Performance Optimized · Datasheet

Performance Optimized Wedge Ported 8" Enclosure | Image Dynamics ID8 V4 Single 8" Ported enclosure

Net volume
0.84 Cubic Feet
Tuning
33.0 Hz
Max mounting depth
4.370 Inches (Image Dynamics Spec)
Cutout
7.087 Inches (Image Dynamics Spec)
External dimensions
30.00 Inches W × 11.75 Inches H × 7.75 Inches / 12.03 Inches D
Front baffle
Vertical Baffle - Driver Fires Rearward Into The Trunk
Buy at Audio Intensity
  • Alignment: 0.84 cu ft net vented at 33.0 Hz. F3 31.3 Hz anechoic, 1.08 dB passband ripple
  • Driver: Image Dynamics ID8 V4 D2, 150 W RMS, 12.5 mm Xmax, 31.00 Hz Fs
  • Build: Rear-firing wedge, 20 degree rear rake, V-groove and dado joinery, triangular side-exit slot port with a 1/2" rounded mouth, double 1.5" baffle, side-mounted terminal cup
  • Cabinet: 30.00" W x 11.75" H x 12.03" D at base tapering to 7.75" D at top, 10.6 sq in port, ships dry

Technical specifications

SeriesProline X Performance Optimized Wedge
Driver-Specific FitmentImage Dynamics ID8 V4 D2 (Dual 2 Ohm)
Enclosure TypePorted | Rear-Firing Trunk Wedge
Baffle ConfigurationVertical Baffle - Driver Fires Rearward Into The Trunk
Wedge Angle20 Degrees On The Rear (Seat-Side) Panel
External Width30.00 Inches
External Height11.75 Inches
Top Depth7.75 Inches
Base Depth12.03 Inches
Internal Volume (Gross)1.12 Cubic Feet
Internal Volume (Net After Displacement)0.84 Cubic Feet
Port TypeTriangular Slot | Bottom-Rear Corner | Straight, No Bend | Side Exit
Port GeometryIsosceles, 4.75 Inch Legs, 10.6 Square Inches, 25.06 Inches Long, Side Mouth
Port Tuning (Fb)33.0 Hz
Port MouthTriangle Through Side A, 1/2 In Roundover On All Three Edges, 19.4 Square Inches At The Face
Port ThroatOpen Far End, 3.19 In Gap To Side B, 3/8 In Roundover On The Panel End
Port Air Velocity15.2 m/s In The Channel, 8.3 m/s At The Flared Mouth (17.0 m/s Chuff Threshold)
Predicted F331.3 Hz (Anechoic)
Passband Ripple1.08 dB (Anechoic)
Subsonic Filter26 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs31.00 Hz
Driver Qts0.460
Driver Qes / Qms0.520 / 4.010
Driver Vas24.248 Liters / 0.856 Cubic Feet
Driver Sd241.0 Square Centimeters
Driver Mms78.60 g
Driver BL14.90
Driver Re3.8 Ohm
Driver Xmax12mm (One-Way)
Driver Displacement0.05 Cubic Feet (Published by Image Dynamics)
Driver Sensitivity86.7 dB
Driver Power Handling150 Watts RMS
Driver Overall Diameter8.268 Inches (Image Dynamics Spec)
Mounting Depth Required4.370 Inches (Image Dynamics Spec)
Cutout Diameter7.087 Inches (Image Dynamics Spec)
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Two Windowed C Braces At The Third Points, Seated On The Port Panel
JoineryV-Groove and Dado (CNC-Cut)
Front Baffle ConstructionDouble-Layer 1.5" MDF | Cosmetic Front Layer Routed For The Acrylic Insert
Mounting HardwareThreaded Inserts At Every Mounting Location | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual 2 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Side Mounted, Opposite The Port | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power105-150 Watts RMS (Image Dynamics Rated: 150W RMS)
Carpet FinishPlush Black
Weight40 lb
Bundle OptionsEnclosure Only (Bring Your Own Image Dynamics ID8 V4)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

Net airspace
0.84
cu ft
Tuning
33.0
Hz · Fb
Half power
31.3
Hz · F3, anechoic
Xmax at
569
W RMS · 26 Hz subsonic
With NO filter
104
W RMS · unfiltered
Port
8.3
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 = 59.6
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 59.6
Image Dynamics ID8 V4 D2 · EBP 59.6
Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Image Dynamics ID8 V4 D2 reads 59.6. 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

0.84 cu ft net against a 24.2 L Vas, vented at 33.0 Hz.

Fb = 33.0 Hz  ·  F3 = 31.3 Hz  ·  passband ripple 1.08 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 33.0
Image Dynamics ID8 V4 D2 · Fb 33.0 Hz, F3 31.3 Hz
Anechoic, before any cabin gain, with the 26 Hz subsonic filter already applied. The vent takes over below 33 Hz and the cone stops doing the work there, which is what holds travel down at the bottom of the passband.

03Ported vs Sealed

No sealed comparison is shown for this driver.

A ported-versus-sealed chart is only worth reading against a sealed box someone would actually build: the one we make for the driver, or the one its maker recommends. Neither exists for the Image Dynamics ID8 V4 D2 — we do not build a sealed enclosure for it and Image Dynamics publish no sealed volume for it — so rather than compare this cabinet against itself stuffed and sealed, a box no one would build, the comparison is left out.

04The 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 Image Dynamics's published 12.5 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 569 W with a 26 Hz subsonic  ·  104 W with none  →  the filter is worth 5.5×
20 30 50 70 100 150 200 0 4 8 12 16 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 12.5 mm 569 W reaches Xmax here
569 W · subsonic at 26 Hz, 24 dB/oct104 W · no subsonic filterXmax 12.5 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 12.5 mm. With a 26 Hz subsonic that takes 569 W, reached first at 24 Hz. Take the filter away and the same cabinet reaches 12.5 mm on 104 W — the filter is worth 5.5× 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 104 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 — Image Dynamics rate this one at 150 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 150 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

This cabinet is cut for the D2 coil and built on the D2 figures. Image Dynamics' published D4 parameters do not survive their own arithmetic: Mms and Cms imply a 45 Hz resonance against a printed 31, a 47 percent miss. The D2 reproduces its own Fs within 7 percent, so that is the column I used. The D4 still fits mechanically.

A 0.46 Qts on 24 litres tunes cleanly at 33 Hz and graphs flat, 1.08 dB of ripple, 2.54 dB in the car against 3.78 for the Down Fire version. 150 watts is the ceiling and the cone uses 6.4 of its 12.5 mm at that power with the 26 Hz filter set. The base is a quarter inch deeper than the 11.75 inch height.

Questions

Why is this enclosure tuned to 33.0 Hz?

A 0.46 Qts on 24 litres tunes cleanly a little above its resonance and graphs flat when it does: 1.08 dB of anechoic ripple with an F3 of 31.3 Hz, and 2.54 dB of in-car spread across 25 to 60 Hz; the Down Fire version of this driver reads 3.78 in the car. The port uses 25.06 of 26.11 inches of path and runs at 15.2 metres per second in the channel against a 16.2 limit, 8.3 at the mouth. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz. In this cabinet that lands at 2.6 dB of in-car spread across 25 to 60 Hz.

Why the 20 degree wedge, and why rear-firing?

The raked face is the seat side. A factory rear seat back leans about 20 degrees off vertical, so the cabinet sits flat against it and uses floor a square box wastes. The baffle stays vertical and fires rearward into the trunk, which acts as the acoustic extension into the cabin. This one is 12.03 inches deep at the base and 7.75 at the top, 30.00 wide and 12 tall.

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 Image Dynamics ID8 V4 at 51 percent of its usable travel at full rated power; without it there is no meaningful number to quote.

How much power can I run, and at what impedance?

Image Dynamics rate the ID8 V4 at 150 W RMS and that is the thermal ceiling. The Performance Graphs tab shows the mechanical limit, the power at which the cone reaches the end of its travel in this cabinet: here the cone sits at 51 percent of usable travel at the rating, so heat is what stops you, not travel. A D2 coil is 4 ohms in series or 1 ohm in parallel; run series unless the amplifier is rated for 1 ohm. A D4 is 8 series or 2 parallel.

Would a sealed box be better for me?

Not one we can show you. We do not build a sealed enclosure for the Image Dynamics ID8 V4 and Image Dynamics publish no sealed volume for it, so the Performance Graphs tab carries no ported-versus-sealed chart: the only sealed box left to plot would be this cabinet stuffed and sealed, which nobody would build, and a comparison against it would tell you nothing you could buy. What a vented box gives up is the region below tuning, where the cone unloads and the 26 Hz subsonic filter takes over; around 33.0 Hz the vent carries the load and cone travel drops to its minimum, which no sealed alignment can do.

How does the side port work?

It is a triangular slot in the bottom-rear corner: the floor and the raked back wall are two sides, one bevelled panel is the third. It runs across the cabinet, opens into the box through a 3.19 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 25.06 inches of path and 10.6 square inches of channel running at 15.2 metres per second, 52 percent of its turbulence limit. The three mouth edges are rounded over at 1/2 inch, so the opening at the face is 19.4 square inches and the air leaves it at 8.3 metres per second against the 17.0 threshold where a slot port starts to chuff; the panel's throat end is rounded at 3/8 inch for the same reason. The terminal cup is on the other side.

Does this enclosure ship with polyfill?

No, and do not add any. Every sealed Proline X enclosure ships with polyfill; a ported one must not, because damping changes the effective volume the port is tuned against. The port here is cut to 25.06 inches for 33.0 Hz. Stuff it and you move the tuning without shortening the port.

Is the ID8 V4 included?

No. This is an enclosure only, cut for the Image Dynamics ID8 V4 specifically: the 7.087 inch cutout, the 4.370 inch mounting depth allowance and the 0.84 cubic foot alignment all come from Image Dynamics's published parameters. It fits both coil versions; the alignment published here is the D2. Bring your own driver.

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