Driver Guru Questions
One of the first graduate student pioneers to emerge from MIT's Media Technology program in 1981, Ken Kantor has enjoyed a celebrated career as an technologist, entrepreneur and designer for the consumer electronics and broadcast technology industries.
A. What was the best part of working for a large speaker
Learning from others. In two years, you learn as much as you otherwise would in ten. In ten years, you learn what it might have taken a lifetime to discover. Plus, you learn discipline, the skill of integrating diverse input, and the ability to deliver a finished product.
B. What was the worst part?
The years of getting in to the office at 8 am, every day.
C. Without giving the standard "weakest link" answer, what are
the most important speaker components on which to spend money?
If you mean components of a driver, clearly the "soft parts," spider, cone and surround, come first. Glue is next. But, remember, the detailed assembly process is often just as important as the materials.
D. What about crossover parts and specialty caps and the like?
Not particularly cost effective, in the scheme of things. In fact, sometimes they make no difference at all.
E. Can a good speaker be made with low cost parts?
Sure. And lousy speakers can be made with the best parts available.
F. I mean really, there are like, ten parts in a woofer. How hard can
Picking which ten parts is the trick. There are many, many performance tradeoffs to be made. Once you have figured out what you want, it isn't that hard. A world-class, automated driver line can produce a decent speaker in less than 4 seconds. On the other hand, even the temperature of the room as the glue dries can have a profound effect. Process control is very, very critical.
G. So what are the three main differences between a $5 and $100 woofer?
Consistency, power handling, sales volume.
H. A lot of speaker manufacturers say they use "custom
designs" from Vifa or Seas. Are they really custom or just small changes
made to stock drivers?
I. Other than the standard line about stiffness, what do you have to say
about cone material?
I didn't even know there was a "standard line." To me, cones are complicated things. Am I missing something?
J. What about tweeters, metal or fabric dome and why?
As Emerson put it, "A foolish consistency is the hobgoblin of little minds." There are fantastic speakers that have been made with both types. Why are audiophiles sometimes so afraid of using their ears instead of their eyes?
K. It seems like expensive woofers are harder to tame than cheap
woofers. How come so many expensive woofers are so hard to tame in the
I'm not sure this is true. Perhaps people just expect more from the expensive woofers. I suppose that, to some extent, expensive designs try to differentiate themselves by using atypical materials and construction. There might be certain negative consequences of this.
L. Are there any tip-off specs to know a driver is good or bad on
Not really. Of course, most speaker designers will find it easier to get good results from a driver that measures generally flat. Unfortunately, you never really know how the measurement is done, and how it relates to your system goals.
M. What types of drivers are most popular?
Ones that put out. Next question.
N. What percentage of drivers sold are shielded and will all drivers be
shielded in a few years?
In the "commercial" world most tweeters and many smaller woofers are shielded. It's hard to shield larger woofers, and less important in most applications. The DIY world generally is not as compelled to pay extra for shielding. My guess is that as LCD and Plasma displays become more ubiquitous, shielded drivers will actually become less common.
O. Will we ever find the Holy Grail in sound reproduction?
Not inthe world of drivers, that's for sure. It's a system issue, if anything.
P. So which is it, tubes or SS?
As I said above: tubes are for guitars. It's very, very hard for me to imagine that one will even be able to purchase a tube in 10 years, besides precious totems, swathed in velvet and cupped in the hands of high audio priests.
Q. What does the future hold for driver design?
The history of consumer audio, going back 100+ years, has a powerful thread of continued product integration running though it. People want their devices small, simple and powerful. Driver technology needs to support this, allowing the most output from the smallest space, and allowing high performance sound to be incorporated into the kinds of products people want to own. This might mean 100 Hz from a laptop or 10 Hz from a compact subwoofer. Humans love music, and wherever you can deliver it to them, they seem to want it.
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Copyright Ken Kantor, 2005