Years ago I tried to build an active sub for my ESL63s. It was based on a Goodmans Magister cabinet and 15" driver, and it was a failure. Fast forward to a couple of years ago, I got a car sub amp and XO, a couple of sealed box car 12" subs (Vibe brand IIRC) and bodged together a chunky 12V SMPS. Stuck it all on the carpet behind my ESL57s. It was only a bit of fun, I expected to throw it away after a play. Guess what? It integrates perfectly, the only debate is how much bass reinforcement is required. I favour very little, a pal of mine with monster Tannoys with 2x 15" HPDs *each* unsurprisingly favours a little more.
Maybe I just got lucky, but it works.
Maybe I just got lucky, but it works.