RCF 4PRO 8003 vs SUB 8003 MK2 vs SUB 8004

RCF Subwoofer Demo

At Datarhyme, we spent an afternoon with RCF at a major distributor’s HQ comparing three of RCF’s most popular mid-range 18-inch active subwoofers: the RCF 4Pro 8003-AS, the RCF SUB 8003-AS II (MK2), and the RCF SUB 8004-AS, with a single RCF TT22-A providing the high frequencies.

Note – this was a listening demo only; no measurement microphones or SPL meters were used. Our impressions are based purely on listening and observation.

Quick Specs & Approx. UK Prices

RCF 4Pro 8003-AS

The 4Pro 8003-AS is the third generation in the 4Pro 8000 line, following the 8001 and 8002. For many years, it was the standard “go-to” RCF 18″ sub. It combines a digital amplifier with some DSP, but its controls are simple and analogue in feel.

Demo impressions

• Output was strong with a respectable amount of bass.
• Extension reached around 40 Hz, but without the lowest-octave “weight” of the newer boxes.
• Limiter light was active on peaks, showing it ran closer to its limits than the others.
• Tight, musical sound, but not as smooth or extended as the MK2 or 8004.

In practice: At nearly 49 kg, it’s heavier than the MK2, and newer models offer deeper, cleaner bass. Today it’s typically a used-market buy around £800–£900, attractive for tight budgets.

RCF SUB 8003-AS II (MK2)

The SUB 8003-AS II (MK2) replaced the 4Pro 8003. It keeps the single 18″ format but brings a more efficient amplifier, deeper tuning, and full digital DSP with presets.

Demo impressions

• Fuller low-end than the 4Pro, extending cleanly to about 35 Hz.
• DSP could push extremely low bass, though that setting reduced headroom.
• Limiter flicker is similar to the 4Pro, but overall more usable output.
• Delay, crossover and cardioid presets added real day-to-day flexibility.

In practice: Around 42 kg and easier to move than the 4Pro, the MK2 balances portability, bass reach and digital control. UK street price is usually £1,200–£1,400.

RCF SUB 8004-AS

Developed to support RCF HDL line arrays, the SUB 8004-AS brings more amplifier headroom, a bigger cabinet and deeper extension.

Demo impressions

• Deepest and cleanest of the three, comfortably reaching ~30 Hz.
• Smooth, powerful bass with clear ease at higher levels.
• “Deep/Punch” switch made little difference in this session.
• Headroom felt abundant — limiter never engaged during our listening.
• Subjectively, the loudest, but also the bulkiest at ~56 kg.

In practice: Heaviest and least portable of the three, and carries a premium of ~£2,200–£2,500. For larger rooms, outdoor events or bass-heavy material, it was the sonic leader.

Overall Results

Verdict: The SUB 8003-AS II (MK2) offered the best value and features, while the SUB 8004-AS sounded the best but was heavier and costlier. The 4Pro 8003-AS was still respectable, but felt dated next to the newer models.

The Latest Model: RCF SUB 8003-AS MK3
Since our demo, RCF have introduced the SUB 8003-AS MK3 as the current model in the line. It keeps the compact single-18″ format but adds:

• 2200 W Class-D amplifier (135 dB max SPL).
• Bass Motion Control (BMC) for tighter low-end at high drive.
• Built-in delay and cardioid presets for quicker arrays.
• Polyurea-coated cabinet for tougher rental life.

Approx. UK price: £1,400–£1,500. If you’re buying today, the MK3 is the logical step; the MK2 remains excellent value on the used market.

Looking Higher: RCF SUB 9004-AS
At the premium end, the SUB 9004-AS sits above the 8003/8004 family. It’s a touring-grade single 18″ with higher performance ceiling and advanced DSP for large-scale systems.

• High-power Class-D amplification with advanced processing.
• Digital control suited to complex, professional deployments.
• Rugged build intended for integration with line arrays.

Approx. UK price: typically £3,000–£3,300. It’s not directly comparable to the three demoed subs on cost or application, but shows where RCF is pushing the tech for pro users.

Conclusion

All three demoed subs — the 4Pro 8003-AS, SUB 8003-AS II (MK2) and SUB 8004-AS — have their place. The 4Pro is a legacy workhorse; the MK2 balances portability, cost and features; and the 8004 is the powerhouse when deep bass and headroom are priorities. The SUB 8003-AS MK3 refines the MK2 with smarter DSP and a tougher cabinet (around £1.4k–£1.5k), while the SUB 9004-AS offers touring-grade performance beyond £3k.

At Datarhyme Sound for Events, we use the RCF SUB 8003-AS II (MK2), which you hire with our Live Sound and Party DJ PA hire packages.