Anyone want to speculate what it might be? ...BC said it addresses one of the most significant problems with speaker designing.
If we're going to play Guess, let's get all the known facts on the table.
1. Cheap upgrade. I think someone mentioned under $300 per pair. (Most companies can't *sneeze* for under $300).
2. Anyone can do it, with a screwdriver and (presumably) the new part(s).
3. Smoother sound, according to one reviewer. Vague references to improved imaging.
4. Solves "a big problem" in speaker design.
5. It's nothing trivially obvious because a LOT of bright minds spend all day fretting over nothing but this very question.
6. It's patentable.
7. Brian installed an early version *while JC sat there with his eyes closed*, so it doesn't take days to integrate - just minutes at most. Which means it isn't hours of fiddly adjustments and micrometer work.
Imaging improves if you improve the phase matching of the drivers. The only way I know of to make a speaker that preserves phase perfectly is to have a single driver, and the only driver I know of that handles 20-20k well is made of electrically charged plasma, and I don't think anyone's built a working plasma speaker for $300.
I can imagine a circuit that samples the output of the speaker and makes guesses to correct the phase relationships on the fly. But I can't imagine it for less than $300. A good, sensitive microphone alone runs that much and more.
What can you do for $300? Well, drivers costs less than that, and you can replace a driver with a screwdriver, so it could be a new kind of driver. But Brian buys drivers (albeit to his own specs, if I remember) - and if a manufacturer of drivers had a improvement of real significance, even if someone else designed it and it was still hush-hush... there'd be rumors out. Somebody's stock price would be up.
Besides, replacing most of the drivers on, say, an RM/x has to cost over $300/pair. And it would take crossover adjustments, probably more than you can do with two pots.
What about a new crossover? BC's crossovers already use hand-shaved caps and other high tolerance parts, if you dish out for it. And there are WAY too many EE's out there studying crossovers for me to think that there are any cheap improvements left in that area. $300 doesn't even cover the parts in one of BC's high end crossovers. If it *is* a whole new crossover design that, say, leaves phase utterly alone, provides a flat load to an amp and has no tendency to varying sensitivity at different frequencies, then Brian is going to be very rich, everyone else is going to be very sad, and I'm going to be very startled. Happy, but startled.
What about some sort of wave guide attachment? Without snide comments about Bose, something could be bolted onto a cabinet to change diffractions and so on. But there's prior art in that area, and besides, the RM/x's claim to fame is that this problem is pretty well licked. But a new "shape" is something that could be done for $300... so I still wonder about this.
Getting drivers not to interfere with each other could be interesting... but I can't see an easy way to isolate them sonically, better than they are.
Cabinet resonance? Only cure for that is weight and sound absorption, and while weight is cheap, it's not patentable. Besides, the RM's are already good in this area. There's not too much to cure and plenty of prior art in curing it.
Maybe a whole new cabinet material? Not for $300.
What about driver surface flexing and breakup? A new coating for the midrange panels to make them stiffer? Not without adding mass to the driver. Maybe an untrathin plate of something (metal turned out to sound harsh, maybe it's mica's turn...
), but no, that's not field installable. At least not by me.
Bottom line, if I knew as much as Brian did about design, I'd build speakers. I just don't know enough to outguess him, though it's fun to try. I'll have a good laugh at myself when he announces, and I look back at this list and realise how ignorant I am.
