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In Reply to: RE: The Mellow Monster 8 posted by freddyi on February 12, 2017 at 14:26:38
You ask the best questions around here! Sometimes questions seem too difficult to answer, but with loud speakers all roads lead back to Olson where more things seem to have been forgotten than have been learned since the great man passed. Of special interest is Fig.8 and 9 in the patent application, and in particular sections 29 and 31 of these two figures which depicts a secondary air chamber following the beginning of the horn throat. This is accompanied by an analogous electrical circuit diagram along with a description in the text which describes the effect of such a chamber in terms of an analogous acoustical capacitance and inductance filter. And I thought I had invented this in the 90's following some experiments with a closed chamber version of Bruce Edgar's "Edgar Gap" described in Speaker Builder! Luckily I didn't waste any time and money trying to patent it. Also of note is that of the 44 references of the patent in later patents by others, all but two were cited by the examiner! There is no mention in the Mellow Monster article by author Roald Dybvig of Olson or the patent, but the Mellow Monster fairly screams OLSON! My Dad built a pair of Mellow Monsters in the early 60's with some 828 mids and T35's on top. Unlike Paul Joppa I never got to hear my first record The Ballad of Davy Crockett on them, as my Dad had an audiophile turntable which wouldn't play 45RPM singles.
I bet I still have "the ballad of Davy Crockett" somewhere.
Yikes, I am getting old.
That song goes back to about 1956, and I was probably still singing it in 1957 when the last edition of Olson's Acoustical Engineering was published. There were many stories about people lending this book out and never seeing it again. By the 70's it had become hoarded secret knowledge, and people would not admit that they even owned it. It was reprinted in the 90's by Ed Dell's group. I dunno if I have this, maybe I do, maybe I don't. Back in '03 or so I asked Bruce Edgar at one of his talks what he thought about David McBean's Horn-response program. He said that he had built a horn which had a resonance which was not predicted in the sim, but which was easily tuned out by raising the horn up a bit from the floor (coincidently the MM8 is pictured on small legs). He had asked David McBean if something like this could be accounted for in the program, but his answer was that the program lacked the dimensional ability to do this. Some years ago there was a lively debate on this august forum concerning D.B. Keele's vs W.M. Leaches methods for designing horns. It was speculated that Horn-response was modeled on Leach's method, but someone pointed out that Horn-response pre-dated Keele's and Leach's horn papers, and it originally existed in some form in Fortran V in the days of room sized computers! I believe that David McBean himself said that Horn-response was based on Olson's Dynamic Analogies. So as to Freddy's original question of whether Horn-response could do a sim of the MM8, it looks like the answer is no, factoring in the acoustical filters of the several chambers pictured in the patent. Horn-response could sim the rear horn of a back loaded horn design as a strait horn though. I believe that David McBean said here some time ago that a double loaded horn (like the second version in the Olson patent) could also be simed in Horn-response as 2 strait horns, but he didn't see the use of it.
All roads lead to Olson!
Thanks for sharing that.
I got an Applied Physics degree in 1987 and Dr Eugene Patronis (Pataxial - horn within a horn) was my professor, mentor and father figure to me. I knew about Leach (he was in EE department), but never met him.
Since then I've learned much of Harry Olson. He was/is the real deal and the father of modern loudspeaker design
Agreed, doc P is an amazing guy and i am proud to count him as a friend and advisor to the company.
I never met professor Leach but his paper of horn loading was the basis of many of my bass horn designs.
Danley Sound Labs
Patronis was one of my favorite professors also. What a guy!
Do you mean this one? :)
Download CLICK HERE
The earlier Elements Of Acoustical Engineering (AKA Elephants Of Acoustical Engineering In The Room) was also reprinted in paperback several years ago as a Nabu Public Domain Reprint. Just to add to the confusion, an original work published before 1923 (!) is referenced in the publisher preface. This paperback may still be available, and quite a bargain for anyone not willing to pay the $70+ for the 1991 Professional Audio Journals reprint of the 1957 version of Acoustical Engineering with the blue hard cover. In case anyone is still not confused enough, the online link here lists the original edition of Elements Of Acoustical Eng. from 1940, with a 2nd Ed. in 1947, and another 2nd Ed. in 1957 and a reprint in 1960!
Anyway enough complaining, and thanks for the link for all to see. I'm still not admitting that I own any of this stuff due to all the confusion. For some engineering high drama see p. 23 in the link and see the spherical enclosure moping the floor with the various other types tested. I predict that this will again be re-discovered, and remember that you heard it here first that you saw it there first.
there's this 1940 version of "Elements" At The Internet Archive
Thanks for the extra link, and there's also a link from that page to another online copy of Elements at the Biodiversity Library. BTW the 1991 reprint of Ac. Eng. is apparently out of print again and "collectible" as the prices on Amazon reveal: $480-$800! Anyway the most important stuff, including the Horn chapter, is in the Elements version which is in the public domain.
Spot-checking the PDF Table of Contents, this 1960 reprint does agree with my 1957 hardcover. However, the photo of the book's spine at the beginning is wrong. "Elements of Acoustical Engineering" was the earlier work. "Acoustical Engineering" (as shown in the photo which I provided) is the later work.
Audiophiles who wish learn more about the fundamentals, as well as related important areas such as musical instrument characteristics and room acoustics, but don't want to wade through Acoustical Engineering, should get "Music, Physics and Engineering" also by Harry Olson. Last I checked, it was still available in paperback.
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