JansZen Electrostatic
(1954 - 1975)

JansZen owner here !
Well... I don't use my JansZen anymore but did for about a decade, with much pleasure.

My own were a swiss version manufactured by Zürich-based BOPP in the early 1970s: the filters were built far better than the originals from Neshaminy and the enclosure was sturdier. The EMT woofer wasn't very good however and as its surrounds started to disintegrate, I swapped them for fast Fentons which had the added advantage to not be too efficient - for a better match with the cells' fairly low SPL. The BOPP Model 704, like the original JansZen Z-410HP, wasn't free of annoyances but careful room-matching (tedious but worthwhile) and some tweaks helped a lot.

Most problematic was a pronounced dip in frequency response between the 25cm woofer and the JansZen array, around 700Hz. Also, the sweet spot was rather narrow - make that quite narrow. If the use of a Behringer parametric EQ treated well the first problem, the sweet spot... nobody could change that :) The need for a very powerful amplifier was taken care of with the use of first a Marantz SM-80 and then a Sony TA-N80ES. But when I decided to restore my Model 704, re-do the filters, go with bi-amplification and all that, I bumped on quite a few disagreable things, the largest of which was the very price of such a restoration :(
I sadly had to drop the matter, and the JansZens, to pursue my music listening with more user-friendly loudspeakers... But I do regret the wonderful qualities of the JansZen cells: speed, definition, depth. I still have the eight cells, just in case I were to feel like launching a DIY hybrid system - someday.

The present JansZen company is doing well and has a very complete history section on its own website. You should be able to find almost everything about all JansZen loudspeakers (and variants) at The Audio Circuit, website of which I was an early contributor regarding JansZen (some twenty decades ago).