Performance Optimized · Datasheet

Performance Optimized Down Fire Ported 13" Enclosure | JL Audio 13TW5v2 Single 13" Ported enclosure

Net volume
1.54 Cubic Feet
Tuning
32.5 Hz
Max mounting depth
2.638 Inches (JL Audio Spec)
Cutout
12.520 Inches (JL Audio Spec)
External dimensions
31 Inches W × 7.75 Inches H × 18.00 Inches D
Front baffle
Down Firing - Driver Fires Toward Floor
Buy at Audio Intensity
  • Alignment: 1.54 cu ft net vented at 32.5 Hz. F3 32.1 Hz anechoic, 2.36 dB passband ripple
  • Driver: JL Audio 13TW5v2 -4, 600 W RMS, 11.0 mm Xmax, 27.60 Hz Fs
  • Build: Proline X V-groove and dado joinery, L-wrap slot port with a faceted 90 degree bend, double-layer 1.5" baffle, side-mounted terminal cup
  • Cabinet: 31" W x 18.00" D x 7.75" H measured in down fire position, 9.50" tall installed on its feet, square corners, ships dry

Technical specifications

SeriesProline X Performance Optimized Down Fire
Driver-Specific FitmentJL Audio 13TW5v2 -4 (Dual 4 Ohm)
Enclosure TypePorted | Down Fire Geometry | Floor-Coupled
Baffle ConfigurationDown Firing - Driver Fires Toward Floor
External Width31 Inches
External Depth18.00 Inches
External Height7.75 Inches (Cabinet Only)
FeetIncluded - 1.75 Inch Standoff, Required For Down Fire Operation
Installed Height9.50 Inches (7.75 Cabinet Plus 1.75 Feet) - MEASURE AGAINST THIS, NOT THE CABINET HEIGHT
Dimension ReferenceAll External Dimensions Measured In Down Fire Position
Internal Volume (Gross)1.70 Cubic Feet
Internal Volume (Net After Displacement)1.54 Cubic Feet
Port TypeL-Wrap Slot | One Folded Wall | Single Faceted 90 Degree Bend
Port Tuning (Fb)32.5 Hz
Port Channel3.50 x 6.25 Inches (21.9 Square Inches)
Port Path Length28.33 Inches (Centreline)
Port Mouth Area26.5 Square Inches (3.00 Inch Corner Chamfer)
Port Air Velocity15.2 m/s At Tuning (17.0 m/s Chuff Threshold)
Predicted F332.1 Hz (Anechoic)
Passband Ripple2.36 dB (Anechoic)
Subsonic Filter26 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs27.60 Hz
Driver Qts0.530
Driver Qes / Qms0.550 / 10.690
Driver Vas60.300 Liters / 2.129 Cubic Feet
Driver Sd634.0 Square Centimeters
Driver Mms314.00 g
Driver BL18.60
Driver Re3.5 Ohm
Driver Xmax11mm (One-Way)
Driver Displacement0.05 Cubic Feet (Published by JL Audio)
Driver Sensitivity85.7 dB
Driver Power Handling600 Watts RMS
Driver Overall Diameter12.992 Inches (JL Audio Spec)
Mounting Depth Required2.638 Inches (JL Audio Spec)
Cutout Diameter12.520 Inches (JL Audio Spec)
Woofer Ring14.000 Inch OD, Bonded Under The Baffle In A Machined Recess
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Windowed Brace Between Cutout And Port Terminus
JoineryV-Groove and Dado (CNC-Cut)
Front Baffle ConstructionDouble-Layer 1.5" MDF | Outer Layer Flush Recess, Driver Mounts To Inner Layer
Corner ProfileSquare (Down Fire Series Standard)
Mounting Hardware8 x #8-32 Hurricane Nuts Fitted (16 Positions Cut For Driver Orientation) | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual 4 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Side Mounted | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power420-600 Watts RMS (JL Audio Rated: 600W RMS)
Carpet FinishPlush Black
Bundle OptionsEnclosure Only (Bring Your Own JL Audio 13TW5v2)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

Net airspace
1.54
cu ft
Tuning
32.5
Hz · Fb
Half power
32.1
Hz · F3, anechoic
Xmax at
1513
W RMS · 26 Hz subsonic
With NO filter
248
W RMS · unfiltered
Port
15.2
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 = 50.2
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 50.2
JL Audio 13TW5v2-4 · EBP 50.2
Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The JL Audio 13TW5v2-4 reads 50.2. 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

1.54 cu ft net against a 60.3 L Vas, vented at 32.5 Hz.

Fb = 32.5 Hz  ·  F3 = 32.1 Hz  ·  passband ripple 2.36 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 32.5
JL Audio 13TW5v2-4 · Fb 32.5 Hz, F3 32.1 Hz
Anechoic, before any cabin gain, with the 26 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, 1.54 cu ft net vented at 32.5 Hz, against the 0.80 cu ft sealed Down Fire we build for this driver (PO 13-S DF TW5).

Ported Fb 32.5 Hz  ·  the 0.80 cu ft sealed box runs Qtc 1.01, Fc 53 Hz
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +5.4 dB at 36 Hz
Ported · this cabinet, 1.54 cu ft, Fb 32.5 HzSealed Down Fire we build, 0.80 cu ft, Qtc 1.01
Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is the 0.80 cu ft sealed Down Fire we build for this driver (PO 13-S DF TW5), 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 5.4 dB at its widest and 4.5 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 1.5 dB spread, the 0.80 cu ft sealed box 2.9 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +5.4 dB at 36 Hz
Ported, in-car · 1.5 dB spreadSealed Down Fire we build, 0.80 cu ft, in-car · 2.9 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 1.5 dB of spread against 2.9 dB for the 0.80 cu ft sealed Down Fire we build for this driver (PO 13-S DF TW5). 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 JL Audio's published 11.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 1513 W with a 26 Hz subsonic  ·  248 W with none  →  the filter is worth 6.1×
20 30 50 70 100 150 200 0 4 8 12 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 11.0 mm 1513 W reaches Xmax here
1513 W · subsonic at 26 Hz, 24 dB/oct248 W · no subsonic filterXmax 11.0 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 11.0 mm. With a 26 Hz subsonic that takes 1513 W, reached first at 48 Hz. Take the filter away and the same cabinet reaches 11.0 mm on 248 W — the filter is worth 6.1× 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 248 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 — JL Audio rate this one at 600 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 600 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.

Installer's take

2.64 inches. That is the shallowest mounting depth of anything I build a ported box for, and it is a THIRTEEN. The thinPRO12 is 3.00 and it is a twelve. The NB3-10 is 3.00 and it is a ten.

The area is the other half of the story: 634 square centimetres against the 12W1v3's 525 and the IDQS12's 523. Twenty-two percent more cone than the biggest twelve here. A shallow driver loses displacement per stroke because it cannot travel as far, and this one buys it back by being bigger across.

It measures accordingly. 1.48 dB of in-car spread puts it in the top three of the whole range, and it does that on 600 watts, which is not a small motor.

Two things to plan for. It is 18.00 inches deep, tied with the 12W1v3 for the largest cabinet in the line, because a thirteen needs the airspace. And the port runs at 48 percent of its turbulence limit with 15.2 metres per second at the mouth against a 17 threshold. Inside tolerance, not idle.

This is also the only thirteen in the ported range, so if you already own a 13TW5v2 there was previously nothing here for you.

Dual 4 ohm: 2 ohms parallel or 8 ohms series. Subsonic at 26 Hz. Ships dry.

Questions

Why is this enclosure tuned to 32.5 Hz?

Cone area is what moves air, and this one has 22 percent more of it than the biggest twelve in the range. 1.54 cubic feet vented at 32.5 Hz produces 1.48 dB of in-car spread, a top-three result, with 600 watts and 11 mm of travel behind it. The shallow chassis costs displacement per stroke; the extra area gives it straight back. Tuning is chosen for in-car response rather than for an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz, so a box tuned very low reinforces a region the cabin is already reinforcing and leaves 40 to 60 Hz thin. In this cabinet that lands at 1.5 dB of in-car spread across 25 to 60 Hz, which is where kick and bass fundamentals live.

Does this enclosure ship with polyfill?

No, and on this build in particular do not add any. Every sealed Proline X enclosure ships with polyfill pre-installed; a ported one must not, because damping material changes the effective volume the port is tuned against. The port on this cabinet is cut to 28.33 inches of centreline path for 32.5 Hz. Stuff it and you move the tuning without shortening the port, which gives you a mistuned box rather than a bigger-sounding one. The 2.36 dB passband you are paying for depends on it staying dry.

Do I need a subsonic filter?

Yes, at 26 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 JL Audio 13TW5v2 at 63 percent of its usable travel at full rated power; without it there is no meaningful number to quote, because the excursion curve does not converge. On a sealed build a subsonic filter is an improvement. Here it is required equipment.

How much power can I run?

JL Audio rate the 13TW5v2 at 600 W RMS and that is the thermal ceiling. The figures on the Performance Graphs tab are a different quantity: they are mechanical limits, the power at which the cone reaches the end of its linear travel in this specific cabinet. Here the cone sits at 63 percent of usable travel at the driver's own rating, so heat is what stops you, not travel. Final wired impedance and amplifier output are separate questions again.

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 for the same power. The Performance Graphs tab plots this cabinet, 1.54 cubic feet vented at 32.5 Hz, against the 0.80 cu ft sealed Down Fire we build for this driver (PO 13-S DF TW5), so you can judge it yourself.

What is the L-wrap port and why does it matter?

It is a slot port formed by one folded wall: a leg down the long side of the cabinet past the woofer ring, one faceted 90 degree bend, and a leg across the end opening through a chamfered corner. On this cabinet that is 28.33 inches of centreline path and 21.9 square inches of channel, exiting a 26.5 square inch mouth. Air leaves at 15.2 metres per second at tuning against a 17.0 threshold, and the channel runs at 48 percent of its turbulence limit. One wall and one bend rather than a serpentine's three means less wall area inside the box, fewer joints to leak, and one place for flow to separate instead of three.

How is this enclosure built?

V-groove and dado joinery in 0.75 inch Langboard Elite MDF with a double-layer 1.5 inch baffle. The driver mounts to a 14.000 inch ring bonded under the baffle in a machined recess, carrying eight #8-32 hurricane nuts so it threads into steel rather than MDF. A windowed brace sits 2.56 inches clear of the cutout edge and 1.82 inches clear of the port terminus; the window is not weight saving, a solid panel there would split the cavity and make the box a bandpass. Walls seat into dados in both the lid and the baffle. Square corners, plush black carpet, side-mounted terminal cup.

Is the 13TW5v2 included?

No. This is an enclosure only, cut and folded for the JL Audio 13TW5v2 specifically. The 12.520 inch cutout, the 2.638 inch mounting depth allowance and the 1.54 cubic foot alignment all come from JL Audio's published parameters for this exact driver, and the port is sized against its Xmax and power rating. It is not a universal box with a 13 inch hole in it. Bring your own driver.

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