The Speaker Guru speaks: John Nail

Speaker Builder Questions

bio: I am an avid audio enthusiast and music lover. I design and build loudspeakers as a serious, highly involved, hobby. I began in 1995-96 with a 3rd Edition copy of Loudspeaker Design Cookbook and a TI Scientific Calculator. I got computer gear in 1998-99, starting with Harris Tech's BB6 and XO Pro. I still have both of those programs and keep the databases current. I added CLIO-Lite in 2000 and then upgraded to CLIO-win Standard in 2003/4. I later stopped using XO Pro and have since been an LspCAD user since April 2004. I very much love that last program, it is very accurate. By trade, I am a Diesel Fuel Injection Specialist, factory-trained in Bosch Common Rail, Duramax, Ford Powerstroke Diesel, and Electronic Engine management/Diagnostics. I have been in the fuel injection business since 1981. I live in a little town in the south-eastern corner of Washington State. I am an amateur musician in garage bands, bar bands, etc. I have nearly 15 years of formal piano. I am married to a lovely woman, Rhonda, who is totally tolerant, almost over-indulgent, in my speaker project habits. In the "Speaker Guru" section

1. Without giving the standard "weakest link" answer, how important would you rate speakers as component?
I would have to say that speakers can be the single most import part of the audio system. With today's technology, CD player, amps, preamps, etc, have all been refined so that even getting entry-level stuff can produce good results. The final piece to the puzzle is the speaker, and I think that not nearly enough time was spent on that part of the system, at least when referring to mass market stuff. Most of those speakers just don't sound very good right out of the box although there have been exceptions. The sound the speaker puts out can make the rest of a good system end up sounding bad.

2. How have speakers changed in the past 25 years?
Other than materials and maybe a few new techniques for testing and assembling, speakers as a whole haven't really changed all that much over the past 20 years.

3. Do we have to spend a lot on woofers and tweeters to get good sound?
No way! Careful selection of drivers that have complimentary characteristics is more successful for achieving "good sound". Take a look at the GR-M130. Cheap, some would even call it a little on the chinsey side when compared to other more costly drivers, yet it shines like the real gem it is. It mates well with a bunch of lesser priced tweeters and gets a really good results. That's the exciting part of the DIY hobby. Getting that $$$$$$ speaker sound for a few cents on the dollar.

4. What are the top three design parameters you use? (or the top three things you worry about most)
I would like to say something technical, but it really isn't that at all. I look at what most others look at initially: Qts, BL factor, Fs, Vas. Of all of those, Qts, Fs, and Vas would be the most common.

5. Do you design on measurement or sound?
I design by both sound and measurement. I start with simple T/S parameters that are measured from the actual drivers to be used, then come up with an appropriate volume and alignment. I build it, then take measurements with the drivers in the actual enclosure. I also do this for the impedance measurements. Maybe this is not right, but it is what I do. The measurements are then imported and then I design, then mock together a prototype. I listen, decide on changes as I think they need to be changed, then go back and forth. Listen, tweak, listen, tweak. Then take a final measurement to verify the results to see how closely it matches the projection.

6. What to you think is that "special something" is that makes some speakers sound so good?
That is easy: neutral, natural tonal balance. Our ears are more sensitive to midrange, but the overall tonal balance has got to be right. If it isn't right, then the whole thing won't sound right.

7. What are your speaker audition strong points and weak points, i.e., what problems do you find most difficult to pick up in listening tests?
Peaks in the response. Most often, you are not auditioning in a room you are intimately familiar with, so you question what you hear. Is that a speaker peak or a room peak? Is there a cancellation just to either way in the frequency scale that makes it sound like there is a peak? An unfamiliar room makes the audition a little bit more difficult.

8. Do you have a theory on crossovers or use whatever seems to work?
I have no set theory on crossovers. Too many "greats" have come before me to figure all that out. Each topology has it's good points and bad. I guess it would all come down to the drivers that are being used.

9. Do we overstress the bottom octave and area above 20K Hz?
Sometimes I get the feeling that there is a fixation with both the top and bottom octaves. It is important to have a full range, but most listeners can be satisfied with 40hz bottom and 15K top. However, you can FEEL that last octave or so more than you can hear it, so it adds that palpability to any music. The same for the highest octave to 20K. You might not hear it with any definitive accuracy that can be tested, but just try removing that last 10K to 20K octave and see if you don't hear "something" that is missing or that doesn't quite sound natural. I would say we overstress midrange detail and resolution. The sonic image is being sharpened more and more and can be too sharp. Too sharp an edge doesn't sound natural no matter how open or "transparent" the driver is.

10. What one piece of advice would you give every new speaker builder?
The same as anyone else: Shop around, find a reputable kit and test the waters with that. If you like it, and want to go more into the hobby, then get yourself some decent software for measurement and XO design.

11. When you get cornered at a party by a speaker builder, what is the question they ask most often?
First let me say that this has never happened to me. I live in PODUNKVILLE, Washington, 250 miles south of Seattle. I haven't found one other "speaker builder" in my area unless they are "car stereo" guys. Not the same game at all.

12. Will we ever find the Holy Grail in sound reproduction?
I sure hope so. After all, if there is never any chance of reaching the Grail, why bother looking for it at all?

13. So, which is it, tubes or SS?
Definitely SS -- yeah, buddy! I could spend thousands of $$ for a few "old timey" watts that may sound good, but that just doesn't make good sense to me. That said, however, there are some guys out there that have a good approach to tubes, use SS for the bottom region where it does the best and use tubes for the top end where they shine. If I were to find a good tube outfit that I could afford to blow money on, I would definitely give them a try But most of the time they are more time, money and trouble than what I am willing to go through.

14. What does the future hold for speaker design?
I don't really know for sure. I would hope that there is a day when we can use the entire wall as an active speaker system. Just watch an episode of Star Trek the Next Generation, they have lifelike reproduction of major musical pieces that follow every subtle nuance of the live event and you don't ever even see a speaker grille anywhere. That is cool. It would make the wives of the world happy, too.

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Copyright: Peter J. Smith 2005 Return to helarc.com