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Professional Series · Datasheet

Professional Series Ported 18" Enclosure Ampere Audio AA-3.0 18 · Single 18" Ported enclosure

Net volume
4.12 Cubic Feet
Tuning
35.5 Hz
Max mounting depth
12.500 Inches (Ampere Audio Spec)
Cutout
16.875 Inches (Ampere Audio Spec)
External dimensions
36.00 Inches W × 21.00 Inches H × 20.00 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
Ampere Audio AA-3.0 18Buy at Audio Intensity
  • Alignment: 4.12 cu ft net vented at 35.5 Hz. F3 29.2 Hz anechoic, 5.40 dB passband ripple
  • Driver: Ampere Audio AA-3.0 18 D1/D2, 2000 W RMS, 29.0 mm Xmax, 25.00 Hz Fs
  • Build: Front-firing standard box, 2.25" three-layer baffle with the woofer flush-mounted in the outer layer, Ampere Audio logo acrylic, dado joinery, 92.6 sq in front slot port beside the woofer with one bend along the back wall, port and excursion gated at 2400 W
  • Cabinet: 36.00" W x 21.00" H x 20.00" D, 83 lb, threaded insert kit included

Spec of record

Technical specifications

SeriesProline X Professional
Driver-Specific FitmentAmpere Audio AA-3.0 18 D1/D2 (Dual 1 Ohm or Dual 2 Ohm)
Enclosure TypePorted | Front-Firing Standard Box
External Width36.00 Inches
External Height21.00 Inches
External Depth20.00 Inches
Internal Volume (Gross)6.43 Cubic Feet
Internal Volume (Net After Displacement)4.12 Cubic Feet
Port TypeVertical Slot Beside The Woofer | Front Exit | One 90 Degree Bend Along The Back Wall
Port Geometry4.75 x 19.50 Inches, 92.6 Square Inches, 34.61 Inches Of Path
Port Area92.6 Square Inches
Port Tuning (Fb)35.5 Hz
Port Mouth1/2 In Roundover On All Four Edges, 117.9 Square Inches At The Face
Port Air Velocity17.1 m/s In The Channel, 13.4 m/s At The Mouth, At 2400 W (17.0 m/s Chuff Threshold)
Design Power Basis2400 W RMS (1.2 x The Driver Rating) For Port Velocity And Excursion
Predicted F329.2 Hz (Anechoic)
Passband Ripple5.40 dB (Anechoic)
Subsonic Filter28 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs25.00 Hz
Driver Qts0.500
Driver Qes / Qms0.580 / 3.870
Driver Vas97.300 Liters / 3.436 Cubic Feet
Driver Sd1134.1 Square Centimeters
Driver Mms760.80 g
Driver BL27.30
Driver Re3.6 Ohm
Driver Xmax29mm (One-Way)
Driver Displacement0.26 Cubic Feet (Published by Ampere Audio)
Driver Sensitivity86.1 dB
Driver Power Handling2000 Watts RMS
Driver Overall Diameter18.500 Inches (Ampere Audio Spec)
Mounting Depth Required12.500 Inches (Ampere Audio Spec)
Cutout Diameter16.875 Inches (Ampere Audio Spec)
Flush Mount Recess19.500 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 Ampere 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 (Ampere Audio Rated: 2000W RMS)
Carpet FinishPlush Black
Shipping Weight91 lb
ShippingUPS Ground Parcel, Included In The 48 States
Bundle OptionsEnclosure Only (Bring Your Own Ampere Audio AA-3.0 18)
Warranty2-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
4.12
cu ft
Tuning
35.5
Hz · Fb
Half power
29.2
Hz · F3, anechoic
Xmax at
24441
W RMS · 28 Hz subsonic
With NO filter
3806
W RMS · unfiltered
Port
13.4
m/s at the mouth · 2400 W

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 43.1
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 43.1
Ampere Audio AA-3.0 18 D2 · EBP 43.1
Under 50 the raw number leans sealed. The Ampere Audio AA-3.0 18 D2 reads 43.1, 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

4.12 cu ft net against a 97.3 L Vas, vented at 35.5 Hz.

Fb = 35.5 Hz  ·  F3 = 29.2 Hz  ·  passband ripple 5.40 dB
20 30 50 70 100 150 200 +8 +4 0 −4 −8 −12 −16 −20 −24 −28 −32 FREQUENCY · Hz LEVEL · dB −3 dB Fb 35.5
Ampere Audio AA-3.0 18 D2 · Fb 35.5 Hz, F3 29.2 Hz
Anechoic, before any cabin gain, with the 28 Hz subsonic filter already applied. The vent takes over below 36 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 Ampere Audio AA-3.0 18 D2 — we do not build a sealed enclosure for it and Ampere 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 Ampere's published 29.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 24441 W with a 28 Hz subsonic  ·  3806 W with none  →  the filter is worth 6.4×
20 30 50 70 100 150 200 0 8 16 24 32 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 29.0 mm 24441 W reaches Xmax here
24441 W · subsonic at 28 Hz, 24 dB/oct3806 W · no subsonic filterXmax 29.0 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 29.0 mm. With a 28 Hz subsonic that takes 24441 W, reached first at 27 Hz. Take the filter away and the same cabinet reaches 29.0 mm on 3806 W — the filter is worth 6.4× 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 3806 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 — Ampere rate this one at 2000 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 2000 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 AA-3.0 18 on the full Professional chassis: three layers of baffle with the frame flush in the outer one, the Ampere acrylic beside it, and a slot port that turns once along the back wall so a 35.5 Hz tuning fits a 20 inch deep box.

It is an even response: 5.7 dB of spread from 25 to 60 Hz in a car.

Ampere print no bolt circle, so a threaded insert kit ships in the box. The figures are solved on Ampere's dual 2 ohm row. The dual 1 ohm version shares the frame, cutout and mounting depth and fits the same cabinet; its own table reads a touch lower in Q (Qts 0.46 against 0.5), so it sits a little tighter near tuning in this box.

Rated 2000 W RMS by Ampere. It ships dry; do not add polyfill to a ported box. Set your subsonic filter near 30 Hz.

Ampere Audio publishes no mounting hole locations for the AA-3.0 18, 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.

Before you order

Questions

Why is this enclosure tuned to 35.5 Hz?

Sealed, the AA-3.0 18 is listed in our wedge at 2.96 cubic feet, Qtc 0.68 to 0.73, half power 39 Hz. Vented it goes far deeper. The port runs 17.1 m/s in the channel and 13.4 at the mouth at 2400 W, 1.2 times Ampere's rating, and the cone peaks at 9.1 of its 29 mm. Passband ripple is 5.4 dB and the in-car spread from 25 to 60 Hz 5.7 dB. 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 AA-3.0 18 does not fit that envelope at all: no tuning, width or depth inside it carries a 12.50 inch deep 18 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, an Ampere Audio logo acrylic, and a port and excursion budget checked at 2400 W. It carries a 2 year warranty, against 1 year on the Performance Optimized lines.

Threaded inserts or a kit?

Ampere Audio does not publish the mounting hole locations for the AA-3.0 18, 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 28 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 Ampere Audio AA-3.0 18 at 31 percent of its usable travel at 2400 W.

Would a sealed box be better for me?

Not one we can show you. We do not build a sealed enclosure for the Ampere Audio AA-3.0 18 and Ampere 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 28 Hz subsonic filter takes over; around 35.5 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, 4.75 inches wide and 92.6 square inches. It runs 11.50 inches to the back wall and turns once along it for 14.61 inches; the fold costs about 1.5 Hz and the port is cut for it. The channel runs at 17.1 metres per second at 2400 W, 20 percent of its turbulence limit, and the mouth edges carry a 1/2 inch roundover so the air leaves the face at 13.4 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, 36.00" W x 21.00" H x 20.00" D external. Every Professional cabinet is priced the same way, by its size: this one is 8.75 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 AA-3.0 18 included?

No. This is an enclosure only, cut for the Ampere Audio AA-3.0 18 specifically: the 16.875 inch cutout, the 12.500 inch mounting depth allowance and the 4.12 cubic foot alignment all come from Ampere 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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