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Professional Series · Datasheet

Professional Series Ported 15" Enclosure Fi Car Audio Xv4 15 · Single 15" Ported enclosure

Net volume
2.17 Cubic Feet
Tuning
34.5 Hz
Max mounting depth
8.375 Inches (Fi Car Audio Spec)
Cutout
13.875 Inches (Fi Car Audio Spec)
External dimensions
36.00 Inches W × 18.00 Inches H × 14.00 Inches D
Front baffle
Three 3/4" MDF layers, 2.25" total | Woofer Flush-Mounted In The Outer Layer
Buy at Audio IntensityFactory-direct, ships from Tullahoma
Fi Car Audio Xv4 15Buy at Audio Intensity
  • Alignment: 2.17 cu ft net vented at 34.5 Hz. F3 32.1 Hz anechoic, 0.77 dB passband ripple
  • Driver: Fi Car Audio Xv4 15 D1/D2, 1500 W RMS, 27.0 mm Xmax, 39.30 Hz Fs
  • Build: Front-firing standard box, 2.25" three-layer baffle with the woofer flush-mounted in the outer layer, Fi Car Audio logo acrylic, dado joinery, 45.4 sq in front slot port beside the woofer with one bend along the back wall, port and excursion gated at 1500 W
  • Cabinet: 36.00" W x 18.00" H x 14.00" D, 67 lb, threaded insert kit included

Spec of record

Technical specifications

SeriesProline X Professional
Driver-Specific FitmentFi Car Audio Xv4 15 D1/D2 (Dual 1 Ohm or Dual 2 Ohm)
Enclosure TypePorted | Front-Firing Standard Box
External Width36.00 Inches
External Height18.00 Inches
External Depth14.00 Inches
Internal Volume (Gross)3.52 Cubic Feet
Internal Volume (Net After Displacement)2.17 Cubic Feet
Port TypeVertical Slot Beside The Woofer | Front Exit | One 90 Degree Bend Along The Back Wall
Port Geometry2.75 x 16.50 Inches, 45.4 Square Inches, 36.67 Inches Of Path
Port Area45.4 Square Inches
Port Tuning (Fb)34.5 Hz
Port Mouth1/2 In Roundover On All Four Edges, 65.6 Square Inches At The Face
Port Air Velocity19.7 m/s In The Channel, 13.6 m/s At The Mouth, At 1500 W (17.0 m/s Chuff Threshold)
Design Power Basis1500 W RMS (1.0 x The Driver Rating) For Port Velocity And Excursion
Predicted F332.1 Hz (Anechoic)
Passband Ripple0.77 dB (Anechoic)
Subsonic Filter27 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs39.30 Hz
Driver Qts0.550
Driver Qes / Qms0.600 / 6.840
Driver Vas40.000 Liters / 1.413 Cubic Feet
Driver Sd810.0 Square Centimeters
Driver Mms377.40 g
Driver Xmax27mm (One-Way)
Driver Displacement0.18 Cubic Feet (Published by Fi Car Audio)
Driver Sensitivity87.9 dB
Driver Power Handling1500 Watts RMS
Driver Overall Diameter15.500 Inches (Fi Car Audio Spec)
Mounting Depth Required8.375 Inches (Fi Car Audio Spec)
Cutout Diameter13.875 Inches (Fi Car Audio Spec)
Flush Mount Recess16.500 Inches In The Outer Layer
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Two Windowed Braces Front To Back Either Side Of The Woofer
JoineryDado Joinery (CNC-Cut), Flat Panels
Front Baffle ConstructionThree 3/4" MDF layers, 2.25" total | Woofer Flush-Mounted In The Outer Layer
Baffle Layers3
AcrylicGlossy Black Fi Car Audio Logo Insert, Outer Layer, Standard
Mounting HardwareThreaded Insert Kit Included: 8-12 Inserts, Drill Bit, 2.5 In Allen-Head Screws, Allen Key, Gasket Tape
Voice Coil ConfigurationDual 1 or Dual 2 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Back Panel, Terminal-Cup Side | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power1050-1500 Watts RMS (Fi Car Audio Rated: 1500W RMS)
Carpet FinishPlush Black
Shipping Weight75 lb
ShippingUPS Ground Parcel, Included In The 48 States
Bundle OptionsEnclosure Only (Bring Your Own Fi Car Audio Xv4 15)
Warranty2-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
2.17
cu ft
Tuning
34.5
Hz · Fb
Half power
32.1
Hz · F3, anechoic
Xmax at
11734
W RMS · 27 Hz subsonic
With NO filter
2721
W RMS · unfiltered
Port
13.6
m/s at the mouth · 1500 W

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 65.5
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 65.5
Fi Car Audio Xv4 15 D1/D2 · EBP 65.5
Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Fi Car Audio Xv4 15 D1/D2 reads 65.5. 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

2.17 cu ft net against a 40.0 L Vas, vented at 34.5 Hz.

Fb = 34.5 Hz  ·  F3 = 32.1 Hz  ·  passband ripple 0.77 dB
20 30 50 70 100 150 200 +4 0 −4 −8 −12 −16 −20 −24 −28 −32 FREQUENCY · Hz LEVEL · dB −3 dB Fb 34.5
Fi Car Audio Xv4 15 D1/D2 · Fb 34.5 Hz, F3 32.1 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 Fi Car Audio Xv4 15 D1/D2 — we do not build a sealed enclosure for it and Fi 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 Fi's published 27.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 11734 W with a 27 Hz subsonic  ·  2721 W with none  →  the filter is worth 4.3×
20 30 50 70 100 150 200 0 8 16 24 32 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 27.0 mm 11734 W reaches Xmax here
11734 W · subsonic at 27 Hz, 24 dB/oct2721 W · no subsonic filterXmax 27.0 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 27.0 mm. With a 27 Hz subsonic that takes 11734 W, reached first at 26 Hz. Take the filter away and the same cabinet reaches 27.0 mm on 2721 W — the filter is worth 4.3× 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 2721 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 — Fi rate this one at 1500 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 1500 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.

From the shop floor

Installer's take

I built this box for one Xv4 15 on the full Professional chassis: three layers of baffle with the frame flush in the outer one, and a slot port that runs along the back wall to put 34.5 Hz in a 14.0 inch deep box.

One cabinet serves both coils. Fi publishes one parameter set for the dual 1 and dual 2 ohm Xv4 15, so the box is solved on that set and either coil drops in.

Fi publishes no bolt circle, so the box ships with a threaded insert kit rather than pressed inserts.

1500 watts RMS by Fi's rating, and the port is sized for exactly that. The dual 2 ohm wires to 4 ohms in series or 1 ohm in parallel; the dual 1 ohm to 2 ohms series or 0.5 ohm parallel, which few amplifiers tolerate. Fi Car Audio publishes no mounting hole locations for the Xv4 15, so the inserts are not in the baffle when the box arrives. The insert kit is in the box: set the inserts where the woofer's own holes fall, with the drill bit and the 2.5 inch allen-head screws in the kit, and lay the gasket tape before the woofer goes down.

The Performance Optimized wedge is the smaller and cheaper box, and I try it first for every driver. I could not make its port keep up with the Xv4 15: the calmest port that fits that envelope goes noisy at about 1375 watts, under what this coil is rated to take, so I did not sell you that box.

It ships dry. Do not add polyfill to a ported box. Set your subsonic filter at 27 Hz.

Before you order

Questions

Why is this enclosure tuned to 34.5 Hz?

Fi lists no sealed box for the Xv4 at all; it is a ported motor and this is the box it is meant for. The slot is gated at 1500 W, Fi's own rating: the channel runs 19.7 m/s and the mouth 13.6, and the cone peaks at 9.6 of its 27 mm with the subsonic filter in place. Fi's own ported recommendation for the Xv4 15 is 3 to 5 cubic feet at 32 Hz. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz, and this tuning is where that sum comes out flattest across 25 to 60 Hz.

Why is this a Professional build and not a Performance Optimized box?

Every driver is run through the Performance Optimized wedge and down-fire before this chassis; the Professional box is where a driver lands when that smaller envelope, 30 inches wide and 18 inches deep with a triangular side port, cannot give it what it needs at its rated power. The Xv4 15 did not clear the port gate there. The calmest wedge port that fits that envelope is 38.1 square inches at 29.5 by 11.25 by 17.98 inches, and its mouth runs 17.8 metres per second at 1500 W against the 17 metres per second line where a port starts to chuff. That port would stay clean to about 1375 W. The slot on this box reaches 45.4 square inches and holds the mouth at 13.6 metres per second at 1500 W. An under-ported box does not fail quietly. Air speed at the mouth rises with power; past the chuff line the flow turns turbulent and the port is audible on every note. The turbulence also chokes the port, so the box behaves as if it were tuned higher than it is, loses output near tuning, and lets the cone travel further below tuning than the design allows. This chassis is a full-size front-firing box on a 2.25 inch baffle built from three 3/4 inch layers with the woofer flush-mounted in the outer layer, a Fi Car Audio logo acrylic, and a port and excursion budget checked at 1500 W. It carries a 2 year warranty, against 1 year on the Performance Optimized lines.

Threaded inserts or a kit?

Fi Car Audio does not publish the mounting hole locations for the Xv4 15, so we cannot install the threaded inserts before it ships. The threaded insert kit comes in the box instead: inserts sized to the woofer, the correct drill bit, 2.5 inch allen-head screws, an allen key and woofer gasket tape. You set the inserts when you mount the woofer, and this box ships with one kit.

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 Fi Car Audio Xv4 15 at 36 percent of its usable travel at 1500 W.

Would a sealed box be better for me?

Not one we can show you. We do not build a sealed enclosure for the Fi Car Audio Xv4 15 and Fi Car Audio 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 34.5 Hz the vent carries the load and cone travel drops to its minimum, which no sealed alignment can do.

How does the front port work?

It is a vertical slot beside the woofer, the full height of the cavity, 2.75 inches wide and 45.4 square inches. It runs 7.50 inches to the back wall and turns once along it for 22.67 inches; the fold costs about 1.5 Hz and the port is cut for it. The channel runs at 19.7 metres per second at 1500 W, 39 percent of its turbulence limit, and the mouth edges carry a 1/2 inch roundover so the air leaves the face at 13.6 metres per second against the 17 metres per second threshold where a slot starts to chuff.

What does the price cover, and how does it ship?

67 lb, 36.00" W x 18.00" H x 14.00" D external. Every Professional cabinet is priced the same way, by its size: this one is 5.25 cubic feet outside. Delivery to the 48 states is inside the price; it ships as a 67 lb parcel and checkout adds nothing. Do not add polyfill; it ships dry on purpose.

Is the Xv4 15 included?

No. This is an enclosure only, cut for the Fi Car Audio Xv4 15 specifically: the 13.875 inch cutout, the 8.375 inch mounting depth allowance and the 2.17 cubic foot alignment all come from Fi Car Audio's published parameters. It fits both coil versions (D1 and D2), and the cabinet was checked against both. Bring your own driver.

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