Performance Optimized · Datasheet

Performance Optimized Down Fire Ported 10" Enclosure | Rockford Fosgate R2SD4-10 Single 10" Ported enclosure

Net volume
1.26 Cubic Feet
Tuning
35.5 Hz
Max mounting depth
3.417 Inches (Rockford Fosgate Spec)
Cutout
9.125 Inches (Rockford Fosgate Spec)
External dimensions
31 Inches W × 7.75 Inches H × 15.00 Inches D
Front baffle
Down Firing - Driver Fires Toward Floor
Buy at Audio Intensity
  • Alignment: 1.26 cu ft net vented at 35.5 Hz. F3 31.7 Hz anechoic, 2.49 dB passband ripple
  • Driver: Rockford Fosgate R2SD4-10 D4, 200 W RMS, 8.0 mm Xmax, 39.30 Hz Fs
  • Build: Proline X V-groove and dado joinery, L-wrap slot port with a faceted 90 degree bend, double-layer 1.5" baffle, side-mounted terminal cup
  • Cabinet: 31" W x 15.00" D x 7.75" H measured in down fire position, 9.50" tall installed on its feet, square corners, ships dry

Technical specifications

SeriesProline X Performance Optimized Down Fire
Driver-Specific FitmentRockford Fosgate R2SD4-10 D4 (Dual 4 Ohm)
Enclosure TypePorted | Down Fire Geometry | Floor-Coupled
Baffle ConfigurationDown Firing - Driver Fires Toward Floor
External Width31 Inches
External Depth15.00 Inches
External Height7.75 Inches (Cabinet Only)
FeetIncluded - 1.75 Inch Standoff, Required For Down Fire Operation
Installed Height9.50 Inches (7.75 Cabinet Plus 1.75 Feet) - MEASURE AGAINST THIS, NOT THE CABINET HEIGHT
Dimension ReferenceAll External Dimensions Measured In Down Fire Position
Internal Volume (Gross)1.39 Cubic Feet
Internal Volume (Net After Displacement)1.26 Cubic Feet
Port TypeL-Wrap Slot | One Folded Wall | Single Faceted 90 Degree Bend
Port Tuning (Fb)35.5 Hz
Port Channel3.25 x 6.25 Inches (20.3 Square Inches)
Port Path Length27.05 Inches (Centreline)
Port Mouth Area17.7 Square Inches (2.00 Inch Corner Chamfer)
Port Air Velocity13.6 m/s At Tuning (17.0 m/s Chuff Threshold)
Predicted F331.7 Hz (Anechoic)
Passband Ripple2.49 dB (Anechoic)
Subsonic Filter28 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs39.30 Hz
Driver Qts0.730
Driver Qes / Qms0.810 / 7.000
Driver Vas21.700 Liters / 0.766 Cubic Feet
Driver Sd333.0 Square Centimeters
Driver Re6.6 Ohm
Driver Xmax8mm (One-Way)
Driver Displacement0.04 Cubic Feet (Published by Rockford Fosgate)
Driver Sensitivity82.5 dB
Driver Power Handling200 Watts RMS
Driver Overall Diameter10.840 Inches (Rockford Fosgate Spec)
Mounting Depth Required3.417 Inches (Rockford Fosgate Spec)
Cutout Diameter9.125 Inches (Rockford Fosgate Spec)
Woofer Ring11.750 Inch OD, Bonded Under The Baffle In A Machined Recess
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Windowed Brace Between Cutout And Port Terminus
JoineryV-Groove and Dado (CNC-Cut)
Front Baffle ConstructionDouble-Layer 1.5" MDF | Outer Layer Flush Recess, Driver Mounts To Inner Layer
Corner ProfileSquare (Down Fire Series Standard)
Mounting Hardware8 x #8-32 Hurricane Nuts Fitted (16 Positions Cut For Driver Orientation) | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual 4 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Side Mounted | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power140-200 Watts RMS (Rockford Fosgate Rated: 200W RMS)
Carpet FinishPlush Black
Bundle OptionsEnclosure Only (Bring Your Own Rockford Fosgate R2SD4-10)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

Net airspace
1.26
cu ft
Tuning
35.5
Hz · Fb
Half power
31.7
Hz · F3, anechoic
Xmax at
286
W RMS · 28 Hz subsonic
With NO filter
68
W RMS · unfiltered
Port
13.6
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 = 48.5
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 EBP 48.5
Rockford Fosgate R2SD4-10 · EBP 48.5
Under 50 the raw number leans sealed. The Rockford Fosgate R2SD4-10 reads 48.5, 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

1.26 cu ft net against a 21.7 L Vas, vented at 35.5 Hz.

Fb = 35.5 Hz  ·  F3 = 31.7 Hz  ·  passband ripple 2.49 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 35.5
Rockford Fosgate R2SD4-10 · Fb 35.5 Hz, F3 31.7 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.

03Perceived Ported vs Sealed

This cabinet, 1.26 cu ft net vented at 35.5 Hz, against Rockford Fosgate's recommended sealed box, 0.70 cu ft.

Ported Fb 35.5 Hz  ·  the 0.70 cu ft sealed box runs Qtc 1.06, Fc 57 Hz
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +7.0 dB at 31 Hz
Ported · this cabinet, 1.26 cu ft, Fb 35.5 HzRockford Fosgate's recommended sealed, 0.70 cu ft net, Qtc 1.06
Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is Rockford Fosgate's recommended sealed box, 0.70 cu ft, not this cabinet with the port blocked: two different boxes, because that is the choice a buyer actually has. Across 25 to 60 Hz the vent is worth 7.0 dB at its widest and 5.5 dB on average. This is the anechoic picture, which is not what you hear in a car.

04Real World Ported vs Sealed

The same two boxes with cabin gain applied, 45 Hz corner, 18 dB ceiling.

Flatness across 25–60 Hz: ported 2.3 dB spread, the 0.70 cu ft sealed box 4.1 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +7.0 dB at 31 Hz
Ported, in-car · 2.3 dB spreadRockford Fosgate's recommended sealed, 0.70 cu ft net, in-car · 4.1 dB spread
Cabin gain lifts both boxes by the same amount, so the gap between them does not change: what changes is the shape each one ends up with. A car pressurises below roughly 45 Hz, which fills in the sealed box's shallower rolloff and over-drives it where the ported box is already flat. Across 25 to 60 Hz, the band kick and bass fundamentals occupy, this alignment holds 2.3 dB of spread against 4.1 dB for Rockford Fosgate's recommended sealed box, 0.70 cu ft. Flatter is the whole point of tuning this high. The two alignments converge at the bottom of the band rather than crossing cleanly, so there is no meaningful subsonic advantage either way here. Cabin gain here is a house assumption, not a measurement of your vehicle.

05The 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 Rockford Fosgate's published 8.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 286 W with a 28 Hz subsonic  ·  68 W with none  →  the filter is worth 4.2×
20 30 50 70 100 150 200 0 4 8 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 8.0 mm 286 W reaches Xmax here
286 W · subsonic at 28 Hz, 24 dB/oct68 W · no subsonic filterXmax 8.0 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 8.0 mm. With a 28 Hz subsonic that takes 286 W, reached first at 26 Hz. Take the filter away and the same cabinet reaches 8.0 mm on 68 W — the filter is worth 4.2× 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 68 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 — Rockford Fosgate rate this one at 200 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 200 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 shallowest Rockford ten I build for is also the flattest in the car. 2.3 dB against the P2's 2.36, the P1's 2.49, and a long way clear of the P3 at 4.76 and the T1 at 4.78.

That is the damping doing it. A 0.73 Qts with 21.7 litres of compliance is a motor that does not want to ring, and a vented box built around a driver like that sits flat without being forced. The port ends up at 31 percent of its turbulence limit and 13.6 metres per second at the mouth.

The trade is power. 200 watts, 8.0 mm of travel. That is where the depth came from. If your install has room for 6.38 inches, the T1 ten is 600 watts and 16 mm and it is a genuinely different product, but its in-car curve is 4.78 dB and you should look at both numbers before deciding which one you actually want.

Dual 4 ohm: 2 ohms parallel or 8 ohms series. Subsonic at 28 Hz. Ships dry.

Questions

Why is this enclosure tuned to 35.5 Hz?

A 39.3 Hz resonance with 21.7 litres of Vas and a 0.73 Qts is a compliant, heavily damped motor, and heavy damping is what keeps a vented alignment from peaking. 1.26 cubic feet at 35.5 Hz produces an F3 of 31.7 Hz with the port at 31 percent of its turbulence limit. Tuning is chosen for in-car response rather than for an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz, so a box tuned very low reinforces a region the cabin is already reinforcing and leaves 40 to 60 Hz thin. In this cabinet that lands at 2.3 dB of in-car spread across 25 to 60 Hz, which is where kick and bass fundamentals live.

Does this enclosure ship with polyfill?

No, and on this build in particular do not add any. Every sealed Proline X enclosure ships with polyfill pre-installed; a ported one must not, because damping material changes the effective volume the port is tuned against. The port on this cabinet is cut to 27.05 inches of centreline path for 35.5 Hz. Stuff it and you move the tuning without shortening the port, which gives you a mistuned box rather than a bigger-sounding one. The 2.49 dB passband you are paying for depends on it staying dry.

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 Rockford Fosgate R2SD4-10 at 83 percent of its usable travel at full rated power; without it there is no meaningful number to quote, because the excursion curve does not converge. On a sealed build a subsonic filter is an improvement. Here it is required equipment.

How much power can I run?

Rockford Fosgate rate the R2SD4-10 at 200 W RMS and that is the thermal ceiling. The figures on the Performance Graphs tab are a different quantity: they are mechanical limits, the power at which the cone reaches the end of its linear travel in this specific cabinet. Here the cone sits at 83 percent of usable travel at the driver's own rating, so heat is what stops you, not travel. Final wired impedance and amplifier output are separate questions again.

Would a sealed box be better for me?

The two alignments converge at the bottom of the band on this driver rather than crossing cleanly, so there is no meaningful subsonic advantage either way. Above 25 Hz the vent is the louder of the two for the same power. The Performance Graphs tab plots this cabinet, 1.26 cubic feet vented at 35.5 Hz, against Rockford Fosgate's recommended sealed box, 0.70 cu ft, so you can judge it yourself.

What is the L-wrap port and why does it matter?

It is a slot port formed by one folded wall: a leg down the long side of the cabinet past the woofer ring, one faceted 90 degree bend, and a leg across the end opening through a chamfered corner. On this cabinet that is 27.05 inches of centreline path and 20.3 square inches of channel, exiting a 17.7 square inch mouth. Air leaves at 13.6 metres per second at tuning against a 17.0 threshold, and the channel runs at 31 percent of its turbulence limit. One wall and one bend rather than a serpentine's three means less wall area inside the box, fewer joints to leak, and one place for flow to separate instead of three.

How is this enclosure built?

V-groove and dado joinery in 0.75 inch Langboard Elite MDF with a double-layer 1.5 inch baffle. The driver mounts to a 11.750 inch ring bonded under the baffle in a machined recess, carrying eight #8-32 hurricane nuts so it threads into steel rather than MDF. A windowed brace sits 3.42 inches clear of the cutout edge and 2.11 inches clear of the port terminus; the window is not weight saving, a solid panel there would split the cavity and make the box a bandpass. Walls seat into dados in both the lid and the baffle. Square corners, plush black carpet, side-mounted terminal cup.

Is the R2SD4-10 included?

No. This is an enclosure only, cut and folded for the Rockford Fosgate R2SD4-10 specifically. The 9.125 inch cutout, the 3.417 inch mounting depth allowance and the 1.26 cubic foot alignment all come from Rockford Fosgate's published parameters for this exact driver, and the port is sized against its Xmax and power rating. It is not a universal box with a 10 inch hole in it. Bring your own driver.

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