

Performance Optimized · Datasheet
Performance Optimized Down Fire Wide Sealed 12" Enclosure Rockford Fosgate T1 Slim · Single 12" Sealed enclosure
- Net volume
- 1.255 cu ft after displacement and the brace
- Max mounting depth
- 3.03 in
- External dimensions
- 41 in W × 6.9375 in in the down fire position H × 14 in D
- Front baffle
- 1.5 in double baffle, outer layer machined as a flush recess
- Alignment: 1.255 cu ft net. Qtc 1.466, Fc 51.2 Hz, F3 35.9 Hz
- Down Fire Wide: 41"W x 14"D x 6.9375"H in down fire position, excludes the 1.75" standoffs (installed height 8.6875"). Stands lower than the standard 30 x 15 at 8.25"
- Height set by: airspace; 3.16" of clearance above the motor
- Driver: Rockford Fosgate T1S1-12 (1 ohm SVC) or T1S2-12 (2 ohm SVC), 600W RMS, 15mm Xmax, 3.03" mounting depth, 3" voice coil
- Build: Langboard Elite MDF, V-groove and dado, 1.5" double baffle with flush outer recess, windowed U-brace, 12g OFC side-mounted terminal cup
Spec of record
Technical specifications
| Series | Proline X Performance Optimized Down Fire Wide |
|---|---|
| Compatible Driver | Rockford Fosgate T1S1-12 (1 ohm SVC) or T1S2-12 (2 ohm SVC), quantity 1. Direct fit |
| Enclosure Type | Sealed, down fire, floor coupled |
| Intended Fitment | Long, low spaces where height or depth is the limit and 41 in of run is available |
| Firing Direction | Down firing. Feet ship uninstalled, so front or up firing is also possible |
| Chamber Configuration | Single chamber, windowed U-brace, one side-mounted terminal cup |
| External Width | 41 in |
| External Depth | 14 in |
| External Height | 6.9375 in in the down fire position, excludes standoffs |
| Installed Height | 8.6875 in including the 1.75 in standoffs |
| Dimension Reference | All external dimensions measured in down fire position |
| Standard 30 x 15 Version | 8.25 in tall, 1.24 cu ft net |
| Internal Volume, Gross | 1.305 cu ft |
| Internal Volume, Net | 1.255 cu ft after displacement and the brace |
| Height Set By | Airspace; 3.16 in clearance above the motor |
| Alignment | Qtc 1.466, Fc 51.2 Hz, F3 35.9 Hz anechoic |
| Woofer Opening | 11.22 in |
| Mounting Depth Required | 3.03 in |
| Driver Displacement | 0.042 cu ft |
| Driver Free-Air Qts | 1.06 (T1S1-12 parameter set; Rockford states the T1S2-12 shares it). Qtc cannot fall below Qts |
| Voice Coil Configuration | Single Voice Coil, Impedance Set By Driver Model |
| Driver Mounting | 8/32 Threaded Inserts | Stainless Steel Machine Screws Included |
| Recommended Power | 450-600 Watts RMS (Rockford Rated: 600W RMS Continuous) |
| Material | Langboard Elite 3/4 in MDF |
| Joinery | V-groove and dado, CNC cut on ShopSabre routers |
| Front Baffle | 1.5 in double baffle, outer layer machined as a flush recess |
| Internal Bracing | Windowed U-brace, dadoed to the shell |
| Corner Profile | Square (Down Fire series standard) |
| Terminal Cup | One Proline X ABS and carbon fiber composite, side mounted, pre-wired 12 gauge OFC |
| Standoffs | 1.75 in, included, shipped uninstalled |
| Damping | Polyfill installed as a light wall lining |
| Carpet | Plush black |
| Bundle Options | Enclosure only (bring your own T1S1-12 or T1S2-12) |
| Warranty | 1 year limited (enclosure) |
| Built In | Tullahoma, Tennessee, USA |
Modelled response
Performance in this enclosure
01Is it a sealed driver?
Efficiency bandwidth product places the motor before anything else is decided.
02What the box does to it
1.255 cu ft against a 32.4 L Vas.
03The 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 15.0 mm, and in this alignment a subsonic filter barely moves it.
| Param | Value | Unit | Note |
|---|---|---|---|
| Fs | 37.00 | Hz | free-air resonance |
| Qts | 1.060 | T1S1-12 / T1S2-12 | |
| Vas | 32.40 | L | equivalent compliance |
| Sd | 560.0 | cm² | effective piston area |
| Xmax | 15 | mm | one-way linear travel |
| Pe | 600 | W | continuous RMS |
| SPL | 83.3 | dB | 1 W / 1 m, derived from T/S |
Driver parameters as published by loudspeakerdatabase.com, T1S1-12 / T1S2-12. Curves computed against this enclosure’s actual net airspace.
From the shop floor
Installer's take
The T1 Slim 12 is the one to reach for when someone wants 12 inch cone area and has about 3 inches of mounting depth. A full 3 inch four-layer coil and 15mm of one-way Xmax behind an anodized aluminum cone.
Height was solved to the airspace: 6.9375 tall holds 1.255 net, against 1.24 in the standard box, and the motor clears the lid with 3.16 inches to spare. Same air, lower box.
Understand the damping before you buy a box. Qts is 1.06, already above 0.707, so no sealed box of any size makes this driver flat. At 1.255 net it lands at Qtc 1.466 with Fc 51.2 Hz and F3 35.9 Hz: underdamped, with a peak near the corner. That is Rockford's intent.
Wiring is simple because both models are single voice coil. Target 450 to 600 watts RMS.
Measure installed height, not cabinet height: 6.9375 on its own, 8.6875 with the 1.75 inch feet on. The standard 30 by 15 is still the pick if you do not have 41 inches of run.
Before you order
Questions
Why is this cabinet 41 inches wide instead of 30?
Because it trades length for depth and height. The standard Performance Optimized Down Fire platform is 30 wide by 15 deep; this one is 14 deep, 1 inch shallower, and 41 long. Spreading the airspace along 11 more inches lets the cabinet stand 6.9375 inches tall instead of 8.25.
Fourteen inches of depth is the practical minimum, since a 12 inch frame needs about 13 inches of baffle. If your space is long and low rather than deep or tall, this is the shape that fits.
How does this compare to the standard 30 x 15 T1 Slim 12 enclosure?
Same driver, different shape. The standard cabinet is 30 by 15 by 8.25 inches and holds 1.24 cubic feet net. This cabinet is 41 by 14 by 6.9375 inches and holds 1.255 cubic feet net.
The airspace is effectively the same, so the driver behaves the same way in either. Choose the standard box when length is limited; choose this one when height or depth is the limit and you have 41 inches of run.
Why is the Qtc above 1.0? Is this enclosure too small?
No. The high Qtc comes from the driver, not the box. The T1 Slim 12 has a free-air Qts of 1.06, and system Qtc can never fall below the driver's Qts regardless of enclosure size, so no sealed volume reaches a textbook 0.707 alignment with it.
At 1.255 cubic feet net this cabinet lands at Qtc 1.466 with Fc 51.2 Hz and F3 35.9 Hz. A larger box would not make it flat, and a smaller one makes it worse.
How do I wire this enclosure?
Straightforward, because both T1 Slim models are single voice coil. The enclosure has one side-mounted Proline X terminal cup pre-wired in 12 gauge OFC, and the impedance your amplifier sees is the model you install: 1 ohm for the T1S1-12, 2 ohms for the T1S2-12.
Rockford rates both at 600 watts RMS. Target 450 to 600 watts RMS and confirm your amplifier is stable at that load.
Where is the terminal cup located on a down fire enclosure?
Side mounted. Every Proline X Performance Optimized enclosure uses a side mounted terminal cup, whether standard, wedge or down fire, which keeps the connection accessible with the baffle facing the floor. The cup is our Proline X ABS and carbon fiber composite unit, recessed, with stainless hardware, copper ring terminals and pre-wired 12 gauge OFC.
Why are the corners square instead of radiused?
Down Fire cabinets are built with square corners as a series standard. The 3 inch top down corner radius used on other Proline X alignments does not apply here. A down fire box is a low, long platform that sits flat against a floor or cargo deck, and square corners maximize usable internal volume for a given footprint while keeping the cabinet stable on its mounting surface.
How is this enclosure built?
V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF. Every panel joint is a machined interlocking groove that locks the panels before adhesive is applied, which keeps the cabinet airtight under sustained pressure cycling. The front baffle is a 1.5 inch double layer, the outer layer machined as a flush recess around the 11.22 inch cutout.
A windowed U-brace stiffens the long panels, and polyfill is installed as a light wall lining. Do not add more fill; packing a sealed box makes it act larger and moves the alignment off the 1.255 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.
Is the Rockford Fosgate T1 Slim subwoofer included with this enclosure?
No. This listing is for the enclosure only. Bring your own Rockford Fosgate T1S1-12 or T1S2-12. The cutout and mounting depth are direct fit for either model.
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