Prology RX-8 Kraken

8″ subwoofer · 4 Ω · 120 W RMS

Fs 51.6 HzQts 0.56Vas 0.41 ft³

Recommended box

For a sedan, one sub, 120 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 volume0.42 ft³ (12 L)
Qtc0.79
Fc72 Hz
F3 (−3 dB, no cabin gain)68 Hz
Example box (outside)10 1/4″ × 10 1/4″ × 11 5/8″
Open sealed box in designer

Ported

Net volume1.20 ft³ (34 L)
Tuning (Fb)39 Hz
Portslot 1 9/16 × 14 5/16″, 29 1/8″ long
Port velocity at 120 W32 ft/s
F3 (−3 dB, no cabin gain)35 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 8 1/2″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs51.6 Hz
Qts0.56
Qes0.66
Qms3.9
Vas0.41 ft³
Re3.6 Ω
Sd31.9 in²
Xmax≈ 0.39″
Mms49 g calc.
BL9.3 T·m calc.
EBP78 — sealed or ported calc.
Sensitivity, 1 W / 1 m85.9 dB calc.

General

Size8″
Voice coils4 Ω
RMS power120 W

Mounting dimensions

Ø≈ 8 1/4″cutout Ø7 1/16″mounting depth 3 15/16″magnet Ø≈ 4 5/8″
Cutout diameter7 1/16″
Mounting depth3 15/16″

“≈” 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 Prology 8″ models