rockbobmel Posted February 8, 2006 Share Posted February 8, 2006 I'm glad I'm not that smart.! Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 8, 2006 Share Posted February 8, 2006 The passive cone on a baffle mount is not "tuned" for a specific frequency as a port would be. It is simply a phase inverting mechanism and is physically coupled by and to the volume of air in the back chamber which undergoes compression and rarification as the active cone moves back and forth. Actually, it's not a phase inverting mechanism and the cone excursion of the active driver is still "zero" at the tuning point of the system. Go look at some phase response measurements....they are identical between ports and PR's of the same tuning. Btw, the reason I didn't bust out all the fancy equations is because a) they are ideal world low level linear assumptions which aren't the case in real life. Nobody here would understand them anyway, which c) runs the risk of misinterpretation. d) It would be a complete waste of my time, especially considering that application of the formulas by me doesn't prove anything anyway. e) There just aren't enough letters on the keyboard to draw all the fancy symbols. Everything you just said in that last post contradicts everything they teach in acoustics....you might as well argue that 1+1=3. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 8, 2006 Share Posted February 8, 2006 It wouldn't matter if you did, you'd still be wrong. There is 70 years of loudspeaker history written by some very smart people that you are ignoring. I'll attribute that to the hubris of youth. The facts are that a drone cone is a wider bandpass mechanism than a port. However ports can be LOUDER at their tuned frequency than a drone. DM Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 8, 2006 Share Posted February 8, 2006 I refuse to partake in an ego war and I take great offense to your referencing my age as it has no bearing on the subject. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 8, 2006 Share Posted February 8, 2006 Btw, I just wanted to point out one thing: The pic came from here: http://www.diysubwoofers.org/prd/ and there is this footnote at the bottom: My thanks to Tom Danley and Deon Bearden of the DIY Loudspeakers Mailing List for providing these guidelines for designing Passive Radiators systems. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 8, 2006 Share Posted February 8, 2006 The Drone-Cone, Phase-Inverter Loudspeaker JAES Volume 21 Number 7 pp. 582, 583; September 1973 Author: Olson, Harry F. E-library Location: (CD aes3) /jrnl6877/1973/7206.pdfI would prefer to take this guy's published work as a definitive reference.The man's work was and still is highly respected in the professional scientific audio community. His credentials are beyond reproach. Not that I think Tom Danley is a slouch, but I'm currently unaware of his scientific publishings.DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 9, 2006 Share Posted February 9, 2006 "I refuse to partake in an ego war and I take great offense to your referencing my age as it has no bearing on the subject." This ain't about ego - I'm just backing up everything I said above with references so I have some credibility... **** any patent since 1935 concerning a passive radiator will have been referenced to this one. Harry F. Olson had over 50 years of experience with the passive radiator between this patent and the above AES published paper posted above. DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 9, 2006 Share Posted February 9, 2006 Like this one, for example. This one is a "variable" drone cone with adjustable mass, so that it can be "tuned" for a particular room placement. There is a screw dead center used to fasten a weight to the cone! When you look it up, please note frequency response curves... DM Quote Link to comment Share on other sites More sharing options...
homemadeheresy Posted February 14, 2006 Share Posted February 14, 2006 All I can add to this debate is that I added PRs to my self-fabricated Heresys and the depth and volume of the bass increased dramatically. Now to address the original question: placement is of upmost importance. I have mine in an unfinished (for the time being) basement. The sides are approximately 14 inches from the side(block) walls, and placed about 12inches from the back wall. My sweet spot is 15.5 feet from the rear walls. They throw the bass rather nicely throughout the basement, and the rest of the house for those not wanting to listen to my selection of music while watching tv upstairs[W] . So attempt to work with placement. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted February 15, 2006 Share Posted February 15, 2006 hyperbole- I had one of those once, had it taken out. M Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 15, 2006 Share Posted February 15, 2006 All I can add to this debate is that I added PRs to my self-fabricated Heresys and the depth and volume of the bass increased dramatically. Just outta curiosity...did you go with the stock heresy dimensions too? What you describe sounds a lot like the old Tangent 500 and 400 speakers: http://www.klipsch.com/product/product.aspx?cid=155&s=specs http://www.klipsch.com/product/product.aspx?cid=156&s=specs (500 = PR, 400 = port, both are using the same drivers as the heresy II) Quote Link to comment Share on other sites More sharing options...
Def Leper Posted February 15, 2006 Share Posted February 15, 2006 It sounds like more science than sound. Sound is science, except to audiophiles. For them, sound is money. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 15, 2006 Share Posted February 15, 2006 It sounds like more science than sound. Sound is science, except to audiophiles. For them, sound is money. great analogy [] Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 15, 2006 Share Posted February 15, 2006 Reading the print out values of a machine measuring some reductionistic mathematical derivation of the sound isn't quite the same thing as appreciating a Carlos Santana guitar solo, is it? You could test the frequency and SPL of course, but what will that tell you about the solo in human terms? Point is, audio is both ART and SCIENCE, inseparable from each other, and possibly more of an art than science exactly because a human being is required as the justifying means to the whole affair. Without the human listener, ALL speakers, regardless of cost or quality are just making noise. DM Quote Link to comment Share on other sites More sharing options...
Petrol Posted February 15, 2006 Share Posted February 15, 2006 the four polk monitors that I use in my "mens-club-home-theatre" (small h on purpose, lol) have passive radiators as does my old Klipsch SW-10... the system Rocks the small room with plenty of bass... for my ear at least. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 15, 2006 Share Posted February 15, 2006 Reading the print out values of a machine measuring some reductionistic mathematical derivation of the sound isn't quite the same thing as appreciating a Carlos Santana guitar solo, is it? You could test the frequency and SPL of course, but what will that tell you about the solo in human terms? Point is, audio is both ART and SCIENCE, inseparable from each other... I would argue that you are mixing the concepts of sound and music....sound is merely the medium in which music exists. Music cannot exist without sound, but sound can exist without music. But the better one understands the medium, the easier it is for that person to express the art. (It's like a painter going to school to learn about different paints and brush techniques). After taking some acoustics courses it is quickly apparent that the study of sound has absolutely nothing to do with music specifically and in fact the majority of the research is used in many other applications (acoustical medicience, material science, etc etc...). But this is why good "sound guys" are so hard to come by....they must have a firm understanding of the technical nature AND an artistic ear. You cannot have just art alone. There is a reason for the stereotype that musicians are no good behind the mixer...And I would argue that the same is true for the design of any kind of music equipment, especially speakers. The designer needs to use both sides of his brain. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted February 15, 2006 Share Posted February 15, 2006 Soundwaves without a human ear (and brain) to interpret it is just noise. If a tree falls in the forest... DM Quote Link to comment Share on other sites More sharing options...
homemadeheresy Posted February 15, 2006 Share Posted February 15, 2006 My dimensions are slightly larger than the Heresy III. 24.5"h x 15.5"w x 14"d. I know the Heresy family low end quits around 50 hz, so with the suggestion of a PR from the gentleman I bought my mids from, thought that I would give it a try. After first experimenting with the passive bolted to a piece of material I'd rather not mention, the difference was quite noticeable. Then it was time to cut a hole in the walnut rear and screw the PR into its final resting place. Don't have a decibel meter yet but when I snag one I'll post some results to where the bottom end ends Quote Link to comment Share on other sites More sharing options...
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