The Guru speaks: Vance Dickason

Driver guru Questions , look for Speaker questions in the driver gurus section.

You can use the information that was published in the Robb Report Home Theater interview I sent you, are check out my books for some more retoric and pics.

First paragraph of bio from the link above: Mr. Dickason has been working as a professional in the loudspeaker industry since 1974, when he founded Speaker Research Associates (SRA). SRA published the first and second editions of the Loudspeaker Design Cookbook and exhibited its high-end loudspeaker products at CES in 1978. In 1986, Mr. Dickason joined forces with Audio Amateur Inc. and became editor of Voice Coil, The Magazine for the Loudspeaker Industry, and a contributing editor to Speaker Builder magazine. AAI has since published the third, fourth, fifth and recently released sixth editions of the Loudspeaker Design Cookbook (published in English, German, French, Dutch, Italian, and Portuguese) as well as the computer aided system design tutorial titled Loudspeaker Recipes.

1. What was the best part of working for a large speaker manufacturer?
I am an independent consultant, so only work "with" large companies, not for them. Some are incredible to work with, like Bravox, the Brasilian OEM driver manufacturer I have represented for the last 10 years, while others, like a few of the China factories I have worked with are very difficult.

2. What was the worst part?
Communication is the biggest problem. Lanquage and culture are difficult boundaries.

3. Without giving the standard "weakest link" answer, how important are drivers as part of the whole speaker?
While you can screw up a good set of drivers with bad network design, but even great network design can't fix bad drivers. Speakers and their sonic timbre is the most important part of the speaker.

4. Can a good speaker be made with low cost drivers?

5. I mean really, there are like, ten parts in a woofer. How hard can this be?
So what are the three main differences between a $5 and $100 woofer? Again it comes down to engineering integrity. Coming up with the right balance of conditions takes not only skill, but investment in materials. You can't buy a lot of material for $5, so you have a lot of limitations, especially power handling, damping, and distortion, so these would be the three big differences.

6. Are parts mass produced and you pick them from a secret catalog?
Parts are indeed mass produced, but there is no secret catalog. A lot of speakers are made by assemblers who buy from parts vendors. This is generally the mediocre stuff. The best results usually come from conceptualizing a product and doing custom tooling to execute the design, which is obviously more time consuming and expensive.

7. 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 know the engineering staff at both companies and the are indeed very competent. I think that many times the "custom" changes are relatively minor, however, sometimes the customer can ask for very substantial changes to be made, but I don't think this is the norm.

8. Other than the standard line about stiffness, what do you have to say about cone material?
Each cone material has it's own sonic signature that is caused by the material properties such as transmission of vibration through the material, resonance etc.

9. What about tweeters, metal or fabric dome and why?
There are great examples of both, plus there are a few other great sounding materials. The Scan Speak D2904/980000 is an aluminum dome that has in my opinion one of the most musical timbres of any tweeter I have ever used. In terms of soft domes, the SEAS Millennium is by far the most exquisitely detailed tweeter I ever heard, so there is no easy answer to that question.

10. 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 crossover?
That really hasn't been my experience and I have developed systems using both low cost 3rd world OEM woofers and expensive European built products. Every woofer has its own reactive nature and it takes a lot of experience and a large bag of tricks to know what to do.

11. Are there any tip-off specs to know a driver is good or bad on paper?
Doing a computer simulation from the specs will tell you a lot about the dynamic range of the product and if the damping quality (Q) is going to where you need it to be. However, just looking at parameters without doing a simulation doesn't tell you enough.

12. Are there codes in driver descriptions to suggest this is not a great driver? No, again, just looking at specification doesn't tell you much until you get into the computer with them. Maybe the only tip offs would be insufficient Xmax or excessively high or low Qts.

13. What types of drivers are most popular?
The most common driver product still is the poly cone direct radiator, followed by aluminum, carbon fiber and Kevlar cone direct radiators.

14. What percentage of drivers sold are shielded and will all drivers be shielded in a few years?
It's pretty hard to say, but with the advent of home theater, the percentage has probably risen to perhaps half or more in home audio. As flat screen monitors begin taking over the CRT market, using bucking magnet and cup shielding on woofers and tweeters will eventually disappear.

15. What one piece of advice would you give every new speaker builder?
Gee, buy a copy of the Loudspeaker Design Cookbook, do a lot of empirical experimentation and then enjoy listening to the music you helped create.

16. When you get cornered at a party by a new speaker builder, what is the question they ask most often?
Probably how do you get into the business of professional speaker engineering, what kind of education you need and so forth.

17. Will we ever find the Holy Grail in sound reproduction?
Brent Butterworth asked me that same question in a recent interview he did with me in Rob Report Home Entertainment. My answer is pretty much "no". Reproducing the original acoustic event in another acoustic space is very difficult and the best you can ever hope for is a good approximation. I think it's rather like questing for the impossible dream, Don Quixote, windmills and that sort of thing.

18. So which is it, tubes or SS?
You mean is it tubes, solid state or DSP? Up until recently, I would have said that analog rules, but having worked a bit with the new DEQX digital crossover system and hearing it driving some nice SEAS drivers with Power Physics digital amps (the new NHT Xd system), that line is getting very blurred. I am a musician and amateur radio guy from my youth and own a ton of tube gear (guitar amps and vintage shortwave radios), but I am not one of those who believes that solid state and digital takes the soul and passion out of music and the tubes are the only way to go. Tubes sound great, but it's hard to get away from the noise. Kind of like vinyl records sound great, but its hard to get a away from the noise. From my perspective, all three, tubes, analog solid state and digital solid state are capable of providing a very satisfying audio experience, so its ultimately user preference.

19. What does the future hold for driver design?
More and more effective computer simulation.

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Copyright: Peter J. Smith 2005 Return to