Description from the Funktion-One website:
Funktion One are renowned for the controlled energy of our loudspeaker systems – this is nowhere more evident than in our bass enclosures which deliver physicality with accuracy for truly involving musical experiences. In the 1980s Funktion One’s Tony Andrews pioneered work on the development of the first 21” loudspeaker ever made. This provided the low end for his highly regarded system design of the time which was used on world tours by groups including Pink Floyd and Dire Straits. More recently, with F1’s access to advanced materials and Andrews’ heightened understanding of loudspeaker and enclosure tuning, his original 21” concept was due for a revisit. The Funktion-One designed drivers are incredibly robust and have 6” voice coils for maximising power input. The powerful Neodymium magnet provides very high magnetic flux density whilst significantly reducing the weight compared to ceramic. The resulting F221 is an exceptionally efficient high-intensity bass enclosure providing fast, accurate, physical bass of the highest calibre.