I built two bass subwoofers using down firing 8 inch drivers mounted on the ends of cement drain pipes that were fast and tight. I also built a folded fifteen foot Helmholtz resonator for mounting in a room corner that was tuned for very low frequencies. But these days I really do find the sound including the bass is most appealing not only without subwoofers but without speakers, without cables, without transformers, without capacitors, without house AC, without fuses. Just a small portable headphone set up. No, it won't go down to 25 Hz, but boy is it tuneful and coherent.

Geoff Kait
Machina Dynamica

Thanks! for sharing- Serge. Bass, is fun. REL makes the best subwoofer in the business.