cubic Feet
Driver Sd	510.3 Square Centimeters
Driver Mms	369.75 g
Driver BL	22.99
Driver Re	3.4 Ohm
Driver Xmax	22mm (One-Way)
Driver Displacement	0.18 Cubic Feet (Published by Sundown Audio)
Driver Sensitivity	84.5 dB
Driver Power Handling	1500 Watts RMS
Driver Overall Diameter	12.840 Inches (Sundown Audio Spec)
Mounting Depth Required	8.400 Inches (Sundown Audio Spec)
Cutout Diameter	11.200 Inches (Sundown Audio Spec)
Flush Mount Recess	13.750 Inches In The Outer Layer
Material	Langboard Elite 3/4" MDF
Construction	ShopSabre CNC / Windowed Cross Brace 1 In Behind The Motors, Half-Lapped Over A Windowed Centre Brace
Joinery	Dado Joinery (CNC-Cut), Flat Panels
Front Baffle Construction	Three 3/4" MDF layers, 2.25" total \| Both Woofers Flush-Mounted In The Outer Layer
Baffle Layers	3
Acrylic	Glossy Black Sundown Audio Logo Insert, Outer Layer, Top Centre Between The Woofers
Mounting Hardware	Two Threaded Insert Kits Included: Inserts, Drill Bit, 2.5 In Allen-Head Screws, Allen Key, Gasket Tape
Voice Coil Configuration	D2
Terminal Cup	Proline X ABS/Carbon Fiber Composite \| Left Side, Behind The Cross Brace \| 12g OFC Pre-Wired
Damping	None - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power	1050-1500 Watts RMS (Sundown Audio Rated: 1500W RMS)
Carpet Finish	Plush Black
Shipping Weight	95 lb
Shipping	UPS Ground Parcel, Included In The 48 States
Bundle Options	Enclosure Only (Bring Your Own Pair Of Sundown Audio SA-12)
Warranty	2-Year Limited (Enclosure)
Manufactured	Tullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace

3.92

cu ft

Tuning

35.0

Hz · Fb

Half power

29.6

Hz · F3, anechoic

Xmax at

15967

W RMS · 28 Hz subsonic

With NO filter

3783

W RMS · unfiltered

Port

16.8

m/s at the mouth · 3000 W

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 66.7

Sundown Audio SA-12 D2 · EBP 66.7

Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Sundown Audio SA-12 D2 reads 66.7. Ported buys output and low-end reach around tuning; sealed buys a shallower rolloff below it. This cabinet takes the first trade.

02What the box does to it

3.92 cu ft net against a 44.4 L Vas, vented at 35.0 Hz.

Fb = 35.0 Hz · F3 = 29.6 Hz · passband ripple 3.44 dB

Sundown Audio SA-12 D2 · Fb 35.0 Hz, F3 29.6 Hz

Anechoic, before any cabin gain, with the 28 Hz subsonic filter already applied. The vent takes over below 35 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, 3.92 cu ft net vented at 35.0 Hz, against the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SA12) per driver, 2.00 cu ft for the pair.

Ported Fb 35.0 Hz · the 2.00 cu ft sealed box runs Qtc 0.57, Fc 47 Hz

Ported · this cabinet, 3.92 cu ft, Fb 35.0 HzSealed wedge we build, 1.00 cu ft x2, 2.00 cu ft, Qtc 0.57

Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SA12) per driver, 2.00 cu ft for the pair, 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 9.9 dB at its widest and 6.1 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 7.2 dB spread, the 2.00 cu ft sealed box 3.0 dB

Ported, in-car · 7.2 dB spreadSealed wedge we build, 1.00 cu ft x2, 2.00 cu ft, in-car · 3.0 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 7.2 dB of spread against 3.0 dB for the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SA12) per driver, 2.00 cu ft for the pair. The sealed curve is flatter on paper; the ported one trades that for output. Note where the curves cross. Below about 24 Hz the sealed alignment becomes the louder of the two and stays louder all the way down, by up to 4.1 dB: a sealed box rolls off gently into the subsonic region where a vented one falls away steeply once it is below tuning and the vent stops contributing. If the content you are chasing lives below 24 Hz, a sealed alignment reaches further down than this one does. 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 both cones exactly on Sundown's published 22.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off. Every power figure in this section is for the pair, split evenly.

P_Xmax = 15967 W with a 28 Hz subsonic · 3783 W with none → the filter is worth 4.2×

15967 W · subsonic at 28 Hz, 24 dB/oct3783 W · no subsonic filterXmax 22.0 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 22.0 mm. With a 28 Hz subsonic that takes 15967 W, reached first at 28 Hz. Take the filter away and the same cabinet reaches 22.0 mm on 3783 W — the filter is worth 4.2× 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 3783 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 — Sundown rate this one at 3000 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 3000 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.

Before you order

Questions

Why is the port on the side and not the front?

Two SA-12s flush-mounted side by side take the whole 30 inch face: the recesses are half an inch apart and an inch from each edge. Our standard pair is 42 inches wide to fit the slot beside them. Here the 83.4 square inch slot runs along the right side, turns across the back wall and opens on the left side at the rear.

How much room does the port side need?

At least a slot width, about six inches of open air beside the left side of the cabinet. The mouth is 5.75 by 14.50 inches and sits half an inch inside the 30 inch width. If the left side has to go against a wall, tell us before the build and we will mirror it.

Why this airspace and tuning?

Sundown lists 1.75 cubic feet per driver at 35 Hz for the SA-12 ported. This cabinet holds 3.92 cubic feet net, 1.96 per driver, at the same 35 Hz, with F3 at 29.6 Hz and 3.44 dB of ripple. The extra air keeps the port's inside end clear of the cross brace.

Do I need a subsonic filter?

Yes. Set 28 Hz at 24 dB per octave. Below tuning a vented box stops loading the cone, and the filter is what keeps the SA-12s inside their 22 mm of travel at full power.

What power should I run?

The SA-12 is rated 1500 W RMS; plan on 1050 to 1500 W per driver. The port and the cone travel are both checked at 3000 W for the pair: 16.8 metres per second at the mouth against a 17 metre per second chuff threshold, and 9.5 mm of cone travel.

How is it braced?

A windowed cross brace spans side to side one inch behind the motors, half-lapped over a windowed centre brace that runs front to back between the baskets. The port's inside end opens 6.5 inches behind the cross brace, so the vent stays clear of it.

What does the price cover, and how does it ship?

95 lb shipping weight, 30.00" W x 16.00" H x 29.62" D external. Delivery to the 48 states is inside the price and it ships as a UPS parcel. It is a custom build: allow 10 to 15 business days for design and build, and it is final sale except for shipping damage or a build error. Do not add polyfill; it ships dry on purpose.

Are the SA-12s included?

No. This is an enclosure only, cut for a pair of Sundown Audio SA-12s: the 11.2 inch cutouts, the 8.4 inch mounting depth and the alignment all come from Sundown's published parameters. The cutouts and depth clear the SA Classic, v.2 and v.3; the alignment is solved on the v.3. Two threaded insert kits ship with it.

Same series, same size