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Professional Series Ported Dual 15" Enclosure Fi Car Audio NEO 3.5 15 · Dual 15" Ported enclosure

Net volume
3.73 Cubic Feet
Tuning
29.0 Hz
Max mounting depth
11.000 Inches (Fi Car Audio Spec)
Cutout
14.125 Inches (Fi Car Audio Spec)
External dimensions
46.00 Inches W × 18.00 Inches H × 18.00 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 NEO 3.5 15Buy at Audio Intensity
  • Alignment: 3.73 cu ft net vented at 29.0 Hz. F3 35.5 Hz anechoic, 0.15 dB passband ripple
  • Driver: Fi Car Audio NEO 3.5 15 D1/D2, 2000 W RMS, 34.0 mm Xmax, 30.40 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, 70.1 sq in front slot port beside the woofer with one bend along the back wall, port and excursion gated at 4000 W
  • Cabinet: 46.00" W x 18.00" H x 18.00" D, 83 lb, threaded insert kit included

Spec of record

Technical specifications

SeriesProline X Professional
Driver-Specific FitmentFi Car Audio NEO 3.5 15 D1/D2 (Dual 1 Ohm or Dual 2 Ohm)
Enclosure TypePorted | Front-Firing Standard Box
External Width46.00 Inches
External Height18.00 Inches
External Depth18.00 Inches
Internal Volume (Gross)6.23 Cubic Feet
Internal Volume (Net After Displacement)3.73 Cubic Feet
Port TypeVertical Slot Beside The Woofer | Front Exit | One 90 Degree Bend Along The Back Wall
Port Geometry4.25 x 16.50 Inches, 70.1 Square Inches, 45.96 Inches Of Path
Port Area70.1 Square Inches
Port Tuning (Fb)29.0 Hz
Port Mouth1/2 In Roundover On All Four Edges, 91.9 Square Inches At The Face
Port Air Velocity21.4 m/s In The Channel, 16.3 m/s At The Mouth, At 4000 W (17.0 m/s Chuff Threshold)
Design Power Basis4000 W RMS (1.0 x The Driver Rating) For Port Velocity And Excursion
Predicted F335.5 Hz (Anechoic)
Passband Ripple0.15 dB (Anechoic)
Subsonic Filter23 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs30.40 Hz
Driver Qts0.430
Driver Qes / Qms0.480 / 7.430
Driver Vas75.020 Liters / 2.649 Cubic Feet
Driver Sd810.0 Square Centimeters
Driver Mms341.00 g
Driver BL21.10
Driver Re1.8 Ohm
Driver Xmax34mm (One-Way)
Driver Displacement0.21 Cubic Feet (Published by Fi Car Audio)
Driver Sensitivity88.3 dB
Driver Power Handling2000 Watts RMS
Driver Overall Diameter15.625 Inches (Fi Car Audio Spec)
Mounting Depth Required11.000 Inches (Fi Car Audio Spec)
Cutout Diameter14.125 Inches (Fi Car Audio Spec)
Flush Mount Recess16.625 Inches In The Outer Layer
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Windowed Brace Front To Back Beside 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 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 Power1400-2000 Watts RMS (Fi Car Audio Rated: 2000W RMS)
Carpet FinishPlush Black
Shipping Weight92 lb
ShippingUPS Ground Parcel, Included In The 48 States
Bundle OptionsEnclosure Only (Bring Your Own Fi Car Audio NEO 3.5 15)
Warranty2-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
3.73
cu ft
Tuning
29.0
Hz · Fb
Half power
35.5
Hz · F3, anechoic
Xmax at
36714
W RMS · 23 Hz subsonic
With NO filter
9183
W RMS · unfiltered
Port
16.3
m/s at the mouth · 4000 W

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 63.3
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 63.3
Fi Car Audio NEO 3.5 15 D2 · EBP 63.3
Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Fi Car Audio NEO 3.5 15 D2 reads 63.3. 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

3.73 cu ft net against a 150.0 L Vas, vented at 29.0 Hz.

Fb = 29.0 Hz  ·  F3 = 35.5 Hz  ·  passband ripple 0.15 dB
20 30 50 70 100 150 200 +4 0 −4 −8 −12 −16 −20 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 29.0
Fi Car Audio NEO 3.5 15 D2 · Fb 29.0 Hz, F3 35.5 Hz
Anechoic, before any cabin gain, with the 23 Hz subsonic filter already applied. The vent takes over below 29 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 NEO 3.5 15 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 both cones exactly on Fi's published 34.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off. Every power figure in this section is for the pair, split evenly.

PXmax = 36714 W with a 23 Hz subsonic  ·  9183 W with none  →  the filter is worth 4.0×
20 30 50 70 100 150 200 0 8 16 24 32 40 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 34.0 mm 36714 W reaches Xmax here
36714 W · subsonic at 23 Hz, 24 dB/oct9183 W · no subsonic filterXmax 34.0 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 34.0 mm. With a 23 Hz subsonic that takes 36714 W, reached first at 21 Hz. Take the filter away and the same cabinet reaches 34.0 mm on 9183 W — the filter is worth 4.0× 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 9183 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 4000 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 4000 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 one for a pair of NEO 3.5 15 in a single shared chamber, which is how a dual ported box should be built: one volume, one port, both drivers loading the same air.

It gets the full Professional treatment, a 2.25 inch three-layer baffle with both woofers flush mounted in the outer layer, and the port on the left of the face.

Wiring is where a dual bites you. These are two 2 ohm coils each, so you can land on 0.5 ohm with all four coils in parallel, 2 ohms as two series pairs in parallel, or 8 ohms with everything in series. Check what your amplifier is rated for before you wire it, not after.

Fi Car Audio publishes no mounting hole locations for the NEO 3.5 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.

It ships dry. Do not add polyfill to a ported box. Set your subsonic filter at 23 Hz.

Before you order

Questions

Why is this enclosure tuned to 29.0 Hz?

Both drivers share one chamber and one port rather than sitting in separate boxes, so the pair works against the whole volume and the port is sized for the pair rather than doubled. The port carries 70.1 square inches of area at 29.0 Hz, and the design power for the velocity and excursion checks is 4000 W for the pair. Passband ripple holds at 0.15 dB across the tuning, with F3 at 35.5 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 NEO 3.5 15 does not fit that envelope at all: no tuning, width or depth inside it carries an 11.00 inch deep 15 inch driver at 2000 W. This box is the chassis with the width, depth and port to carry it. 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 4000 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 NEO 3.5 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 two kits, one per woofer.

Do I need a subsonic filter?

Yes, at 23 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 NEO 3.5 15 at 33 percent of its usable travel at 4000 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 NEO 3.5 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 23 Hz subsonic filter takes over; around 29.0 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, 4.25 inches wide and 70.1 square inches. It runs 10.00 inches to the back wall and turns once along it for 27.96 inches; the fold costs about 1.5 Hz and the port is cut for it. The channel runs at 21.4 metres per second at 4000 W, 47 percent of its turbulence limit, and the mouth edges carry a 1/2 inch roundover so the air leaves the face at 16.3 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?

83 lb, 46.00" W x 18.00" H x 18.00" D external. Every Professional cabinet is priced the same way, by its size: this one is 8.62 cubic feet outside. Delivery to the 48 states is inside the price; it ships as a 83 lb parcel and checkout adds nothing. Do not add polyfill; it ships dry on purpose.

Is the NEO 3.5 15 included?

No. This is an enclosure only, cut for the Fi Car Audio NEO 3.5 15 specifically: the 14.125 inch cutout, the 11.000 inch mounting depth allowance and the 3.73 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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