My "main" speakers are -3dB around mid-40s with a fairly shallow rolloff. I added subs below 25hz (72dB / oct) using an analog electronic crossover built by an audio designer who knows what they're doing. Steep cutoff below 10hz. I built a pair of 12 cu ft cabinets, each housing 1 x 18" Eminence Kilomax driver. 150 watt mono amp per sub. Corner placement behind the mains.
Crossover could be higher with a strong likelihood they would interfere with the mains (soundstage, image, details).
Nice DIY subs. But they do need a bit of extra power to compensate for their natural rolloff. (Crossover has an additional response curve to counter the natural driver rolloff in that enclosure.)
I try really hard to keep from "dropping the needle" when playing vinyl.
Crossover could be higher with a strong likelihood they would interfere with the mains (soundstage, image, details).
Nice DIY subs. But they do need a bit of extra power to compensate for their natural rolloff. (Crossover has an additional response curve to counter the natural driver rolloff in that enclosure.)
I try really hard to keep from "dropping the needle" when playing vinyl.