Have had this sub for 25 years. Dual 12’s in a very (relatively) compact box. Measures pretty darn flat and only 3dB down at 20Hz in the nearfield, without any DSP or EQ trickery.
Just wish I could find a used one for sale so I could have a matched set, but they didn’t sell a ton back in the day due the higher price. My odds of success are quite low.
Pinnacle Digital Sub
I went through all the steps, then it vanished. I posted it as a separate post, and the hot removed it.
Reddit hates my subwoofer