Performance Optimized · Datasheet

Performance Optimized Wedge Ported 8" Enclosure | Image Dynamics IDQS8 Single 8" Ported enclosure

Net volume
0.78 Cubic Feet
Tuning
34.0 Hz
Max mounting depth
3.110 Inches (Image Dynamics Spec)
Cutout
7.299 Inches (Image Dynamics Spec)
External dimensions
30.00 Inches W × 11.75 Inches H × 7.25 Inches / 11.53 Inches D
Front baffle
Vertical Baffle - Driver Fires Rearward Into The Trunk
Buy at Audio Intensity
  • Alignment: 0.78 cu ft net vented at 34.0 Hz. F3 29.4 Hz anechoic, 1.83 dB passband ripple
  • Driver: Image Dynamics IDQS8 D2, 125 W RMS, 7.0 mm Xmax, 53.00 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 11.53" D at base tapering to 7.25" D at top, 10.6 sq in port, ships dry

Technical specifications

SeriesProline X Performance Optimized Wedge
Driver-Specific FitmentImage Dynamics IDQS8 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 Depth7.25 Inches
Base Depth11.53 Inches
Internal Volume (Gross)1.04 Cubic Feet
Internal Volume (Net After Displacement)0.78 Cubic Feet
Port TypeTriangular Slot | Bottom-Rear Corner | Straight, No Bend | Side Exit
Port GeometryIsosceles, 4.75 Inch Legs, 10.6 Square Inches, 25.66 Inches Long, Side Mouth
Port Tuning (Fb)34.0 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, 2.59 In Gap To Side B, 3/8 In Roundover On The Panel End
Port Air Velocity14.3 m/s In The Channel, 7.8 m/s At The Flared Mouth (17.0 m/s Chuff Threshold)
Predicted F329.4 Hz (Anechoic)
Passband Ripple1.83 dB (Anechoic)
Subsonic Filter27 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs53.00 Hz
Driver Qts0.980
Driver Qes / Qms1.350 / 3.610
Driver Vas6.418 Liters / 0.227 Cubic Feet
Driver Sd214.0 Square Centimeters
Driver Mms92.00 g
Driver BL10.20
Driver Re4.6 Ohm
Driver Xmax7mm (One-Way)
Driver Displacement0.03 Cubic Feet (Published by Image Dynamics)
Driver Sensitivity81.8 dB
Driver Power Handling125 Watts RMS
Driver Overall Diameter8.346 Inches (Image Dynamics Spec)
Mounting Depth Required3.110 Inches (Image Dynamics Spec)
Cutout Diameter7.299 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 Power87-125 Watts RMS (Image Dynamics Rated: 125W RMS)
Carpet FinishPlush Black
Weight40 lb
Bundle OptionsEnclosure Only (Bring Your Own Image Dynamics IDQS8)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

Net airspace
0.78
cu ft
Tuning
34.0
Hz · Fb
Half power
29.4
Hz · F3, anechoic
Xmax at
218
W RMS · 27 Hz subsonic
With NO filter
110
W RMS · unfiltered
Port
7.8
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 = 39.3
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 39.3
Image Dynamics IDQS8 D2 · EBP 39.3
Under 50 the raw number leans sealed. The Image Dynamics IDQS8 D2 reads 39.3, so this is a ported build against the grain of its own EBP: it works because the alignment is tuned for in-car response rather than for an anechoic curve, and because the cabinet holds port area and volume the driver can actually use.

02What the box does to it

0.78 cu ft net against a 6.4 L Vas, vented at 34.0 Hz.

Fb = 34.0 Hz  ·  F3 = 29.4 Hz  ·  passband ripple 1.83 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 34.0
Image Dynamics IDQS8 D2 · Fb 34.0 Hz, F3 29.4 Hz
Anechoic, before any cabin gain, with the 27 Hz subsonic filter already applied. The vent takes over below 34 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 IDQS8 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 7.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 218 W with a 27 Hz subsonic  ·  110 W with none  →  the filter is worth 2.0×
20 30 50 70 100 150 200 0 4 8 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 7.0 mm 218 W reaches Xmax here
218 W · subsonic at 27 Hz, 24 dB/oct110 W · no subsonic filterXmax 7.0 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 7.0 mm. With a 27 Hz subsonic that takes 218 W, reached first at 28 Hz. Take the filter away and the same cabinet reaches 7.0 mm on 110 W — the filter is worth 2.0× 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 110 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 125 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 125 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

The IDQS8 is a 53 Hz motor with a Qts near 1 on 3.11 inches of mounting depth. Sealed, that is a peaky alignment with no reach; vented at 34 Hz in 0.78 cubic feet the port supplies the bottom octave and the F3 lands at 29.4 Hz on 1.83 dB of ripple. In the car it spreads 5.40 dB across 25 to 60 Hz, because the driver itself is gone before cabin gain arrives. The IDQS10 in this line is the same family with a little more of everything.

7 mm of one-way travel is the whole story on power. The cone uses 5.3 of it at 125 watts with the subsonic filter set, and on material with real bottom end the suspension arrives before the rating does. Set the filter, keep the gain honest. The port is one of the quietest in the line, 14.3 metres per second in the channel and 7.8 at the mouth, so port noise is not a concern here; excursion is.

Questions

Why is this enclosure tuned to 34.0 Hz?

A high Qts shallow eight has no reach of its own; the port supplies it. At 34 Hz the anechoic F3 is 29.4 Hz on 1.83 dB of ripple, and in the car it spreads 5.40 dB across 25 to 60 Hz, because a 53 Hz motor is gone before cabin gain arrives. The port takes 25.66 of the 26.11 inches available and runs at 14.3 metres per second in the channel against a 14.9 limit, 7.8 at the rounded mouth, one of the quietest ports in the line. 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 5.2 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 11.53 inches deep at the base and 7.25 at the top, 30.00 wide and 12 tall.

Do I need a subsonic filter?

Yes, at 27 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 IDQS8 at 76 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 IDQS8 at 125 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 76 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 IDQS8 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 27 Hz subsonic filter takes over; around 34.0 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 2.59 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 25.66 inches of path and 10.6 square inches of channel running at 14.3 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 7.8 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 25.66 inches for 34.0 Hz. Stuff it and you move the tuning without shortening the port.

Is the IDQS8 included?

No. This is an enclosure only, cut for the Image Dynamics IDQS8 specifically: the 7.299 inch cutout, the 3.110 inch mounting depth allowance and the 0.78 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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