Ascendant Audio SMD V2 18 D2

18″ subwoofer · dual 2 Ω · 5,000 W RMS

34.2 HzFs, resonance

0.31Qts

2.17 ft³Vas

1.38″Xmax

5,000 WRMS

Source	web.archive.org · manufacturer data
Checked against source	October 2026
Thiele/Small parameters	complete
Mounting dimensions	3 of 4 — missing: magnet diameter; the designer will use an estimate

Recommended box

For a sedan, one sub, 5,000 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

smaller, tighter

2.95 ft³ (83.5 L)

Net volume

Bass character (Qtc)	Dry and tight · 0.41
Fc	45 Hz
F3 (−3 dB, no cabin gain)	92 Hz
Example box (outside)	20 1/16″ × 20 1/16″ × 17 7/16″

Open sealed box in designer

Ported

deeper, louder

5.54 ft³ (157 L)

Net volume

Tuning (Fb)	34 Hz
Port	slot 5 7/8 × 19 7/16″, 39 1/16″ long
Port velocity at 5,000 W	89 ft/s
F3 (−3 dB, no cabin gain)	31 Hz
Example box (outside)	31 1/2″ × 20 7/8″ × 26 7/8″

At 5,000 W this example’s port will be noisy: air speed 89 ft/s, while the limit is 82 ft/s. It stays quiet up to about 4,200 W. Full power needs a port of at least 125.2 in², which means a bigger box than this example — size it in the designer.

Open ported box in designer

Deeper: 3.60 ft³ (102 L) tuned to 30 Hz, 31 1/2″ × 20 7/8″ × 22″ outside — a bigger box with flatter deep bass. Open in the calculator

Where to buy Amazon

Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Size	18″
Voice coils	dual 2 Ω
RMS power	5,000 W
Fs	34.2 Hz
Qts	0.31
Qes	0.33
Qms	6.82
Vas	2.17 ft³

Re (one coil)	1.4 Ω
Sd	187.6 in²
Xmax	1.38″
Vd	258.4 in³ calc.
Mms	732 g calc.
BL	25.8 T·m calc.
EBP	104 — suits ported calc.
Sensitivity, 1 W / 1 m	90.7 dB calc.

Mounting dimensions

Cutout diameter	16 3/4″
Mounting depth	15″
Overall diameter	18 1/2″

“≈” 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 Ascendant Audio 18″ models

Ascendant Audio Havoc 18 D1 18″ · dual 1 Ω
Ascendant Audio Havoc 18 D2 18″ · dual 2 Ω
Ascendant Audio Mayhem 18 D1 18″ · dual 1 Ω
Ascendant Audio Mayhem 18 D2 18″ · dual 2 Ω
Ascendant Audio SMD Signature 18 D1 18″ · dual 1 Ω
Ascendant Audio SMD Signature 18 D2 18″ · dual 2 Ω
Ascendant Audio SMD V2 18 D1 18″ · dual 1 Ω
Ascendant Audio TEAM 18 D1 18″ · dual 1 Ω
Ascendant Audio TEAM 18 D2 18″ · dual 2 Ω

Similar 18″ subwoofers from other brands

Close in Fs, Qts and Vas — a box of similar volume will suit them.

DC Audio NEO 4.0 18 D0.7 2.54 ft³ sealed · 5.33 ft³ ported
DC Audio NEO 4.0 18 D1 2.54 ft³ sealed · 5.33 ft³ ported
DC Audio NEO 4.0 18 D2 2.54 ft³ sealed · 5.33 ft³ ported
Ground Zero GZHW 18XSPL-D1 (2x1 Ohm) 1.94 ft³ sealed · 5.33 ft³ ported
Sundown Audio SDDN-18 D1 2.84 ft³ sealed · 5.23 ft³ ported
Fi Audio OMEGA 18 D1 2.49 ft³ sealed · 5.54 ft³ ported

FAQ

What box does the Ascendant Audio SMD V2 18 D2 need?

Recommended net volume: 2.95 ft³ sealed, 5.54 ft³ ported tuned to 34 Hz — for one sub in a sedan at 5,000 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Ascendant Audio SMD V2 18 D2 Thiele/Small specs?

Fs 34.2 Hz, Qts 0.31, Vas 2.17 ft³, Xmax 1.38″, Sd 187.6 in².

What is the Ascendant Audio SMD V2 18 D2 mounting depth?

Mounting depth is 15″, cutout diameter 16 3/4″. The inside depth of the box must exceed the mounting depth by at least 1″.

How much power does the Ascendant Audio SMD V2 18 D2 handle and how do I wire it?

RMS power rating: 5,000 W. Dual 2 Ω voice coils: series gives 4 Ω, parallel gives 1 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.