The Guru speaks: Vance Dickason

Speaker guru Questions , look for driver 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. Without giving the standard "weakest link" answer, how important would you rate speakers as component?
Certainly loudspeakers are not a weak link, but they do possess more sonic variance than any other part of the chain. Just as important, however, is the sonic variance that comes from rooms and room placement. The work done by Dr. Floyd Toole's group at Harman International, which includes Sean Olive and Alan Devantier, all part of the former group at NRC (National Research Council) in Canada, has produced significant information about what measurable characteristics in loudspeakers tend to make them judged as superior. Of equal importance is how different room positions cause more significant differences in the sound quality of a loudspeaker than the fairly substantial differences you find from speaker brand to speaker brand. Of course, my personal favorite, is how sonic preferences change from a blind AB/X test to the same test performed with the brand badges in full view. How, do I rate the importance of loudspeakers in the chain? No part of the reproduction chain is less important than any other, however, loudspeakers introduce the element of subjectivity substantially more any other component.

2. How have speakers changed in the past ten years?
Loudspeaker design is a fairly mature discipline. There were great sounding speakers 10 years ago and there are great sounding speakers now. I think the biggest difference is that there are a higher proportion of good sounding speakers on the market than ever before. This is due to a large extent to the widespread use of computer design technology that has become available over the last 10 years plus the continued dissemination of information about professional design.

3. Do we have to spend a lot on woofers and tweeters to get good sound?
This poses and interesting question. Good sound is a function of design integrity on two levels, transducer design and system design. I produced a $25k home theater system for one manufacturer that uses a very low cost dome made in China by Vifa (only available OEM unfortunately). It sounds great in the system and has a OEM price of about $4. In terms of what's available to the DIY user, yes the expensive stuff tends to really sound better. If you work like I do and have drivers built to specification, its not hard to produce a great sounding transducer for reasonably low cost.

4. What are the top three design parameters you use? (or the top three things you worry about most)?
My first consideration is always the timbre and sonic detail in the device, which really doesn't have a parameter. But in terms of quantifiable parameters, probably SPL, impedance and the T/S parameters.

5. Do you design on measurement or sound?
Really, it's a combination of both. Using only measurements is more reliable than using only sound (listening), but either way, you can't rely on just one half of this equation.

6. What is you crossover philosophy?
I fall into the KEF (old KEF in the days of 105 and the Rogers LS35A), BMW, Mirage, PSB, Snell, M&K category and generally use only 4th-order optimized networks.

7. What to you think is that "special something" is that makes some speakers sound so good?
There is a lot of serendipity in any subjective endeavor, but if I had to pick one thing, it's the eclectic combination of driver timbre that gets you that sweet spot.

8. How many octaves does a speaker really need to sound right?
You a very musical sound if you cover the 8.5 octaves between 40Hz and 15kHz.

9. Is the bottom octave required?
No, but it adds a level of sonic impact and realism that's really great.

10. What about above 20K? There has been a lot of talk over the years about human response to the two octaves above 20k, out to 80kHz.
I have seen brain scans that seem to imply a reaction in the human mind to 40kHz and up information. However, my personally feeling is that this is a very secondary phenomenon and would only provide very marginal improvements in realism, not to mention the difficulty in defining the exactly what is meant by "realism". The brain perceives somewhat like a FFT analyzer, each person with a different perceptive "windowing" algorithm.

11. 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.

12. 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.

13. 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.

14. 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.

15. What does the future hold for speaker design?
More digital amplification, possibly located on the driver itself, more powered speakers, speakers that are IP addressable and speakers using RF instead of hard wire.

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Copyright: Peter J. Smith 2005 Return to