URAL Ultimatum 15 (1+1)

15″ subwoofer · dual 1 Ω · 4,000 W RMS

Fs 28.3 HzQts 0.36Vas 1.35 ft³Xmax 1.57″
The published specs don’t add up:

Recommended box

For a sedan, one sub, 4,000 W. It’s the same math as the designer’s step-by-step mode, where you can fit the box to your space, vehicle and amp and get plans, a cut sheet and DXF.

Sealed

Net volume1.71 ft³ (48.5 L)
Qtc0.48
Fc38 Hz
F3 (−3 dB, no cabin gain)63 Hz
Example box (outside)17 5/16″ × 17 5/16″ × 14 5/16″
Open sealed box in designer

Ported

Net volume2.37 ft³ (67 L)
Tuning (Fb)25 Hz
Portround port Ø3″, 10 1/2″ long
Port velocity at 4,000 W668 ft/s
F3 (−3 dB, no cabin gain)24 Hz
Example box (outside)22 5/16″ × 18 1/8″ × 14 3/8″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs28.3 Hz
Qts0.36
Qes0.41
Qms3.1
Vas1.35 ft³
Re (one coil)≈ 0.85 Ω
Sd≈ 124 in²
Xmax1.57″
EBP69 — sealed or ported calc.
Sensitivity, 1 W / 1 m85.3 dB calc.

General

Size15″
Voice coilsdual 1 Ω
RMS power4,000 W

Mounting dimensions

Ø15 9/16″cutout Ø14 1/8″mounting depth 11 13/16″magnet Ø9 13/16″
Cutout diameter14 1/8″
Mounting depth11 13/16″
Overall diameter15 9/16″
Magnet diameter9 13/16″

“≈” means the value isn’t in the spec sheet and a typical value for the size is used; “calc.” means it’s calculated from the published parameters. Check the manufacturer’s spec sheet before you build.

Data sources

Other URAL 15″ models