Siblings in ELAC's Navis series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | evenly matched | Much the same reach (43Hz vs 44Hz). |
| Built-in power | evenly matched | Similar onboard amplification (300W vs 300W RMS). |
| Connections | evenly matched | The same set of inputs and streaming options. |
| Size | depends | ELAC Navis ARB-51 is easier to place; ELAC Navis ARF-51 is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Powered Floor-standing against a Powered Bookshelf - a different job rather than a better one. |
| Price | B | ELAC Navis ARB-51 is cheaper - $1,998 against $3,798, about 47% less; arguably a different class. |
A ELAC Navis ARF-51 B ELAC Navis ARB-51
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. In a large or open-plan room, ELAC Navis ARF-51 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, ELAC Navis ARB-51 is the easier speaker to get right. Think about the whole system, not just the speakers: the roughly $1,800 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.