The term Ripole is short for Axel Ridthaler dipole as the man who patented the precise geometry of this folded open-baffle bass alignment. It works as a velocity converter not pressure generator and changes the typical 'figure 8' dipole dispersion to something closer to a cardioid pattern. This means less output at the front wall, more toward the listener still with the classic lateral acoustic short circuit of anti-phase cancellation which effectively eliminates the side walls as reflective contributors. The close-proximity loading of face-to-face woofers and the instant barrier against their back waves then seriously lowers the drivers' resonant frequency to want a compact enclosure.
Since the Ridthaler patent expired, we've seen standalone Ripole subwoofers or speaker-integrated such bass systems from Bastanis/Zugspitz, Cygnus, Ecobox, ModalAkustik, sound|kaos and Voxativ, all more esoteric brands than mainstream so not helping the cause's visibility much. At Axpona 2025, Børresen teased the mid model of a three-deep range of active Ripole subs. This screen capture from a Jay's Audio Lab video shows the stackable 4 x 8" version.
I long wondered why unlike the expired Oskar Heil patent for the air-motion transformer, the expired Ridthaler patent hasn't spawned a more enthusiastic adoption of the now free-for-all invention in the hifi scene. With Børresen starting to promote it in active guise in the costly high end of €20K/ea., this underground solution for superior bass timing without the ubiquitous room-induced ringing seems finally poised to go above ground and gain a new level of respect. After all, Børresen speakers have a well-deserved rep for very high resolution, speed and accuracy. Subs that can continue those qualities seamlessly aren't exactly common. I find it an exciting prospect that more people will discover what I've been enjoying for years already. Pass it around. Happy days in the bassment. To hell with boom boom.
Should the above video's explanations leave much to be desired, the Ripole principle isn't just about strategic dispersion to create a certain directionality. It's about superior self damping from face-to-face woofers connected in phase at very close proximity. That's very different from typical panel dipoles whose drivers face free air. But invoking far less room gain than omnipolar sealed/ported bass not only lowers their types' resonant ringing but also output. That needs compensation with greater cone surface like dynamic open baffles do. The anti-phase short circuit of a Ripole's dispersion pattern also recommends against typical corner placement. Hence there are a number of distinctions vs. classic box bass. As far as I'm concerned, it's demonstrably different. For 2.1/2.2 music systems reliant on accurate timing from proper stoppage, I find it superior. That differs from ultimate slam reliant on pressurization as home theatre might want it. That's a different game and also might want even more extension into the realm where we no longer hear discrete pitch but feel mere pressure. It's why Michael Wydra of ModalAkustik who actually collaborated with Axel Ridthaler on his model calls his Ripole sub the MusikBass. That's exactly what it is.
