OK. All done!
(Reply to another CLS IIz owner who upgraded his panels about a year ago.)
Let's see. OK, I got the first panel swapped on Saturday and the first thing I did was to A--B it with the remaining old panel. Frankly, I wasn't hearing much difference between them, when I realized the new panel had zero break-in time. (I later asked Dana where the "100 hour break-in" figure came from, and he said, "that's what the engineers told him"; and so I decided to reserve judgment on that issue! As you also reported, I sensed no harshness/brightness 'out of the box' as with the earlier CLS panels. In fact, I decided to restore the 'softening' switch to its default position (no 'softening'.) As it turned out, the new panels did change, after the first 20 - 30 hours. but I'm getting ahead of myself.
Sunday, I completed the swap, and the first thing I noticed was a cleaner more robust bass. I'd forgotten you mentioned the same thing in a previous email, so I was completely unprepared for it. Having discovered four years ago, the amazing bass integration possible when combining electrostats with just a single phase-matched (omnidirectional) subwoofer placed right between the (dipole) panels, the overall bass performance took a real leap forward! The lower mid-range was also rendered clean and solid, despite weakness in that area being a criticism (for some ;--) of the CLS's overall performance in the past.
For the next 5 -- 10 hours, I was looking for any improvements in soundstage, instrument/soloist location, and frankly I didn't hear anything noteworthy. I wasn't disappointed though, because my decision to replace the panels was based principally on extending the longevity of the speakers; which, like you, I had concluded were worth keeping, based solely on their previous superior performance -- so I wasn't really looking for remarkable performance improvements, per se.
But then things started happening -- around 24 hours -- beginning Monday morning. First, a noticeable increase in low level detail (like hearing the fingers sliding on guitar strings, or lifelike rustlings in the orchestra and/or the audience, and a true "breath of life" in the vocals; these all had to be the result of improved transient response in the movement of the diaphragm itself. Or to put it another way, the diaphragm was following the music signal with even greater precision than that we ordinarily expect from electrostats (and ribbons.) The only scientific explanation for such 'improved control' of the stators over the motion of the diaphragm, would have to be the new generation of diaphragm material which, as stated in the current MartinLogan literature, has an improved conductive coating; that combined with the very likely possibility that 20 year old diaphragm coating may have lost some conductivity over time -- due to dirt build-up and/or oxidation of the coating itself -- and something longtime owners like us would not have noticed over such an extended period.
The last important characteristic to emerge, as I continue listening 50 hours and beyond, is an increased sense of shimmer or electricity surrounding the performance; some refer to this as air, or ambience, often confusing it with reverberation which is actually an acoustical characteristic of the performance space (when it's not artificially added ;--) The effect of sheer novelty makes it easy to be unduly stimulated or impressed when listening to most good loudspeakers for the first time; and I try to guard against it. However, the totality of the improvements obtained after installing this "second--generation" technology were startling, and impossible to simply write off to short term novelty ;--)
I know it may sound "overzealous" (if that's even the 'right' word ;--) but I would be very curious to compare my "new" CLS IIz's with the CLX! For now, I'm absolutely thrilled!!