Anyone listen to Zu Audio's Definition Mk3?

Another "full range" speaker that I heard that really blew me away (don't know why I forgot about them until now) is a circa 1940 Jensen field driver (13" cone, built in tube power supply). I heard a system that uses this driver crossed over to a tweeter at, I believe, 8 khz (all but the highest octave being reproduced by the Jensen driver). This is the best overall sound I have heard from a full range or nearly full range single driver system. There was very little of the midrange peakiness of full range drivers--the sound was rich and warm and good with even large symphonic works (a problem for other full range drivers like the Lowthers), and bass was surprisingly decent. It is VERY unfortunate that this is an extremely rare speaker and there have been no successful attempts at cloning this driver.

Charles, just spoken to Sean at Zu. Their top option for cap upgrade to the Def 4s tweeter is the Duelund VSF Black Cu. He's not familiar with the CAST and hasn't experimented with it. So the Black VSF is where I'm going.

Spirito, since my Def 4s are under construction and Sean says their top option for cap upgrade to the tweeter is the Duelund VSF Black Cu, isn't that something I should have him install? Why o why doesn't he install that cap fro the get-go? $$? Why are you seeking a cap upgrade, and how did you figure out it was a cap you needed?

Spirit,
The VSF Black is the model just below the CAST and is thought to be one of the finest capacitors available. I think you`ll be very pleased with your results.The quality of cap matters a lot in terms of maximizing sound. If it did`nt, Zu would`nt bother with offering higher level upgrades.
Regards,

Warrenh, first off, you're going to be SO stoked with your 4s (and I suspect your wife may be just a little pleased too)! Despite my original reservations that the tweeter wasn't a night and day upgrade in the 4s over the 2s, I've done a 180 on this - in fact the higher frequencies are to die for. But, it took a LOT of adjusting to get the 4s to sound of their best, incl. from the tweeter. Hence, I wasn't at all feeling I was missing anything. But Charles has put the cat amongst the pigeons in expressly stating that a cap upgrade will extend the sq of the higher frequencies further. At the likely price of c.$1000, it seems like a no brainer to squeeze out maybe a last 5% of performance. If I was going down an amp upgrade, I would hold off on this, but I'm really happy with my Hovland amp/Def 4s synergy, and so this is the logical road to go down to improve performance envelope further (save for possible Zu Event power cords/replacement of stock spikes).