The last couple of minutes of the slow movement of the Mahler Fourth Symphony represent one of those pieces of Mahler magic, often built on an extended harp solo, where time seems almost to stop and a vision is presented of heavenly beauty. Such passages have an overpowering impact in concert—when things are going ideally, one is all but out of this world for a few moments. Somehow, this seldom works quite so well in home audio. People are always talking about the difficulty of reproducing the “big moments,” the gigantic climaxes, of the Romantic and post-Romantic orchestral repertoire. But the moments of delicate beauty are equally hard to reproduce, and perhaps even more appealing if done well.
Listening to this passage on the JansZens at close range was an experience remarkably close to the magic of a live performance. Or so I found it, and not just on this occasion specifically. The zA1.1s have, to an extent remarkable indeed, the ability to reproduce the beauty of live sound, especially in top-end purity. To look at, they are just box speakers of moderate size. But there is magic in those boxes. However, the sound of them, and indeed the whole idea of them as I understand it, is something unusual, particularly as far as the radiation pattern in the higher frequencies is concerned. They do admirably what they are intended to do—more than admirably—but what that is may be a bit of a surprise, as we shall get to later on.
While the JansZens present any number of identifiable audio things well, the specific source of their fascination, their “star turn,” is their treble. It has always been an article of faith in audio that the midrange is crucial, but of course the shape of midrange frequencies, their definition and transient behavior, and their harmonics all live in the upper frequency range—from, say, 1kHz on. And this range in the zA1.1s is in effect covered by the electrostatic unit alone. (The crossover from the bass/lower-mid drivers is at 500Hz, first-order.) The treble has a combination of definition, purity, and freedom from grain and distortion that is absolutely of the top class.
In fact, so extraordinary is the treble that one is led to rethink the whole question of the top end of CDs and, for that matter, vinyl. Now I am not suggesting that high-bit-rate digital is not worthwhile. SACD for instance still sounds better than the corresponding material on CD. But people may be surprised how much of what they took for grit and grain and impurity in the top end of CD sources was in fact the graininess of typical dome tweeters.
Some time ago, I wrote in TAS that metal-dome tweeters were like bloodthirsty beasts roaming the hi-fi jungle. Dome tweeters are better than that now. But electrostatic tweeters remain special in my view. For reasons that are not entirely clear to me technically, membrane tweeters sound purer and cleaner. And yes, more resolved. The opening of John Eargle’s Delos recording of Wagner’s Flying Dutchman Overture comes to mind. One hears the repeated notes in the high strings with unusual precision, so that accurate rhythmic unanimity is preserved. With dome tweeters there is too often a certain smear; while the dome lets you hear what is happening in literal terms, the picture is slightly fuzzy. This effect is also really evident on high percussion. Cymbal crashes can seem a special weakness of CD digital—and to some extent they are. But not so much as most dome tweeters often suggest.
I am not trying to imply that the best dome tweeters are not really good drivers. After all, I have been using as a “reference” for some time the Harbeth Monitor 40s (original version), which have SEAS Excel tweeters. And good tweeters they are. But the electrostatic treble has a different character, and many people find it addictive and realistic in a way that escapes dome. At THE Newport Show just past (2015), a designer, who shall remain nameless I suppose, given that I do not have permission to identify him (it was not Janszen!), said to me: “I’ll never design a speaker with a dome tweeter again.” (His new speaker had a ribbon actually—same idea, that membranes rule the treble roost.) One can get the point once one starts to listen to the differences carefully. Which is right and in what sense? Hard to say, but different they are, in part because their radiation patterns are different.
Truth to tell, I think the electrostatic tweeter here even has an advantage over most ribbons, which tend to have a sight suggestion of the metallic somewhere in their range. The electrostatic tweeter in particular has the advantage of being made of a material with no real resonant signature of its own (Mylar film does not really have a sound), and while in principle the film’s behavior is chaotic in micro-structure (though pistonic in its basic motion), in practice the results are really superb, unexcelled in my experience (except for the legendary and totally impractical Tolteque plasma speakers, which moved the air directly but without horn loading, and therefore required truly vast amounts of power).