These subwoofers are rubbish – not as bad as open baffle (which simply cannot pressurise a room), but worse than bass reflex (and that’s bad enough). 😀 For proper sealed subwoofers that really work, try here instead.
They have “Hopeless” (or should I say “without peer”?) 12-inch 8 Ohm “extra long stroke” twin magnet drivers from one of those Danish companies that used to make great drivers but now have them made cheaply in China. There are matching passive radiators in the back.
The enclosures are of 32mm MDF with a 3mm Fijian Cedar plywood “veneer”. Performance is awful – hopeless dynamics, muddy definition, no punch and they wobble around in use due to the large 625g mass on the drone and have very poor bottom end extension even when used together for 6dB gain. They are driven by a 300 Watt/channel Crest VS1100 power amplifier which drives other subs very nicely. Other speakers I have with tiny 8-inch bass drivers sound better than these!
They were built exactly as recommended by the transducer manufacturer and I use an ESP Project 99 active 36dB/octave high-pass Butterworth filter in front of the power amplifier to limit cone excursion below 17 Hz. Everything was done according to the manufacturer’s recommendations but at the end of the day junk is junk.
High linear cone excursion on hopeless low-efficiency drivers like these amount to nothing acoustically. They made pretty ornaments and for a good excuse to lift those valve mono blocks off the floor though:
Don’t worry. That equally junky amp above it is unrelated to the sub.