Ans this is the same track with the sub kick taken out.
seen from India
seen from China
seen from Bulgaria

seen from Brazil

seen from Portugal

seen from United States

seen from Kenya
seen from Uzbekistan
seen from Germany

seen from United States

seen from United States
seen from Türkiye

seen from Singapore

seen from Singapore
seen from Bulgaria
seen from United States
seen from China
seen from Paraguay

seen from Bulgaria

seen from Singapore
Ans this is the same track with the sub kick taken out.
If you have some good headphones or decent monitors get them.
This is the first test recorded using the sub-kick. Sadly the first thing I hear is the terrible kick drum, but the sound is otherwise pretty good.
Listen to this then listen to the next track with the sub-kick taken out.
So some test data. The first spectrograph is the recording of a single kick with the SM58, the second the same kick with the Sub-Kick.
Straight away it is clear that the Sub-Kick has captured much more low frequency audio than the SM58.
This first test was carried out with the back of the device in place. The later tests will be with it off.