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Performance Optimized · Datasheet

Performance Optimized Wedge Sealed 15" Enclosure | Image Dynamics IDMAX15 V.4 Single 15" Sealed enclosure

Net volume
1.75 cu ft
Max mounting depth
10.866 in required
Cutout
14.764 in
External dimensions
20.17 in W × 18 in at the seat face H × 18.28 in at the base D
Front baffle
1.5 in, double baffle
Buy at Audio Intensity
  • Best For: Image Dynamics IDMAX15 V.4 Trunk-Fit Builds
  • Net Volume: 1.75 cu ft (2.03 cu ft Gross)
  • Alignment: Qtc 1.52 (D2) / 1.63 (D4), F3 33.1 to 33.5 Hz
  • Driver Match: IDMAX15 V.4 (D2 or D4)
  • Watch the impedance: a single D2 parallels to 1 ohm
  • Construction: Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Inserts

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge
Compatible DriverImage Dynamics IDMAX15 V.4, quantity 1. Direct fit, either coil version
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 Width20.17 in
External Height18 in at the seat face
External Depth18.28 in at the base, tapering to 11.73 in at the top
Internal Volume, Gross2.03 cu ft
Internal Volume, Net Acoustic1.75 cu ft
AlignmentQtc 1.521 (D2) / 1.633 (D4), fc 48.0 Hz, F3 33.1 to 33.5 Hz anechoic
Driver Cutout14.764 in
Driver Mounting Depth10.866 in required
Power Handling600 watts RMS
Impedance OptionsD2: 4 ohms series, 1 ohm parallel. D4: 8 ohms series, 2 ohms parallel
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in, double baffle
Internal BracingWindowed C brace
Driver MountingThreaded inserts at every mounting location, stainless machine screws included
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
Weight36.1 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Performance in this enclosure

Net airspace
1.75
cu ft per chamber
System Qtc
1.52–1.63
sealed
Half power
33.1–33.5
Hz · F3
Xmax at
2168
W RMS · no filter
With 25 Hz subsonic
2194
W RMS · +1%
Amplifier
600
W RMS recommended
This enclosure holds 1.75 cu ft net per chamber. In it the Image Dynamics IDMAX15 V.4 runs a system Qtc of 1.52–1.63 with half power at 33.1–33.5 Hz, and the cone reaches its 22.0 mm travel limit at 2168 W, above the driver’s 600 W thermal rating, so heat stops you before travel does. A 25 Hz subsonic filter adds little here: 2194 W against 2168 W, 1 percent. The box already resonates at 48 Hz, so its own rolloff has removed most of what the filter would have stopped.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 22.7–25.0
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 D2 25.0 D4 22.7
D2 · EBP 25.0D4 · EBP 22.7
EBP under 50 means a motor that wants a sealed load. The IDMAX15 sits at 22.7–25.0, inside that band, which is why this is a sealed build rather than a ported one.

02What the box does to it

1.75 cu ft against a 77.5 L Vas.

α = Vas ÷ Vb = 1.56  ·  Fc = Fs√(α+1) = 48 Hz  ·  Qtc = 1.52–1.63
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
D2 · Qtc 1.52, Fc 48 Hz, F3 33.5 HzD4 · Qtc 1.63, Fc 48 Hz, F3 33.1 Hz
The box lifts resonance from 30.0 Hz free-air to 48 Hz and half power lands at 33.1–33.5 Hz, anechoic, before any cabin gain. Image Dynamics publishes a different Vas for the D2 and the D4. A cone and suspension are shared across coil variants, so both cannot be right. The figure here is the row whose moving mass reproduces its own free-air resonance, applied to both coils.

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 22.0 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 2168–2236 W unfiltered  →  2194–2266 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 22.0 mm 2168 W reaches Xmax here
D2 · 2236 W, no filterD4 · 2168 W, no filterD2 · 2266 W with subsonic at 25 Hz, 24 dB/octD4 · 2194 W with subsonic at 25 Hz, 24 dB/octXmax 22.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 22.0 mm. Unfiltered that is 2168 W, reached first at 44 Hz. It sits above the 600 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, and they sit almost on top of the solid ones: 2194 W against 2168 W. At 48 Hz the filter sits well below resonance, where the sealed alignment has already rolled the cone off at 12 dB/oct, so there is little wasted travel left for it to recover. Set it anyway to keep road rumble out of the cone, but do not size the amplifier around it.
ParamValueUnitNote
Fs30.00Hzfree-air resonance
Qts0.950 / 1.020D2 / D4
Vas77.50 / 77.50Lequivalent compliance
Sd935.0cm²effective piston area
Xmax22mmone-way linear travel, 575 ounce motor
Pe600Wcontinuous RMS
SPL84.3dB1 W / 1 m, derived from T/S

Driver parameters as published by loudspeakerdatabase.com. Curves computed against this enclosure’s actual net airspace.

Installer's take

Read the alignment before you read anything else. This is a high-Q sealed box: Qtc 1.52 on the D2 and 1.63 on the D4. That is Image Dynamics' own recommended airspace doing what it does, not a compromise we made. The IDMAX publishes a high Qts, 0.95 and 1.02 on the two coils, and a sealed system Q can never go below the driver's own Qts no matter how big you build.

What that buys you is a rise around 48 Hz and a half power point of 33.1 to 33.5 Hz anechoic, which is lower than a flatter box this size would reach. In a vehicle the cabin does the rest below that. If you want a damped, dry alignment out of an IDMAX, no cabinet that fits a trunk will give it to you.

Check the impedance before you buy the amplifier. A single D2 is 4 ohms in series or 1 ohm in parallel, a D4 is 8 or 2.

Measure the base depth. This cabinet is 18.28 inches deep at the trunk floor, 11.73 at the top, and 20.17 wide. The floor dimension is what decides whether it goes in.

Questions

Will this enclosure fit both the IDMAX15 V.4 D2 and D4?

Yes. Both coil versions share the same frame, the same 14.764 in cutout and the same 10.866 in mounting depth, so the baffle is cut once and fits either. Acoustically they differ more than usual on this driver: Qtc 1.521 on the D2 against 1.633 on the D4, because Image Dynamics publishes a different Vas for each coil.

Why 1.75 cubic feet net?

That is Image Dynamics' published Universal sealed airspace for the IDMAX15 V.4, which is 1.50. This cabinet holds 1.750 because the baffle has to carry the drivers. Gross is 2.03 cu ft before the driver's 0.2599 cu ft displacement. It produces Qtc 1.521 to 1.633, a high-Q sealed alignment rather than a flat one, which is what this driver's own Qts of 0.95 to 1.02 allows.

What amplifier power should I run, and what impedance?

The IDMAX15 V.4 is rated 600 watts RMS each, so 600 across the one driver. On impedance: a D2 gives 4 ohms series, 1 ohm parallel and a D4 gives 8 ohms series, 2 ohms parallel. Aim for roughly 420 to 600 watts at the final wired impedance.

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, which acts as an acoustic extension and smooths the presentation into the cabin.

Why is the front baffle double-layered?

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A subwoofer pushes as hard against its mounting surface as it does against the air, and a single 3/4 inch panel flexes under that load. With 22 mm of one-way travel and 600 watts on tap, that matters here more than it does on a shallow driver.

What is the expected low-frequency extension?

Anechoic F3 lands between 33.1 and 33.5 Hz depending on coil, at Qtc 1.521 to 1.633. That is a peaked alignment, not a flat one: there is a rise around 48 Hz before the rolloff. Those figures exclude cabin gain, which in most vehicles adds meaningful output below 40 Hz.

Do I need to add polyfill or damping?

No. Polyfill is already installed as a light wall lining to control internal reflections, and the quantity is chosen so it does not change the acoustic volume. Do not add more. Packing a sealed box with fill makes it behave as though it were larger, which on this driver would push Qtc the wrong way for no gain in extension.

Is the driver included?

No. This is an enclosure only. You receive the cabinet finished in plush black carpet, with threaded inserts at the driver position, stainless machine screws, one side-mounted pre-wired terminal cup and the polyfill lining already installed.

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