which dual sealed subs?

[User5910]

Bag End makes an 8Hz claim with their ISUB series. Like Rythmik they maintain their 12" and 18" have the same abilities, but physics suggests otherwise. ...

Bag End has more information about 8Hz in the datasheets on some of their subs. This is from the ISUB2-18's (my bold):

RESPONSE DOWN TO 8 HERTZ: The INFRA is a no compromise technology with a great degree of flexibility. By extending the frequency response down a full octave below what is considered to be the lowest musical note, low C on a pipe organ (16 Hz), we improve the phase response and reduce the delay throughout the entire audible bass range.

HOW LOUD AT 8 HERTZ: While the ISUB2-18 will reproduce down to 8 Hz, it is not audible nor does it have enough acoustical power for you to feel it.
...
The ideal listening scenario is to have a full bandwidth 8 Hz playback system and play a good recording without low frequency noise present on it. The playback system can then benefit from the improved phase response without requiring excessive power in the lowest octave or engaging the Dynamic Filter circuit.

That said, an infra sub showed relatively high distortion in Keith Yates' 2004 subwoofer test at Sound and Vision: Way Down Deep II Bag End S21E. The details of all the tests are interesting to read:

• Way Down Deep I
• Way Down Deep II
• Way Down Deep III

I'd love to try one out. I don't live far from their HQ--I wonder if they do demos.