The Guru speaks: Richard Modafferi

Speaker Designer Questions

Biography: Richard Modafferi received his B.S.E.E. degree from Manhattan College in 1960 and his M.S. E. E. in 1965 and M.S. Computer Science in 1968 from New Jersey Institute of Technology. Richard worked for Blonder-Tongue Laboratory from 1960 to 1966 designing VHF and UHF television equipment. From 1968 to 1974 he did FM tuner design for McIntosh Laboratories including the MR-78. He has been an independent inventor-consultant since 1974. His 'Infinite-Slope' loudspeaker inventions are licensed to Joseph Audio of Melville, N.Y. His hobbies include vigorous exercise (X-C skiing, running, cycling), vegetarian cooking, and playing piano.

1. Without giving the standard 'weakest-link' answer, how important would you rate speakers as component?
Transducers, i.e., devices converting one kind of energy to another are more difficult to design than devices which operate in one energy domain such as amplifiers, etc., which operate solely on electrical signals. Tuners, phono cartridges, CD players and loudspeakers operate in more than one one energy domain, i.e., converting one kind of energy to another; speakers for example convert electrical signals to acoustic energy (sound). Stated differently, having done all (except digital) I have found the most design challenges at 'ends' of a HI-FI system; tuners, speakers, than the 'middle'; preamps, power amps.

2. How have speakers changed in the past 25 years?
The best have become incrementally better as well as more expensive. The worst have gotten really bad. In the 1950's any decent 5-tube table radio had tolerable sound. Compare this with some of what you find in Circuit City today!

3. Do we have to spend a lot on woofers and tweeters to get good sound?
Usually, yes. You generally get what you pay for.

4. What are the top 3 design parameters you use, or, what do you worry about most?
(1) Uniform sound pressure in entire listening space over as much of the frequency range as possible,
(2) low non-linear distortion,
(3) reliability/simplicity.

5. Do you design on measurement or sound?
Neither to start. Every concept is first modeled in computer using LEAP, etc. After a model works in computer, I build it and test it by measurements. If it measures bad, design is discarded and return to computer if no obvious easy way to fix it. If it measures OK then extended listening tests in field are done. Listen tests reveal any bad things in design and these are fixed if possible. If not, design is discarded again and I start over.

6. What is the special something which makes some speakers sound good?
Correct design, preferably violating no laws of physics!

7. What are your speaker audition strong points and weak points, i.e., what problems do you find it most difficult to pick up in listening tests?
Resonant colorations. Sometimes these are impossible to fix resulting in discard of design. Carelessly-done point-source measurements often do not find this problem.

8. Do you have a theory on crossovers or use whatever seems to work?
Yes to first part of question. See my patents on Infinite Slope filters.

9. Do we overstress the bottom octave and area above 20Khz?
I don't think so. Common sense prevails.

10. What one piece of advice would you give any new speaker builder?
Get a good education. Master's level or better in fields of electrical engineering, circuit theory, acoustics, computer science. Some physics and chemistry would help. Maybe even theology and philosophy. Either formally in college or elsewhere. Fifty years or more of experience could be useful. I'm 67 and began when I was about seven years old.

11. When you are cornered at a party by a speaker builder what is the question they ask most often?
Do you use elliptic filters? No!

12. Will we ever find the 'Holy Grail' in sound reproduction?
I hope not. My best sound is our season-ticket seats at the symphony.

13. So, which is it, tubes or SS?
Anything goes if it's done right, even mashed potatoes! I use tube equipment of my own design; I like the glow of tubes!

14: What does the future hold for speaker design?
I don't know. If anyone says they do know, take it with a grain of salt.

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