Sundown Audio SA Classic 6.5 D2

6.5″ subwoofer · dual 2 Ω · 300 W RMS

Fs 48.9 HzQts 0.45Vas 0.14 ft³Xmax 0.39″

Recommended box

For a sedan, one sub, 300 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 volume0.21 ft³ (6 L)
Qtc0.59
Fc63 Hz
F3 (−3 dB, no cabin gain)81 Hz
Example box (outside)9 1/16″ × 9 1/16″ × 8 3/16″
Open sealed box in designer

Ported

Net volume0.42 ft³ (12 L)
Tuning (Fb)36 Hz
Portslot 1 15/16 × 14 5/16″, 132 15/16″ long
Port velocity at 300 W24 ft/s
F3 (−3 dB, no cabin gain)33 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 12 7/8″

The volume and tuning are the recommendation, but the port doesn’t fit this example box. Size the box and port in the designer.

Open ported box in designer
2030405060801001502006066727884HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs48.9 Hz
Qts0.45
Qes0.5
Qms4.82
Vas0.14 ft³
Re (one coil)2 Ω
Sd22.2 in²
Xmax0.39″
Vd8.7 in³ calc.
Mms75 g calc.
BL9.6 T·m calc.
EBP98 — sealed or ported calc.
Sensitivity, 1 W / 1 m81.8 dB calc.

General

Size6.5″
Voice coilsdual 2 Ω
RMS power300 W

Mounting dimensions

Ø7 1/8″cutout Ø5 7/8″mounting depth 3 3/4″magnet Ø5 1/2″
Cutout diameter5 7/8″
Mounting depth3 3/4″
Overall diameter7 1/8″
Magnet diameter5 1/2″

The spec sheet's Sd of 33.5 in² is the area of a 6.5″ circle, not the cone's radiating area — not used.

Cone area (Sd) calculated from Fs, Vas and Mms: 22.2 in².

“≈” 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 Sundown Audio 6.5″ models