Diamond HEX S124

12″ subwoofer · 4 Ω · 250 W RMS

27 HzFs, resonance

0.29Qts

2.59 ft³Vas

0.35″Xmax

250 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

The published specs don’t add up:

Re 5.1 Ω doesn't look like a 4 Ω coil — check the spec sheet.

Recommended box

For a sedan, one sub, 250 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

0.64 ft³ (18 L)

Net volume

Bass character (Qtc)	Flat and accurate · 0.66
Fc	61 Hz
F3 (−3 dB, no cabin gain)	70 Hz
Example box (outside)	14 3/16″ × 14 3/16″ × 9 5/16″

Open sealed box in designer

Ported

deeper, louder

2.08 ft³ (59 L)

Net volume

Tuning (Fb)	30 Hz
Port	slot 1 9/16 × 14 5/16″, 28 1/4″ long
Port velocity at 250 W	51 ft/s
F3 (−3 dB, no cabin gain)	31 Hz
Example box (outside)	31 1/2″ × 15 3/4″ × 12 1/4″

Open ported box in designer

Deeper: 1.34 ft³ (38 L) tuned to 35 Hz, 31 1/2″ × 15 3/4″ × 9 5/8″ 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	12″
Voice coils	4 Ω
RMS power	250 W
Fs	27 Hz
Qts	0.29
Qes	0.319
Qms	3.59
Vas	2.59 ft³

Re	5.1 Ω
Sd	70.1 in²
Xmax	0.35″
Vd	24.3 in³ calc.
Mms	137 g calc.
BL	19.3 T·m calc.
EBP	85 — sealed or ported calc.
Sensitivity, 1 W / 1 m	88.6 dB calc.

Mounting dimensions

Cutout diameter	11 3/16″
Mounting depth	3 1/4″
Overall diameter	12 3/8″

“≈” 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

web.archive.org/web/20081203011508/http://www.diamondaudio.com:80/PDF/current/HE

Other Diamond 12″ models

Diamond CM312D2 12″ · dual 2 Ω
Diamond CM312D4 12″ · dual 4 Ω
Diamond D122 12″ · dual 2 Ω
Diamond D124 12″ · dual 4 Ω
Diamond D312D2 12″ · dual 2 Ω
Diamond D312D4 12″ · dual 4 Ω
Diamond D612D2 12″ · dual 2 Ω
Diamond D612D4 12″ · dual 4 Ω
Diamond D912D2 12″ · dual 2 Ω
Diamond D912D4 12″ · dual 4 Ω
Diamond DE122 12″ · dual 2 Ω
Diamond DE124 12″ · dual 4 Ω

Similar 12″ subwoofers from other brands

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

ESX SXE12D2 (2x2 Ohm) 0.74 ft³ sealed · 2.37 ft³ ported
Ground Zero GZRW 300X (4 Ohm) 0.71 ft³ sealed · 2.26 ft³ ported
ESX SX1240 (4 Ohm) 0.71 ft³ sealed · 2.33 ft³ ported
Elemental Designs e12kd4 0.74 ft³ sealed · 2.26 ft³ ported
Alpine SWE-1243E (Type-E) 0.78 ft³ sealed · 2.65 ft³ ported
Alpine SWG-1244 (Type-G) 0.78 ft³ sealed · 2.30 ft³ ported

FAQ

What box does the Diamond HEX S124 need?

Recommended net volume: 0.64 ft³ sealed, 2.08 ft³ ported tuned to 30 Hz — for one sub in a sedan at 250 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Diamond HEX S124 Thiele/Small specs?

Fs 27 Hz, Qts 0.29, Vas 2.59 ft³, Xmax 0.35″, Sd 70.1 in².

What is the Diamond HEX S124 mounting depth?

Mounting depth is 3 1/4″, cutout diameter 11 3/16″. The inside depth of the box must exceed the mounting depth by at least 1″.

How much power does the Diamond HEX S124 handle and how do I wire it?

RMS power rating: 250 W. Wiring for several subs and amp power — in the wiring calculator.