PowerBass XL-1240T — 12″ Shallow Sub, 400W RMS

The most common compromise in car audio is choosing between a proper 12″ subwoofer and the space behind your rear seats. The PowerBass XL-1240T removes that compromise entirely. At Safe and Sound, it’s the shallow mount subwoofer we recommend when a customer wants genuine 12″ performance — 400W RMS, a 33Hz resonant frequency, and a 140 oz motor — but simply hasn’t got the depth for a conventional driver. With a mounting depth of just 3.8″, it fits where full-size subs can’t, and it doesn’t apologise for it.

Why choose the PowerBass XL-1240T?

Step up from a 10″ shallow subwoofer and you gain meaningfully more cone area, a larger magnet, and lower, more authoritative bass extension. The XL-1240T steps up from its 10″ sibling in exactly these ways — yet the mounting depth rises by just 0.4″ (from 3.4″ to 3.8″). That’s a significant improvement in output and low-frequency reach for a very modest increase in space requirements.

• More cone, more bass — the 12″ flat injection-moulded cone moves more air than any 10″ driver, delivering fuller, deeper low-end that you feel as much as hear.
• Larger motor, better control — the 140 oz inverted ferrite magnet (up from 116 oz on the 10″ models) provides greater control authority over the cone, keeping bass tight and articulate even at higher output levels.
• Reaches low — a resonant frequency of 33Hz means the XL-1240T reproduces kick drums, bass guitars, and film soundtracks with proper weight and extension, not just mid-bass warmth.
• Handles power cleanly — 400W RMS and a vented 2″ KSV voice coil former mean the driver copes with serious amplifier output without compressing or distorting.
• Quiet basket, clean sound — the proprietary composite Poly/Glass Fibre basket is engineered to be non-resonant, so only the music comes through.

Shallow mount — step up to 12″

The XL-1240T is optimally designed for a small sealed enclosure. In a well-built sealed box, the driver’s Qts of 0.526 and Vas of 42.4 litres translate to a tight, musical bass character — punchy and fast rather than slow and boomy. If you’re building a custom enclosure to fit under a load floor, behind rear seats, or into a van conversion, this driver rewards careful box tuning with excellent results.

Not sure where to start with an enclosure? The Safe and Sound workshop builds custom sealed boxes regularly and can advise on the ideal internal volume for the XL-1240T. Whether you want to bring your vehicle in for a complete professional installation or just need guidance before a DIY build, we’re happy to help.

Key specifications

Specification	Detail
Size	12″ shallow mount subwoofer
Voice coil configuration	Single 4-ohm (SVC)
Power handling	400W RMS / 800W Max
Mounting depth	3.8″ (97mm)
Cutout diameter	11″ (281mm)
Sensitivity	89 dB (1W/1M)
Frequency response	33Hz – 450Hz
Resonant frequency (Fs)	33Hz
Voice coil	2″ vented KSV voice coil former
Xmax	7.5mm
Cone material	Proprietary single-piece injection-moulded flat polypropylene
Basket	Proprietary composite Poly/Glass Fibre, non-resonant
Magnet	Inverted ferrite, 140 oz
Impedance	4-ohm nominal
Terminals	Chrome push terminals
Qts	0.526
Vas	42.4 litres
Recommended enclosure	Small sealed

How does the XL-1240T compare to the 10″ XL-1040T?

If you’re deciding between the two shallow mount subwoofers in the XL family, here’s what the step up to 12″ actually gives you:

Spec	XL-1040T (10″)	XL-1240T (12″)
Power (RMS)	350W	400W
Mounting depth	3.4″	3.8″
Resonant frequency	35Hz	33Hz
Magnet	116 oz	140 oz
Sensitivity	88 dB	89 dB
Cutout diameter	9 5/16″	11″

Need the dual voice coil version for amplifier wiring flexibility? See the XL-1240TD. If you’re unsure which configuration suits your setup, the Safe and Sound team is happy to advise before you order.

What’s in the box

• PowerBass XL-1240T 12″ shallow mount subwoofer (single unit)
• Mounting hardware

Note: an enclosure and amplifier are required and sold separately. The XL-1240T is optimally designed for a small sealed enclosure.