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Proline X PO 15D-S W SL715 sealed wedge, front baffle with gloss black insert and pre-wired leads, 36 by 18 inches.
Proline X PO 15D-S W SL715 sealed wedge, side profile with recessed terminal cup, 22.8 inch base, 18 inches tall.

Performance Optimized · Datasheet

Performance Optimized Wedge Sealed Dual 15" Enclosure DD Audio SL715 · Dual 15" Sealed enclosure

Net volume
2.50 cu ft per chamber, 5.00 total
Max mounting depth
16.18 in available, 6.750 in required
Cutout
13.875 in
External dimensions
36.00 in W × 18 in at the seat face H × 22.84 in at the base D
Front baffle
1.5 in, double baffle
Buy at Audio IntensityFactory-direct, ships from Tullahoma
DD Audio SL715Buy at Audio Intensity
  • Best For: Dual DD Audio SL715 Trunk-Fit Builds
  • Net Volume: 2.50 cu ft per chamber, 5.00 total (5.30 cu ft Gross)
  • Alignment: Qtc 0.879, fc 36.9 Hz, F3 31.0 Hz
  • Driver Match: Pair of DD Audio SL715 (matched, D2 or D4)
  • Construction: Dual Chamber | Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Insert Kit included

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge
Compatible DriverDD Audio SL715, D2 or D4, quantity 2. Direct fit
ConfigurationDual 15 inch, two separate sealed chambers
Mounting PositionTrunk or cargo area, tall face against the rear seat back
Firing DirectionRearward into the trunk. Not a down fire design, no feet included
External Width36.00 in
External Height18 in at the seat face
External Depth22.84 in at the base, tapering to 16.29 in at the top
Internal Volume, Gross5.30 cu ft
Internal Volume, Net Acoustic2.50 cu ft per chamber, 5.00 total
AlignmentQtc 0.879, fc 36.9 Hz, F3 31.0 Hz anechoic
Driver Cutout13.875 in
Driver Mounting Depth16.18 in available, 6.750 in required
Frame Outer Diameter15.375 in, as published by DD Audio
Driver Displacement0.090 cu ft each, as published by DD Audio
Cone Area (derived)823.7 cm2, from DD's published piston diameter; DD publish no Sd
Power Handling1000 watts RMS per driver, 2000 total
ImpedanceD2 pair: 2 or 8 ohms; D4 pair: 4 or 1 ohm
Xmax19 mm one way
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in, double baffle
Internal BracingFull-height chamber divider
Driver MountingThreaded insert kit included, NOT pre-installed: DD publish no mounting hole locations
Terminal CupsOne Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC to both chambers
DampingLight polyfill wall lining in both chambers, does not alter acoustic volume
CarpetPlush black
Weight69.9 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
2.50
cu ft per chamber
System Qtc
0.88
sealed
Half power
31.0
Hz · F3
Xmax at
1117
W RMS · no filter
With 25 Hz subsonic
1501
W RMS · +34%
Amplifier
1000
W RMS recommended
This enclosure holds 2.50 cu ft net per chamber. In it the DD Audio SL715 runs a system Qtc of 0.88 with half power at 31.0 Hz, and the cone reaches its 19.0 mm travel limit at 1117 W, above the driver’s 1000 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 1501 W — +384 W, or 34 percent more power for the same 19.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 37.9
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 SL715, D2 or D4 (DD publish one shared table) 37.9
SL715, D2 or D4 (DD publish one shared table) · EBP 37.9
EBP under 50 means a motor that wants a sealed load. The SL715 sits at 37.9, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

2.50 cu ft against a 54.9 L Vas.

α = Vas ÷ Vb = 0.78  ·  Fc = Fs√(α+1) = 37 Hz  ·  Qtc = 0.88
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
SL715, D2 or D4 (DD publish one shared table) · Qtc 0.88, Fc 37 Hz, F3 31.0 Hz
The box lifts resonance from 27.7 Hz free-air to 37 Hz and half power lands at 31.0 Hz, anechoic, before any cabin gain. Figures are DD Audio’s own published table for the SL715, which covers the D2 and D4 alike. DD publish no cone area; the 823.7 square centimetre figure is derived from their published piston diameter. DD’s sealed range for this driver is 1.25 to 2.50 cubic feet, Qtc 1.05 to 0.88; this cabinet is 2.50 cubic feet, the top of that range. At Qtc 0.88 it is punchy, with a clear rise near resonance. Each chamber of this dual holds the same, so per driver it is the single wedge twice over.

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

PXmax = 1117 W unfiltered  →  1501 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 16 20 24 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 19.0 mm 1117 W reaches Xmax here
SL715, D2 or D4 (DD publish one shared table) · 1117 W, no filterSL715, D2 or D4 (DD publish one shared table) · 1501 W with subsonic at 25 Hz, 24 dB/octXmax 19.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 19.0 mm. Unfiltered that is 1117 W, reached first at 22 Hz. It sits above the 1000 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 1501 W before hitting the same 19.0 mm. That is 34 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs27.70Hzfree-air resonance
Qts0.660SL715, D2 or D4 (DD publish one shared table)
Vas54.90Lequivalent compliance
Sd823.7cm²effective piston area
Xmax19mmone-way, as DD publish it, with no stated measurement basis
Pe1000Wcontinuous RMS
SPL83.9dB1 W / 1 m, derived from T/S

Driver parameters as published by DD Audio published SL715 specifications (one table for D2 and D4). Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

2.50 cubic feet net per chamber. DD's own sealed range for the SL715 is 1.25 to 2.5 cubic feet, Qtc 1.05 to 0.88, and a maximally flat box would take 13.14 cubic feet. This cabinet is built at the top of that range, the largest box DD recommend for the SL715, which gives it the lowest Qtc and deepest reach DD's range allows. In 2.50 cubic feet the SL715 lands at Qtc 0.879, punchy, with a clear rise near resonance and extra midbass, with system resonance at 36.9 Hz. Half power lands at 31.0 Hz anechoic, before any cabin gain.

DD publishes no Sd for any of its drivers. The 823.7 square centimetre figure behind this alignment is derived from DD's own published piston diameter, which they define as measured halfway across the surround, the convention Sd itself is defined from. DD publishes no Mms, Cms or DC resistance either.

DD publishes no mounting hole locations, so the inserts are not in the baffle when the box arrives. The insert kit is in the box: set them where the woofer's own holes fall, with the drill bit and screws in the kit, and lay the gasket tape before the woofer goes down.

DD sells the SL715 in D2 and D4, and a matched pair should share a coil. A D2 pair wires each woofer's coils in series (4 ohms) and the two woofers in parallel for 2 ohms, or everything in series for 8 ohms. A D4 pair wires each woofer's coils in series (8 ohms) and the two woofers in parallel for 4 ohms, or each woofer's coils in parallel (2 ohms) and the two woofers in parallel for 1 ohm. A 1 ohm load needs an amplifier rated 1 ohm stable; if yours is not, use the higher option. DD publishes one set of Thiele-Small parameters for the model, so the cabinet is the same for either coil.

Measure the base depth. This cabinet is 22.84 inches deep at the trunk floor, 16.29 at the top, and 36.00 wide. At 36.00 in wide the volume has to come from depth, so the base runs 22.84 in deep on an 18 in tall cabinet.

Before you order

Questions

Will this enclosure fit two SL715, in either coil version?

Yes. DD sells the SL715 in D2 and D4 on the same frame, so both fit mechanically. Both positions are CNC cut to 13.875 in with 16.18 in of mounting depth available against the 6.750 in DD specify. Run a matched pair, both D2 or both D4.

Why 2.50 cubic feet net per driver?

2.50 cubic feet net per chamber. DD's own sealed range for the SL715 is 1.25 to 2.5 cubic feet, Qtc 1.05 to 0.88, and a maximally flat box would take 13.14 cubic feet. This cabinet is built at the top of that range, the largest box DD recommend for the SL715, which gives it the lowest Qtc and deepest reach DD's range allows. In 2.50 cubic feet the SL715 lands at Qtc 0.879, punchy, with a clear rise near resonance and extra midbass, with system resonance at 36.9 Hz. The cabinet is 5.30 cu ft gross before two drivers' displacement of 0.090 cu ft each, DD's own figure.

What amplifier power should I run, and what impedance?

DD rate the SL715 at 1000 watts RMS each, 2000 across the pair. DD sells the SL715 in D2 and D4, and a matched pair should share a coil. A D2 pair wires each woofer's coils in series (4 ohms) and the two woofers in parallel for 2 ohms, or everything in series for 8 ohms. A D4 pair wires each woofer's coils in series (8 ohms) and the two woofers in parallel for 4 ohms, or each woofer's coils in parallel (2 ohms) and the two woofers in parallel for 1 ohm. A 1 ohm load needs an amplifier rated 1 ohm stable; if yours is not, use the higher option. DD publishes one set of Thiele-Small parameters for the model, so the cabinet is the same for either coil. Aim for roughly 1400 to 2000 watts total at the impedance you wire.

How does a wedge enclosure improve the sound in a trunk installation?

The angled seat-side face matches the roughly 20 degree lean of a factory rear seat, so the cabinet sits flat against it instead of leaving a wasted triangle. The vertical trunk-lid-side face carries both drivers, firing rearward into the trunk cavity.

Why two separate chambers instead of one shared one?

Two drivers sharing one sealed volume load each other, and a fault in one changes how the other behaves. Here a full-height divider gives each SL715 its own 2.50 cubic feet, so each runs the single-driver alignment, Qtc 0.879, regardless of what the other is doing.

What is the expected low-frequency extension?

Half power lands at 31.0 Hz anechoic, before any cabin gain. Qtc is 0.879 in each chamber. These figures exclude cabin gain, which in most vehicles adds real output below 40 Hz. DD publish the SL715's free-air resonance at 27.70 Hz.

Do I need to add polyfill or damping?

No. Polyfill is already installed in both chambers as a light wall lining and the quantity is chosen so it does not change the acoustic volume. Do not add more.

Are the drivers included, and are the threaded inserts installed?

No drivers: this is an enclosure only, bring your own matched pair. You receive the cabinet finished in plush black carpet, one side-mounted pre-wired terminal cup feeding both chambers and the polyfill lining installed. DD Audio publishes no mounting hole locations for this driver, so the threaded inserts are not pressed at either position before it ships. The threaded insert kit comes in the box instead: inserts sized to the woofers for both positions, the correct drill bit, allen-head screws, an allen key and woofer gasket tape. You set them when the woofers go in.

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