John Bau: Interstellar Overdrive Page 5
I don't know of anyone who could hit on problems as directly as he could, and had the wherewithal to devise a measurement technique that would, that could give you accurate measurements, even in a very small room (admittedly, then, not down to low frequencies). There was no other single source of information that was as helpful in getting me on what I felt was the right track. I just feel an amazing devotion to him.
Atkinson: I remember going to a talk he gave in London where he presented the idea of the hi-fi experience as being multidimensional. The reproduction of music involves five, six, or more separate parameters—as many as you care to identify and map out, in fact—changing instantaneously at any one time, time, of course, also being a parameter. But if you want to measure that performance, you can only really plot one parameter against another, or one parameter against two parameters if you have a 3-D analyzer or 3-D display. Any one measurement can therefore only give you a tiny part of the whole picture.
Bau: Right. I mean, part of what he's talking about there is the psychology of musical perception. I really appreciated that part of his work, but I couldn't embody it in any way. I had to draw the line there, as I wasn't in a position—again, because of my lack of formal training—to be able to evolve new ways of looking at things. Since we were so far away from having systems that lived up even to these simple things that we can measure and correlate, we can only do the best we can with the problems that are there—to optimize. If there's word that sums up Spica, it's "optimize."
Atkinson: One continuing aspect of Spica loudspeakers is that you choose to utilize what are basically not particularly esoteric drive-units, but then concentrate on getting the best performance from them. Do you think that, on the whole, too much emphasis is placed in hi-fi on obtaining very complicated high-tech solutions to some problems but ignoring others totally?
Bau: Sure. I think that's a problem of our age. Not just hi-fi, frankly. But yes, it's very true. I'd like to make one comment on our tweeters, because if there's any criticism that we get consistently, it is that we're using a tweeter that is sort of old technology. We get samples from all these companies and we check them out pretty thoroughly. Again, because we don't design to suit our ears, we don't really do extensive listening tests but we sure put them through the ringer on the bench and out in the test box. And we just have not seen a better overall unit.
And one of the very important key factors—and it's going to be true even on a three- or four-way system—is that we need as much overlap as we can get, a minimum of two octaves. Otherwise there is no hope of creating a good phase-aligned system. The nice thing about the Audax tweeter is that if you put it on a reasonably sized baffle, you've got a 3dB-down point around 600Hz. So if you're crossing over about 2400-2500Hz, you've got three octaves of accurate crossover.
Atkinson: I assume that it is also helped by the fact that one listens to your tweeter off its own axis. If you stand up in front of the Angelus, for example, then you hear a lot more treble energy.
Bau: Sure, that helps a lot. Another thing that it really helps, something that we really haven't articulated clearly in the past, is that every driver has an area where its high-frequency response starts to beam, to narrow. Most systems are optimized so that the listener listens on that beaming axis. The designer is trying to take advantage of that extra energy in order to get an extended response. For what, I don't know. One of the things about using the drivers the way that we do is that that's an exception. Most of the response of the driver is not that beaming characteristic. And if you design a crossover network for that characteristic, all of a sudden you've got this huge suckout off-axis! So if you optimize a system for the norm and not for the exception, then your energy response in the room ends up being much more linear as well. You can walk around the room and the tonal balance doesn't change all that much, given expensive rooms.
Atkinson: The National Research Council in Canada pretty much determined that severe peaks and dips in the off-listening-axis response of the speaker will, in a real room, result in audible problems.
Bau: Sure, because your reflections coming off the wall sound different from what you're getting directly. What we're trying to describe here are subtle psychological distractions from an original event. It's a problem that we have to listen in rooms, as far as I'm concerned. That puts a heavy burden on open-panel systems because, to me, they don't even appear to be designed to be used in rooms. When I lived in Minnesota I heard some of the earlier Magnepans in a huge room and they sounded magnificent. In a big room, the antiphase energy bounces off the back wall and comes back to the listener so delayed and so low in amplitude, due to the inverse square law, that it doesn't degrade the purity of the direct sound. But when I heard the same system in a dealer's showroom, it sounded awful.
Atkinson: Will it be another five years before the appearance of the next Spica loudspeaker?
Bau: We're creeping up to our flagship. We've been going around and around with a driver manufacturer who has a quite nice solution that reduces distortion components in the region of the low-frequency driver resonance by like 20dB. It's astounding. You can tell the difference without even putting the drivers in the box. You just hook up one of his and take any other driver you've got and put low-frequency tone through them; this one moves just totally noiselessly and totally linearly, whereas the other has got all other sorts of stuff in it. So I'd like to incorporate that driver into our next system. But he hasn't been able to give us what we want yet. He's still trying to convince us to use reflex boxes! So until we can get from him what we want, we can't really proceed.
We're focusing more and more on the quality of the drive-units, on cabinet construction techniques—it's only been in the last two years that we've got a cabinetmaker that can give us what we need at a price that we can afford. I don't come from a wealthy background; the sort of person I want to serve is one who really loves music, wants to hear what's there, but doesn't have an unlimited supply of funds to spend on it. As objectively as possible, I think that the Angelus, just looking at the cabinetry, is an amazing bargain. You just don't see things like that for $1000. There's a lot there. I really don't know how to do a better $1000 speaker than that.