Description
The RCF SUB 8004-AS (SUB8004-AS, SUB 8004AS) is an active 18-inch subwoofer with a 4-inch inside/outside voice coil woofer and a built-in 2500 W peak (1250 W RMS) digital amplifier. It reaches 136 dB max SPL and plays from 30 Hz to 120 Hz. The rear panel has a 90/120 Hz crossover with a filtered output for your tops, a Deep/Punch switch, a time delay control, a phase switch and a cardioid mode, all in a Baltic birch plywood cabinet that weighs 123.5 lb (56 kg).
RCF builds it for live sound, rental and touring use. The HDL 10-A and HDL 20-A line array modules can stack on top of it.
SUB 8004-AS, Open Box or with a cover: which should I buy?
| Option | What you get | Best for |
|---|---|---|
| SUB 8004-AS (this page) | One new subwoofer | Most buyers |
| Open Box SUB 8004-AS | The same subwoofer sold as open box | Adding a sub to an existing rig |
| RCF COVER-SUB8004 | RCF's padded cover made for this subwoofer, sold separately | Protecting it in transport |
| ProX X-RCF-SUB8004AS flight case | A ProX road case with wheels, sold separately | Touring and rental |
How is the SUB 8004-AS different from the SUB 8006-AS and SUB 708-AS MK3?
The SUB 8006-AS is the double 18-inch version with twice the amplifier power. The SUB 708-AS MK3 is a lighter, lower-power 18-inch sub.
| SUB 8004-AS | SUB 8006-AS | SUB 708-AS MK3 | |
|---|---|---|---|
| Woofer | 1 x 18-inch, 4-inch voice coil | 2 x 18-inch, 4-inch voice coil | 1 x 18-inch, 3-inch voice coil |
| Amplifier | 2500 W peak (1250 W RMS) | 5000 W peak (2500 W RMS) | 1400 W peak (700 W RMS) |
| Max SPL | 136 dB | 141 dB | 133 dB |
| Frequency response | 30 Hz to 120 Hz | 30 Hz to 120 Hz | 35 Hz to 120 Hz |
| Weight | 123.5 lb (56 kg) | 212.5 lb (96.4 kg) | 89.5 lb (40.6 kg) |
Pick the SUB 8004-AS for touring-grade output from a single 18-inch cabinet. Pick the SUB 8006-AS when you need the most low end per cabinet, or the SUB 708-AS MK3 when weight matters more than output.
How does the cardioid mode work?
It works in groups of three subwoofers. Point two forward with the cardioid switch released and one backward with the switch pressed, and give all three the same delay, sensitivity and crossover settings. A cardioid group sends less low end backward, toward the stage.
What do the Deep/Punch and crossover switches do?
Deep gives a flat response down to 30 Hz; Punch adds a boost at 70 Hz. The crossover switch sets a 24 dB per octave low-pass at 90 Hz or 120 Hz, and the XOVER output sends the matching high-passed signal to your top speakers, so you can run tops without an external crossover.
Can I time-align it with my tops?
Yes. A time delay encoder on the rear panel sets the delay, marked in meters of distance. When you use several subwoofers in one group, RCF says to set them all to exactly the same delay.
Can I stack line array modules on it?
Yes. RCF approves the HDL 20-A on top in the horizontal position and the HDL 10-A horizontal or vertical, using the module's fly bar and RCF's locking accessory. The NXL 24-A column also stacks on it. The top of the cabinet has an M20 pole mount thread.
Does it have wheels?
No, but the rear panel has mounting points for four wheels, and RCF sells swivel and fixed wheel kits separately. It has one handle on each side.
SUB 8004-AS specifications
| Type | Active subwoofer, vented |
| Woofer | 18-inch, 4-inch inside/outside voice coil |
| Amplifier | Digital, 2500 W peak (1250 W RMS) |
| Frequency response | 30 Hz to 120 Hz |
| Max SPL | 136 dB at 1 m |
| Crossover | Low-pass 90 or 120 Hz, 24 dB per octave; high-passed XOVER output |
| Controls | Input sensitivity, Deep/Punch, crossover, time delay, phase, cardioid |
| Input sensitivity | -2 dBu / +4 dBu |
| Inputs and outputs | XLR in, XLR link out, XLR crossover out |
| Power | powerCON in, AC power link out |
| Protections | Thermal, RMS, fast limiter |
| Cooling | Convection (no fan) |
| Cabinet | Baltic birch plywood, textured black finish, steel grille |
| Handles | One each side |
| Pole mount | M20 thread |
| Dimensions (H x W x D) | 27.56 x 21.97 x 27.56 in (700 x 558 x 700 mm) |
| Weight | 123.5 lb (56 kg) |
| Shipping weight | 132.3 lb (60 kg) |
Specifications from the RCF SUB 8004-AS product page, spec sheet and user manual.
What else fits the SUB 8004-AS?
RCF's COVER-SUB8004 padded cover and the ProX flight case. Compare every RCF sub in RCF SUB series powered subwoofers, see every brand in 18-inch subwoofers, or browse everything from RCF.
Financing Options
Hassle-Free Financing Available
Get the gear you need now and pay over time. Perfect for working DJs, artists, and sound pros who need pro-grade speakers, lighting, and cases to stay competitive.
- Shop Pay & Afterpay for instant financing right at checkout
- Acima, Synchrony, Progressive & Snap lease-to-own and financing options
- Fast approvals so you buy today and pay monthly
Military & First Responder Discounts
We're proud to support those who serve. Active-duty military, veterans, and first responders qualify for a special discount on your gear. See our Military Discount details here and how to redeem.