In this forum a low frequency horn sub has been mentioned, I have simulated it with a JBL 2226 H. (Hornresp by David McBean)
It goes down to 18 Hz (-10 dB) and is very flat until 22 Hz (-3 dB). It is simulated for use in a corner but placing in front of a wall can be compensated by slightly increasing the bass by tone control.
It is huge, 2134 liter netto, about 2600 liter brutto. Living in a house for your own it will perhaps give you a corner place of 1 square meter with a height of 2,70 m.
The horn length is 5,8 m and the horn mouth is 12200 cm*cm, a bit more than one square meter.
Efficiency is about 108 dB/ W /m, max SPL with 600 W at 100 Hz will be about 137 dB.
Omitting the 200 liter (!) rear chamber volume will produce irregularities in SPL. Increasing throat chamber volume (in front of the cone, same area) will make the high frequency roll off steeper - due to cone excursion it can't be made smaller than 1000 cubic centimeter (1 liter).
The pictures show you in detail:
1. Input parameters (JBL 2226 H)
2. Overview (Schematic diagramm)
3. SPL responce (corner/ 0,5 x Pi)
4. SPL response (wall/1,0 x Pi)
5. Electrical impedance
___________
Peter
PS: The shown SPLs are 8 dB too low.