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Proline X PO 15-S W 9915C sealed wedge, front baffle with gloss black insert and pre-wired leads, 19.12 by 18 inches.
Proline X PO 15-S W 9915C sealed wedge, side profile with recessed terminal cup, 17.72 inch base, 18 inches tall.

Performance Optimized · Datasheet

DD Audio 9915c Box: Sealed 15" Wedge Enclosure Single 15" Sealed enclosure

Net volume
1.40 cu ft
Max mounting depth
10.810 in available, 10.310 in required
Cutout
15.190 in
External dimensions
19.12 in W × 18 in at the seat face H × 17.72 in at the base D
Front baffle
1.5 in, double baffle
Buy at Audio IntensityFactory-direct, ships from Tullahoma
DD Audio 9915cBuy at Audio Intensity
  • Best For: DD Audio 9915c Trunk-Fit Builds
  • Net Volume: 1.40 cu ft (1.82 cu ft Gross)
  • Alignment: Qtc 0.616, fc 52.8 Hz, F3 61.8 Hz
  • Driver Match: DD Audio 9915c (D1 or D2)
  • Construction: 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 9915c, D1 or D2, quantity 1. Direct fit
ConfigurationSingle 15 inch, single chamber sealed wedge
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 Width19.12 in
External Height18 in at the seat face
External Depth17.72 in at the base, tapering to 11.17 in at the top
Internal Volume, Gross1.82 cu ft
Internal Volume, Net Acoustic1.40 cu ft
AlignmentQtc 0.616, fc 52.8 Hz, F3 61.8 Hz anechoic
Driver Cutout15.190 in
Driver Mounting Depth10.810 in available, 10.310 in required
Frame Outer Diameter16.620 in, as published by DD Audio
Driver Displacement0.400 cu ft, as published by DD Audio
Cone Area (derived)1028.9 cm2, from DD's published piston diameter; DD publish no Sd
Power Handling3200 watts RMS
ImpedanceD1: 2 ohms in series or 0.5 ohm in parallel; D2: 4 ohms in series or 1 ohm in parallel
Xmax32 mm one way
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in, double baffle
Internal BracingInternal brace
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
DampingLight polyfill wall lining, does not alter acoustic volume
CarpetPlush black
Shipping Weight40 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.40
cu ft
System Qtc
0.62
sealed
Half power
61.8
Hz · F3
Xmax at
8171
W RMS · no filter
With 25 Hz subsonic
11411
W RMS · +40%
Amplifier
3200
W RMS recommended
This enclosure holds 1.40 cu ft net . In it the DD Audio 9915c runs a system Qtc of 0.62 with half power at 61.8 Hz, and the cone reaches its 32.0 mm travel limit at 8171 W, above the driver’s 3200 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 11411 W — +3240 W, or 40 percent more power for the same 32.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 80.6
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 9915c, D1 or D2 (DD publish one shared table) 80.6
9915c, D1 or D2 (DD publish one shared table) · EBP 80.6
At 80.6 the 9915c sits in the transition band, not the sealed band. That is not a mismatch: a transition motor works in either alignment, and sealed buys a smaller box and a gentler roll-off at the cost of some low-end output. Stage 02 shows what this airspace actually does with it.

02What the box does to it

1.40 cu ft against a 54.4 L Vas.

α = Vas ÷ Vb = 1.37  ·  Fc = Fs√(α+1) = 53 Hz  ·  Qtc = 0.62
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
9915c, D1 or D2 (DD publish one shared table) · Qtc 0.62, Fc 53 Hz, F3 61.8 Hz
The box lifts resonance from 34.3 Hz free-air to 53 Hz and half power lands at 61.8 Hz, anechoic, before any cabin gain. Figures are DD Audio’s own published table for the 9915c, which covers the D1 and D2 alike. DD publish no cone area; the 1028.9 square centimetre figure is derived from their published piston diameter. At 1.40 cubic feet net the 9915c sits at Qtc 0.62: well damped, on the dry side of maximally flat, trading a little low-end reach for control.

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

PXmax = 8171 W unfiltered  →  11411 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 32 40 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 32.0 mm 8171 W reaches Xmax here
9915c, D1 or D2 (DD publish one shared table) · 8171 W, no filter9915c, D1 or D2 (DD publish one shared table) · 11411 W with subsonic at 25 Hz, 24 dB/octXmax 32.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 32.0 mm. Unfiltered that is 8171 W, reached first at 20 Hz. It sits above the 3200 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 11411 W before hitting the same 32.0 mm. That is 40 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs34.32Hzfree-air resonance
Qts0.4009915c, D1 or D2 (DD publish one shared table)
Vas54.38Lequivalent compliance
Sd1028.9cm²effective piston area
Xmax32mmone-way, as DD publish it, with no stated measurement basis
Pe3200Wcontinuous RMS
SPL89.0dB1 W / 1 m, derived from T/S

Driver parameters as published by DD Audio published 9915c specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

1.40 cubic feet net, sized for this driver from DD's published Fs, Qts and Vas. In it the 9915c lands at Qtc 0.616, well damped, on the dry side of flat, with system resonance at 52.8 Hz. Half power lands at 61.8 Hz anechoic, before any cabin gain.

DD publishes no Sd for any of its drivers. The 1028.9 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 9915c in D1 and D2. the D1 is two 1 ohm coils, 2 ohms in series or 0.5 ohm in parallel; the D2 is two 2 ohm coils, 4 ohms in series or 1 ohm in parallel. DD publishes one set of Thiele-Small parameters for the model rather than a set per coil, so this cabinet is the same either way. A parallel load at or under 1 ohm needs an amplifier rated for it.

Measure the base depth. This cabinet is 17.72 inches deep at the trunk floor, 11.17 at the top, and 19.12 wide.

Before you order

Questions

Will this enclosure fit both coil versions of the 9915c?

Yes. DD sells the 9915c in D1 and D2 and publishes one set of Thiele-Small parameters for the model rather than a set per coil, so the cabinet is the same either way. The cutout is 15.190 in and the mounting depth allowance is 10.810 in.

Why 1.40 cubic feet net?

1.40 cubic feet net, sized for this driver from DD's published Fs, Qts and Vas. In it the 9915c lands at Qtc 0.616, well damped, on the dry side of flat, with system resonance at 52.8 Hz. The box is 1.82 cu ft gross before the driver's displacement of 0.400 cu ft, which is DD's own figure.

What amplifier power should I run, and what impedance?

DD rate the 9915c at 3200 watts RMS. DD sells the 9915c in D1 and D2. the D1 is two 1 ohm coils, 2 ohms in series or 0.5 ohm in parallel; the D2 is two 2 ohm coils, 4 ohms in series or 1 ohm in parallel. DD publishes one set of Thiele-Small parameters for the model rather than a set per coil, so this cabinet is the same either way. A parallel load at or under 1 ohm needs an amplifier rated for it. Aim for roughly 2240 to 3200 watts 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 the driver, firing rearward into the trunk cavity.

Where does the cone area figure come from?

DD publishes no Sd for any of its drivers. The 1028.9 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.

What is the expected low-frequency extension?

Half power lands at 61.8 Hz anechoic, before any cabin gain. Qtc is 0.616. These figures exclude cabin gain, which in most vehicles adds real output below 40 Hz. DD publish the 9915c's free-air resonance at 34.32 Hz.

Do I need to add polyfill or damping?

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

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, one side-mounted pre-wired terminal cup and the polyfill lining installed. DD Audio publishes no mounting hole locations for this driver, so the threaded inserts are not pressed before it ships. The threaded insert kit comes in the box instead: inserts sized to the woofer, the correct drill bit, allen-head screws, an allen key and woofer gasket tape. You set them when the woofer goes in.

Same series, same size

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