Soundqubed HDX4.2 Series 18" Subwoofer 4" DVC 4,000 Watts RMS D2/D4
Soundqubed HDX4.2 Series 18" Subwoofer 4" DVC 4,000 Watts RMS D2/D4 - Dual 2 Ohm is backordered and will ship as soon as it is back in stock.
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Soundqubed HDX4.2 Series 18" Subwoofer 4" DVC 4,000 Watts...
Description
Description
SoundQubed HDX4.2-18 — 4,000W RMS Competition-Grade 18" Subwoofer
The SoundQubed HDX4.2 Series 18" subwoofer is the largest and most powerful driver in the HDX4.2 lineup — a full-size, competition-ready 18-inch subwoofer built for builders who want maximum cone area, infrasonic bass extension, and the kind of low-end output that physically moves air and people. Rated at 4,000 watts RMS and 8,000 watts peak, the HDX4.2-18 is powered by a 402 oz magnet, a 4-inch diameter voice coil with a 70mm coil length, and a motor assembly engineered for extreme linear excursion across a massive 1,200 cm² cone area. Available in Dual 2 Ohm (D2) and Dual 4 Ohm (D4) configurations, this sub is built for wall builds, trunk builds, and any application where maximum displacement and infrasonic output are the goal.
With an Xmax of 23mm (±) and Xmech of 47mm (±), the HDX4.2-18 delivers controlled linear excursion across its enormous cone area, producing authoritative sub-bass extension down to a free-air resonance (Fs) of 31.6 Hz (D2) / 31.7 Hz (D4). With sensitivity ratings of 90.3–90.4 dB, this is the most efficient driver in the HDX4.2 lineup — capable of producing serious SPL output even on moderate amplifier power, and absolutely devastating when fed its full 4,000W RMS rating.
Why Choose the SoundQubed HDX4.2-18?
- 4,000W RMS / 8,000W Peak Power: Handles extreme amplifier output without flinching — built for high-power mono block amplifiers in daily and competition installs.
- 402 oz Magnet Assembly: Massive motor force delivers exceptional BL (17.8 N/A D2 / 23.3 N/A D4) for precise, controlled cone movement at high excursion levels.
- 4" Voice Coil, 70mm Coil Length: Extended coil length maximizes gap interaction for superior thermal management and sustained high-power performance.
- 1,200 cm² Cone Area (SD): The largest cone in the HDX4.2 lineup — maximum air displacement for the deepest, most physical sub-bass output.
- 23mm Xmax / 47mm Xmech: Exceptional linear and mechanical excursion — deep, authoritative bass without bottoming out.
- Dual 2 Ohm & Dual 4 Ohm Available: Wire D2 to 1Ω or 4Ω, wire D4 to 2Ω or 8Ω — maximum flexibility for any amplifier's stable impedance load.
- Ported Enclosure Optimized: Recommended ported volume 5–7 ft³ and sealed 3.0–5.75 ft³ — built to breathe and move in a large, properly tuned vented box.
- 90.3–90.4 dB Sensitivity: The most efficient driver in the HDX4.2 lineup — gets devastatingly loud without demanding every last watt from your amplifier.
Amplifier & Enclosure Recommendations
The HDX4.2-18 is designed to be paired with a high-output mono block amplifier capable of delivering 4,000W RMS or more at the wired impedance load. For the D2 (Dual 2 Ohm) variant, wire the coils in parallel for a 1Ω final load or in series for 4Ω. For the D4 (Dual 4 Ohm) variant, wire in parallel for 2Ω or in series for 8Ω. Most high-power Class D mono amps are stable at 1Ω, making the D2 the most common choice for single-sub builds.
For enclosures, a ported box tuned to 28–34 Hz in the 5–7 ft³ range will maximize SPL output and infrasonic bass extension. The HDX4.2-18 is optimized for ported loading — its large cone area and long-throw suspension need room to breathe. A sealed enclosure in the 3.0–5.75 ft³ range can work for tighter, more controlled bass in applications where ported isn't practical.
Electro Acoustic Specifications & Thiele Small Parameters
| Specification | HDX4.2-18D2 | HDX4.2-18D4 |
|---|---|---|
| Woofer Size | 18" | 18" |
| RMS Power | 4,000 W | 4,000 W |
| Peak Power | 8,000 W | 8,000 W |
| Magnet Weight | 402 oz | 402 oz |
| Coil Diameter | 4 in | 4 in |
| Coil Length | 70 mm | 70 mm |
| Fs | 31.6 Hz | 31.7 Hz |
| Impedance | 2+2 Ohm | 4+4 Ohm |
| QMS | 3.56 | 3.30 |
| QES | 0.52 | 0.55 |
| QTS | 0.45 | 0.47 |
| VAS | 114.0 L | 113.2 L |
| Le | 0.99 mH | 1.65 mH |
| η (No) | 0.67% | 0.63% |
| CMS | 0.06 mm/N | 0.06 mm/N |
| Sensitivity (1W/1M) | 90.3 dB | 90.4 dB |
| BL | 17.8 N/A | 23.3 N/A |
| Xmax (±) | 23 mm | 23 mm |
| Xmech (±) | 47 mm | 47 mm |
| SD | 1,200 cm² | 1,200 cm² |
Mounting Dimensions
| Model | A | B | C | D |
|---|---|---|---|---|
| HDX4.2-18D2 | 465 mm / 18.3" | 425 mm / 16.73" | 260 mm / 10.24" | 288 mm / 11.34" |
| HDX4.2-18D4 | 465 mm / 18.3" | 425 mm / 16.73" | 260 mm / 10.24" | 288 mm / 11.34" |
Enclosure Suggestions
| Enclosure Type | HDX4.2-18 D2/D4 |
|---|---|
| Sealed Enclosure | 3.0–5.75 ft³ |
| Ported Enclosure | 5–7 ft³ |
Frequently Asked Questions
What amplifier do I need for the SoundQubed HDX4.2-18?
You need a mono block amplifier rated at 4,000W RMS or more at your wired impedance. The D2 wired to 1Ω is the most common pairing. Look for a high-current Class D mono amp stable at 1Ω for best results.
Should I choose the D2 or D4 version?
Choose D2 (Dual 2 Ohm) if your amplifier is stable at 1Ω (parallel) or 4Ω (series) — this is the most common configuration. Choose D4 (Dual 4 Ohm) if your amp is stable at 2Ω (parallel) or you need an 8Ω final load (series).
What size box does the HDX4.2-18 need?
For ported, use 5–7 ft³ tuned to approximately 28–34 Hz for maximum SPL and infrasonic bass extension. For sealed, use 3.0–5.75 ft³ for tighter, more controlled bass.
Can this subwoofer handle daily use or is it competition-only?
The HDX4.2-18 is built for both. Its 90.3–90.4 dB sensitivity — the highest in the HDX4.2 lineup — means it gets devastatingly loud even on moderate power, while its 4,000W RMS rating and 402 oz motor make it a serious competition contender.
