Thanks for the update on your thread, Trevor!
And yes indeed, those Eve SC-407's are really classy speakers. Exceptional, I think. As you noticed, they have a clarity and depth that is not common in speakers in that price range.... That's actually true of most of the Eve speakers.
The "secret" is partly in those strange tweeters: they are unlike any other tweeter (except the ones that Adam uses). The technology is totally different from conventional tweeters: most tweeters have either cones or domes made from some type of very light weight, very rigid material. It has to be light, so that it can accelerate and decelerate very fast (forty thousand times per second!), but even with the best materials available today, they are still not rigid enough and light enough: the surface of a typical tweeter doesn't all move together: it wobbles and trembles and resonates and "breaks up", with different parts moving at different speeds and in different directions. If you look at a slow-motion video of the way a tweeter actually moves, you'd be shocked! So the sound wave it produces is not clean, precise, and well defined, since it does not emanate from the entire surface of the tweeter smoothly.
But the Eve tweeters use a very different concept: something they call "AMT" for "Air Motion Transformer" (Adam uses something very similar, that they cal "ART"). The technical name for this is "Heil Effect", named after Dr. Oskar Heil (the same guy who invented the FET, or Field Effect Transistor... which you are using right now, since your computer or cell phone undoubtedly has a few million of those things inside.... but I digress). Anyway, about 60 years ago, Dr. Heil came up with the concept of the Air Velocity Transformer, which looks something like a miniature concertina or accordion, usually made from a thin, very light weight, paper-like material with thin metallic foil strips applied to each pleat, and mounted in a strong magnetic field. The principle of operation sounds a bit weird, but works extremely well. When you apply voltage to those foil strips, they either attract each other or repel each other, depending on the polarity of the voltage. And as they do that, they force the folded "accordion" pleats to either squeeze out or suck in air between them. Now for the kicker: that "squeezing out" and "sucking in" is five times faster than a normal tweeter can move! Conventional tweeters move air at a one-to-one ratio: the amount that the tweeter dome moves, is the amount that the air moves. The speed that the tweeter dome moves, is the speed that the air moves. And as you probably know, there's a huge difference between the speed of the dome itself, and the speed of sound... in other words, there's a very large impedance mismatch. But with the AMT method, each "squeeze" forces out five times more air, five times faster, so it has a major advantage over a typical tweeter.... and it can also handle frequencies much, much higher than a conventional tweeter. Thus, the impedance match is greatly improved... which is why those AMT devices do not need waveguides, like normal tweeters. The purpose of the waveguide on a speaker, is to match the impedance of the cone movement, to that of the air itself, but with an AMT, the impedance is already closely matched, so the transfer of energy is smoother, and cleaner. The clarity in the high end is amazing, with a Heil Effect tweeter.
Adam and Eve are not the only two manufacturers to use this concept: There are others. There's even a company named after Dr. Heil that makes them. But Eve has perfected them more than anyone else, and their speakers are outstanding.
So, Trevor has now purchased himself a pair of some of the best speakers out there, at any prices, and he got them for a song! I do know the history of this particular pair, as Trevor hinted at, but I won't be going into that right now... maybe at some point...
And as you can hear from Trevor's gushing praise, they are pretty darn good speakers! They can be used either horizontally or vertically (you can remove the center section, with the mid and high drivers on it, and rotate it 90°), but for Trevor's room we will use them vertically (the way he has them set up currently) for several reasons. I actually prefer that orientation for these speakers anyway, especially when soffit mounted. Years ago I spoke to the chief engineer at Eve Audio about doing that, and he agreed that it's the best orientation for soffit mounting those, in most rooms. He also gave me some tips specific to Eve speakers about soffit-mounting them. Great guy, actually: to take the time to talk to me about one specific room, when he's also running one of the most successful speaker manufacturing companies.
If you are reading this, and in the market for new speakers, do take a look at the Eve Audio line up.
Here endeth my plug for Eve. (As most members here on the forum know, I do not accept advertising here on the forum (no spam!). That said, I don't mind talking about products and discussing their advantages and disadvantages, and this is one of those cases. I only recommend products that I know, and have proven themselves in practice, and Eve falls into that category).
Anyway, that's where Trevor is right now: a great pair of speakers, and a lousy room!
But I'll be working on a design for soffits for those speakers in his room, and it will be a bit different from typical soffits, because of some of the restrictions imposed by the room. So stay tuned to this thread! It will take a couple of weeks to do that design, as I'm also working on other projects at the same time, but Trevor is probably going to be working on other aspects of his room in the meantime... and probably also spending hours and hours in total bliss, listening to his new speakers!
- Stuart -