Professional Series · Datasheet

Professional Series Ported 8" Enclosure Ground Zero GZRW 8XSPL · Single 8" Ported enclosure

Net volume
1.32 Cubic Feet
Tuning
32.5 Hz
Max mounting depth
5.240 Inches (Ground Zero Spec)
Cutout
7.170 Inches (Ground Zero Spec)
External dimensions
30.00 Inches W × 14.00 Inches H × 12.50 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
  • Alignment: 1.32 cu ft net vented at 32.5 Hz. F3 28.2 Hz anechoic, 3.82 dB passband ripple
  • Driver: Ground Zero GZRW 8XSPL SVC or D1, 500 W RMS, 14.0 mm Xmax, 46.00 Hz Fs
  • Build: Front-firing standard box, 2.25" three-layer baffle with the woofer flush-mounted in the outer layer, Ground Zero logo acrylic, dado joinery, 21.9 sq in front slot port beside the woofer with one bend along the back wall, port and excursion gated at 600 W
  • Cabinet: 30.00" W x 14.00" H x 12.50" D, 50 lb, threaded insert kit included

Spec of record

Technical specifications

SeriesProline X Professional
Driver-Specific FitmentGround Zero GZRW 8XSPL SVC or D1 (D1)
Enclosure TypePorted | Front-Firing Standard Box
External Width30.00 Inches
External Height14.00 Inches
External Depth12.50 Inches
Internal Volume (Gross)1.96 Cubic Feet
Internal Volume (Net After Displacement)1.32 Cubic Feet
Port TypeVertical Slot Beside The Woofer | Front Exit | One 90 Degree Bend Along The Back Wall
Port Geometry1.75 x 12.50 Inches, 21.9 Square Inches, 33.83 Inches Of Path
Port Area21.9 Square Inches
Port Tuning (Fb)32.5 Hz
Port Mouth1/2 In Roundover On All Four Edges, 37.1 Square Inches At The Face
Port Air Velocity20.1 m/s In The Channel, 11.8 m/s At The Mouth, At 600 W (17.0 m/s Chuff Threshold)
Design Power Basis600 W RMS (1.2 x The Driver Rating) For Port Velocity And Excursion
Predicted F328.2 Hz (Anechoic)
Passband Ripple3.82 dB (Anechoic)
Subsonic Filter26 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs46.00 Hz
Driver Qts0.360
Driver Qes / Qms0.380 / 8.710
Driver Vas5.000 Liters / 0.177 Cubic Feet
Driver Sd214.0 Square Centimeters
Driver BL14.10
Driver Re1.9 Ohm
Driver Xmax14mm (One-Way)
Driver Displacement0.05 Cubic Feet (Published by Ground Zero)
Driver Sensitivity84.0 dB
Driver Power Handling500 Watts RMS
Driver Overall Diameter8.482 Inches (Ground Zero Spec)
Mounting Depth Required5.240 Inches (Ground Zero Spec)
Cutout Diameter7.170 Inches (Ground Zero Spec)
Flush Mount Recess9.500 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 Ground Zero 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 ConfigurationD1
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 Power350-500 Watts RMS (Ground Zero Rated: 500W RMS)
Carpet FinishPlush Black
Weight50 lb
ShippingUPS Ground Parcel, Included In The 48 States
Bundle OptionsEnclosure Only (Bring Your Own Ground Zero GZRW 8XSPL)
Warranty2-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
1.32
cu ft
Tuning
32.5
Hz · Fb
Half power
28.2
Hz · F3, anechoic
Xmax at
1480
W RMS · 26 Hz subsonic
With NO filter
553
W RMS · unfiltered
Port
11.8
m/s at the mouth · 600 W

01Is this driver right for a ported box?

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

EBP = Fs ÷ Qes = 121.1
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 121.1
Ground Zero GZRW 8XSPL D1 · EBP 121.1
Above 100 the motor is asking for a vent. The Ground Zero GZRW 8XSPL D1 reads 121.1, so a ported load is the alignment it was designed around, not a compromise applied to it.

02What the box does to it

1.32 cu ft net against a 5.0 L Vas, vented at 32.5 Hz.

Fb = 32.5 Hz  ·  F3 = 28.2 Hz  ·  passband ripple 3.82 dB
20 30 50 70 100 150 200 +16 +12 +8 +4 0 −4 −8 −12 −16 −20 −24 −28 FREQUENCY · Hz LEVEL · dB −3 dB Fb 32.5
Ground Zero GZRW 8XSPL D1 · Fb 32.5 Hz, F3 28.2 Hz
Anechoic, before any cabin gain, with the 26 Hz subsonic filter already applied. The vent takes over below 32 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 Ground Zero GZRW 8XSPL D1 — we do not build a sealed enclosure for it and Ground Zero 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 Ground Zero's published 14.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 1480 W with a 26 Hz subsonic  ·  553 W with none  →  the filter is worth 2.7×
20 30 50 70 100 150 200 0 4 8 12 16 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 14.0 mm 1480 W reaches Xmax here
1480 W · subsonic at 26 Hz, 24 dB/oct553 W · no subsonic filterXmax 14.0 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 14.0 mm. With a 26 Hz subsonic that takes 1480 W, reached first at 28 Hz. Take the filter away and the same cabinet reaches 14.0 mm on 553 W — the filter is worth 2.7× 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 553 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 — Ground Zero rate this one at 500 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 500 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 on Ground Zero's own published Fs, Qts, and Vas for the GZRW 8XSPL: 46.00 Hz, 0.3600, and 5.00 litres. It lands at 1.320 cubic feet net, vented at 32.5 Hz, and the model gives back F3 at 28.2 Hz with 3.82 dB of ripple. Ground Zero publishes no vented number of their own for this driver, so there is nothing to check the curve against.

Ground Zero publishes no cone area for this driver. The 214.0 square centimetre Sd behind this alignment, the tuning, the port sizing, and the velocity math, is estimated rather than measured or stated by Ground Zero. Ground Zero also publishes no driver displacement; the 0.049 cubic foot figure I used is estimated too, and it only touches the gross volume number, not the tuning or the port.

Ground Zero calls its excursion spec Max. Excursion and never says what it is measured to. For the GZRW 8XSPL the manual gives a peak-to-peak figure, and I halved it to the 14.0 mm one-way number this box is built around. That halving is the reason this model gets a cabinet at all; most of the rest of the Ground Zero line states no basis for its excursion figure and stays off the bench.

Ground Zero publishes no mounting hole locations for this driver, so I am not pressing the threaded inserts before it ships. The insert kit rides loose in the box; set them at install once the driver is in hand.

The GZRW 8XSPL ships SVC or D1. Wire the SVC straight to your amplifier's rated impedance; wire the D1's two coils in series for 2 ohms or parallel for 0.5 ohm, and a sub-1-ohm parallel load needs an amplifier built for it.

Ground Zero publishes no mounting hole locations for the GZRW 8XSPL, 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. The GZRW 8XSPL does not fit it, so this is the 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 32.5 Hz?

A 0.3600 Qts on 5.00 litres of Vas is a tight, low-compliance motor, and 32.5 Hz brings F3 to 28.2 Hz on 3.82 dB of ripple. At the driver's rated 500 W the port runs 11.8 metres per second through the mouth at 600 W, the reference point the velocity check is measured against. The 214.0 square centimetre Sd behind this solve is not a Ground Zero figure: Ground Zero publishes no cone area for the GZRW 8XSPL, so the number is estimated. Ground Zero also labels its 14.0 mm Xmax figure Max. Excursion without stating a basis; for this model the manual gives a peak-to-peak number, halved here to the one-way figure used in the math, which is the reason this model builds at all while other Ground Zero models with no stated basis are held. 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 GZRW 8XSPL did not clear the channel 28.5 m/s over 0.55 x core 33.8 gate there: the nearest wedge that fits is 30.0 by 9.12 by 13.40 inches with a 13.0 square inch port, and no tuning, width or depth inside that envelope passes. The slot on this box reaches 21.9 square inches. 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 Ground Zero logo acrylic, and a port and excursion budget checked at 600 W. It carries a 2 year warranty against 1.

Threaded inserts or a kit?

Ground Zero does not publish the mounting hole locations for the GZRW 8XSPL, so we cannot install the threaded inserts before it ships. The threaded insert kit comes in the box instead: 8 to 12 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; one kit serves one woofer. A dual cabinet ships two kits.

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 Ground Zero GZRW 8XSPL at 64 percent of its usable travel at 600 W.

Would a sealed box be better for me?

Not one we can show you. We do not build a sealed enclosure for the Ground Zero GZRW 8XSPL and Ground Zero 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 32.5 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, 1.75 inches wide and 21.9 square inches. It runs 7.00 inches to the back wall and turns once along it for 21.33 inches; the fold costs about 1.5 Hz and the port is cut for it. The channel runs at 20.1 metres per second at 600 W, 52 percent of its turbulence limit, and the mouth edges carry a 1/2 inch roundover so the air leaves the face at 11.8 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?

50 lb, 30.00" W x 14.00" H x 12.50" D external. It ships as a UPS parcel; the price includes shipping in the 48 states. Every Professional cabinet is priced the same way, by its size: this one is 3.04 cubic feet outside. Delivery to the 48 states is inside the price; it ships as a 50 lb parcel and checkout adds nothing. Do not add polyfill; it ships dry on purpose.

Is the GZRW 8XSPL included?

No. This is an enclosure only, cut for the Ground Zero GZRW 8XSPL specifically: the 7.170 inch cutout, the 5.240 inch mounting depth allowance and the 1.32 cubic foot alignment all come from Ground Zero's published parameters. It fits both coil versions; the alignment published here is the SVC or D1. Bring your own driver.

Same series, same size

Other Professional Series models