After ten years of use, the original horn in the Phoenix had grown weak and sounded more like a scooter than a six-ton motorhome. This wasn't about aesthetics or wanting to “make my little car louder” — it was about safety. The horn is the only way to alert others in traffic by sound, and on a vehicle of this weight it should be audible even over highway noise, the open windows of a neighboring car, or the music in the cabin of the driver you're trying to warn.
I decided to replace it with the Stebel Nautilus Compact 12V Chrome electropneumatic air horn.
Why the Stebel Nautilus Compact specifically
The Stebel Nautilus Compact is an electropneumatic air horn with its own compressor — unlike ordinary electromagnetic horns, it generates its own air for the sound tone, which is why it sounds noticeably stronger and fuller. The specifications that convinced me:
- 12V power supply, current draw of approximately 18 A
- Harmonized dual tone of 530 + 680 Hz
- Sound pressure level of approximately 115 dB at 2 meters
- ECE homologation for use in road traffic
Installation — why it requires a relay and a thicker cable
A draw of around 18 A is significantly more than the original switch and the thin cable routed from the steering wheel can handle. That's why the Stebel — like most powerful electropneumatic horns — isn't wired directly, but through a relay: the original switch in the car only switches a small current to the relay coil, and the relay itself then switches the power circuit, routed with a thicker cable directly from the battery and protected by a separate fuse. This wiring setup is necessary not just for it to work, but also for safety — without it, there's a risk of overloading the original wiring and switch.
The physical installation of the horn body itself was, by contrast, uncomplicated — finding a suitable spot in the engine bay, mounting it, running the wiring to the relay and fuse box, and connecting it.
How it sounds in practice
The difference compared to the original horn is dramatic. The 530+680 Hz dual tone is audible even in situations where the original horn would have been completely drowned out — on the highway, in heavy traffic, through an open window with music playing. That was exactly the goal of this upgrade.
Rating
★★★★★☆ (5/6)
For what it costs, this is one of the best safety upgrades I've made on the Phoenix — it ranks alongside things like the Marquart shock absorbers, and the gearbox and differential oil change, which I did on the same day. None of them are visible at first glance, but all of them have a real impact on how safely and reliably you can drive the vehicle.
📦 Components used
- Stebel Nautilus Compact 12V Chrome (electropneumatic air horn, 530+680 Hz, ~115 dB/2 m, ECE homologation)
- Automotive relay + separate fuse for the power circuit
Source of the product photo: Auto-Majáky.cz
Frequently Asked Questions
How loud is the Stebel Nautilus Compact and why is it different from a standard horn?
The Stebel Nautilus Compact is an electropneumatic air horn with a sound pressure level of approximately 115 dB at 2 metres. A standard electromagnetic horn reaches 100–107 dB. The 8–15 dB difference is significant in practice — the air horn is heard through closed windows of a neighbouring car and motorway noise.
Why does an electropneumatic horn need a relay and thicker cable?
The Stebel Nautilus draws approximately 18 A when activated. The original steering wheel horn switch and thin cable are rated for 5–8 A. Without a relay, the cable would overheat, the switch would be damaged, or the fuse would blow. The relay takes over the power circuit while the original switch only controls the relay coil.
Is the Stebel Nautilus Compact approved for use on public roads?
Yes — the Stebel Nautilus Compact has ECE homologation, which permits its use in road traffic in EU countries. The dual tone 530+680 Hz complies with the requirements for audible warning devices for N-category vehicles (trucks and motorhomes).
How many amps does the Stebel Nautilus draw, and what relay to use?
The Stebel Nautilus Compact draws approximately 18 A at 12V. I recommend a relay rated at least 30 A and cable with a minimum cross-section of 2.5 mm². Place the relay as close to the battery as possible — a shorter power cable reduces voltage drop and the risk of overheating.