Jay481985 Posted July 10, 2005 Share Posted July 10, 2005 ---------------- huh? Hypotenuse of a rectangle?? Corner has to deal with the mass of the sides?? Three dimensions are L, W, and H??? Arcs and circles gain their strength through their geometry, where the normal force (perpendicular the material's surface) can be transferred symmetrically to the arc's strong axes (in 2 dimensions for a cylinder BTW). I don't think it was the point of the original post though... Rob ---------------- Hypotenuse is the angle of a trianle that is a right triangle (one side is 90 degrees or perpendicular) The hypothenuse is the longest part of a right angle (sum of A (squared) multiply by B (squared) = C (Squared) The corner has the most load since they have the stress (mass) of both sides of the wall. Meaning they deal with force x, and force y. If it is the corner then it must deal with stress x, stress y, stress z. The wall (not near a corner) has to deal with force -x and force x if horizontal, and force -y and force y if vertical. Three dimension incorporate a Length, Width, and Height, thus called L X W X H or called X Y Z "Arcs and circles gain their strength through their geometry, where the normal force (perpendicular the material's surface) can be transferred symmetrically to the arc's strong axes (in 2 dimensions for a cylinder BTW)." What does "can be transferred symmetrically to the arc's strong axes" mean? A sphere and dome or whatever is considered to be a three dimensional circle or arc. What makes the circle so damn strong is it fact that it spreads the force evenly away from the source of the force. Arcs are just as strong since arcs are just pieces of a bigger circle. A box is weaker due to the fact that if the force say is off the exact middle of a wall of the sub. Each corner will recieve slightly different stress due to the distance of the force to the corner. Thus the side closest to the force will take the brunt of the force making that corner much more likely to fail. Given that a sphere has no given point where a force may exert more pressure. But in a cylinder it is an inbetween as the two corners (where the long side meets the hemisphere) have the most force exerted. The strongest shape for any given container is a sphere but in reality a cylinder with hemispheres at both ends are (Think scubadiving tanks or a helium tank at a baloon place) Those gas tanks exert an enormous amount of internal pressure as they I believe are rated to 30000 psi. They usually are measured in pascals or cubic feet per tank at 1 bar (atmosphere). Most are measured in mass as with airplanes. (When filling an airplane or in fact a race car, they load per weight not by gallons) But what is the weakest point in a gas container? The valve to dispense. It is know that if the cylinder were to ever break off usually it becomes a battering ram for anything in it's way. Sorry for the rant guys. Formice as you know with subwoofer making is that everything is a compromise. A sphere is the best shape for rigidity and strength but the fact of building one or the fact you lose volume as compared to a box makes it very unsatisfactory. Quote Link to comment Share on other sites More sharing options...
formica Posted July 10, 2005 Share Posted July 10, 2005 I hope you realise was teasing... but to clarify... ---------------- Hypotenuse is .... triangle .... the longest part of a right angle (sum of A (squared) multiply by B (squared) = C (Squared) ---------------- I know what a hypotenuse is... for triangles. ---------------- The corner has the most load since they have the stress (mass) of both sides of the wall. ---------------- Stress is a force, and mass it a mass... two different things as you know force = mass * acceleration. The centre of the panel receives the largest stresses due to the "moment" but the corners are weak simply due to the joint construction detail. Also note that weight is also a force... and isn't technically the same thing as a mass. The imperial numbering system adds a little confusion by using the word "pounds" or "lbs" to describe both, although the correct way of describing a weight is "pounds force". Metric has no ambiguity (newtons vs grams). ---------------- Three dimension incorporate a Length, Width, and Height, thus called L X W X H or called X Y Z ---------------- Three dimensional forces are usually referred to in their X, Y, and Z axes, while the size of and object are referred to L, W, and H. ---------------- "Arcs and circles gain their strength through their geometry, where the normal force (perpendicular the material's surface) can be transferred symmetrically to the arc's strong axes (in 2 dimensions for a cylinder BTW)." What does "can be transferred symmetrically to the arc's strong axes" mean? ---------------- as you answered later yourself.... ---------------- What makes the circle so damn strong is it fact that it spreads the force evenly away from the source of the force ---------------- That is transferring the force through the axe with the most material... ie: the strongest axes. I can go into much greater detail, but I really didn't want to send the thread off on a tangent. In case you didn't know, I'm a civil / mechanical engineer. Needless to say that a cylinder is inherently more stable a shape than a box and performs well as a subwoofer enclosure (as does a properly braced box). Smile... Rob Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 10, 2005 Share Posted July 10, 2005 good to hear that we have educated people on the forum and not people who say it's better because he/she says so. Well I would say that a cylinder type enclose would need much less material and no bracing. Hence less work. Though it would lose so much more space. Hey formica, since you are an engineer. I was thinking that since a subwoofer is inherit to how much air it can push; in most port applications, I find that they do not stress port flow as much as the box itself or even the air traffic inside a subwoofer. Would it not seem more likely a properly engineered box with directed air flow would make a subwoofer tighter, cleaner, and punchier? I mean most ports are just a pvc tube. What if there were critical air flow management? Say it helped to move x amounts more of air more then that a standard port. Since ports are restricted by the flow, would it not be wrong to assume one can hit deeper and cleaner with a better flowing port? I just remembered this due to a fact that air tends to stick on smooth surfaces. A golf ball has those dimples to counteract the air sticking to the ball. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 10, 2005 Share Posted July 10, 2005 Actually air is a compressible "fluid" and tends to compress at high port velocities ie: small ports. This has the effect of lowering the tuning point of the enclosure. The "tuning point" will actually change at high driver excursions, even with multiple smaller ports. You are correct that a golfball is dimpled to get more distance through less resistance. It cuts down on the boundary layer resistance. The same techniques could be applied to intake and exhaust ports in an engine, yeilding gains in airflow. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 10, 2005 Share Posted July 10, 2005 surprised that no one created a dimpled port or even rifled port so far with all the snakeoil floating around. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 10, 2005 Share Posted July 10, 2005 Polk Audio did just that, built a speaker with a dimpled port. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 11, 2005 Share Posted July 11, 2005 http://www.webct.com/service/ViewContent?contentID=1249577&communityID=858&categoryID=1249537&sIndex=0 The port looks still smooth on the inside but the port seems to be both ways. Inside and out thus limiting the total amount...like you said michael. I wonder still which would move more air per given pressure. A rifled port or a dimpled. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 11, 2005 Share Posted July 11, 2005 I have a theory about airflow, but am reluctant to mention it, in case someone else takes my idea and uses it commercially. Quote Link to comment Share on other sites More sharing options...
Blackmesa Posted July 11, 2005 Share Posted July 11, 2005 ---------------- On 7/9/2005 12:34:04 PM Jay481985 wrote: ---------------- On 7/9/2005 4:33:49 AM bytor33 wrote: If you're comparing boxes to boxes, yes. A tube however would not need as dense of material because it has to endure much less stress than a box because of it's cylindrical design. ---------------- How would it endure less stress, a cylinder? Umm 50 pascals is still 50 pascals in a cylinder tube. The shape is what makes a tube more rigid without more material. Since the radius of a circle is equidistant from the center to the side. A circle's side recieves even pressue. Thus no need for bracing. Since a corner of the box is 1/2 the hypothenus of rectangle (squares are rectangles to) the distance from the center of the box to the midpoint of a side is closer. (A squared times B squared = C squared) Thus the sides need bracing since they are first to recieve pressure (flexing). Also the corners need no bracing since they are theorectically braced by the other side. But since the corner has to deal with the mass of the sides, they are thus weaker. Again they recieve stress in three dimensions. L X W X H but since a circle has no corners it is not weaker. Also that is a short reason why circles are stronger then boxes but that is not it. But simply stated, which holds more volume per give space? A box, since a cylinder volume is pi*r(squared)* height. But a cylinder recieves equal amounts of pressure as with a box but the cylinder recieves equal pressure per surface while a box does not. ---------------- why did i read that....... Jay, If i read something like this agiain, I will beat you up. ;p Quote Link to comment Share on other sites More sharing options...
Blackmesa Posted July 11, 2005 Share Posted July 11, 2005 ---------------- On 7/10/2005 11:06:53 PM Jay481985 wrote: surprised that no one created a dimpled port or even rifled port so far with all the snakeoil floating around. ---------------- b&w has been doing it for a while http://www.bwspeakers.com/index.cfm/fuseaction/products.techfeatures/ObjectID/3A7554F4-4779-11D4-A67F00D0B7473B37 Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 11, 2005 Share Posted July 11, 2005 ---------------- On 7/10/2005 9:48:55 PM michael hurd wrote: Actually air is a compressible "fluid" and tends to compress at high port velocities ie: small ports. ........................ ---------------- Liquids/Fluids do not compress, only gasses. Quote Link to comment Share on other sites More sharing options...
Zealot125 Posted July 11, 2005 Share Posted July 11, 2005 Just out of curiosity, does the RSW-15 offer an equalizer? If not, what is an alternative to achieve a flatter response? Can you add an equalizer? Can/t the equalizer on the amp/reciever help? Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 11, 2005 Share Posted July 11, 2005 No, the RSW-15 does not offer an equalizer. The absolute best method to achieve a flatter response is to start with a room that has ideal proportions, and add appropriate accoustical treatments. You can add an equalizer, but there are side effects. An analog equalizer will cause phase shifts when used to modify the sound. A digital eq does not suffer this, but must first convert the analog signal to a digital one, then convert the modified digital signal back to an analog one. Using an equalizer is a bit of an excersise in futility, as the moment you "eq" a single spot in a room, you have altered the response everywhere else. IE: you can only affect one spot at one time. For these reasons, it is preferable to avoid band-aids and sly marketing, and treat the real problem, the room. Auralex offers a free consultation service, where you fill out a form and fax/mail/e-mail it in, with the room dimentions and furnishings, types of surfaces. http://www.auralex.com/ Quote Link to comment Share on other sites More sharing options...
Zealot125 Posted July 11, 2005 Share Posted July 11, 2005 Facinating, so say I was going to build a room, what would be ideal dimensions for say an some RF-7 fronts and RC-7 center an RSW-15 and various other surrounds. I know this should go in Architectural, but Im afraid noone will answer if I put it there. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 11, 2005 Share Posted July 11, 2005 ---------------- On 7/11/2005 5:09:45 AM Blackmesa wrote: ---------------- On 7/9/2005 12:34:04 PM Jay481985 wrote: ---------------- On 7/9/2005 4:33:49 AM bytor33 wrote: If you're comparing boxes to boxes, yes. A tube however would not need as dense of material because it has to endure much less stress than a box because of it's cylindrical design. ---------------- How would it endure less stress, a cylinder? Umm 50 pascals is still 50 pascals in a cylinder tube. The shape is what makes a tube more rigid without more material. Since the radius of a circle is equidistant from the center to the side. A circle's side recieves even pressue. Thus no need for bracing. Since a corner of the box is 1/2 the hypothenus of rectangle (squares are rectangles to) the distance from the center of the box to the midpoint of a side is closer. (A squared times B squared = C squared) Thus the sides need bracing since they are first to recieve pressure (flexing). Also the corners need no bracing since they are theorectically braced by the other side. But since the corner has to deal with the mass of the sides, they are thus weaker. Again they recieve stress in three dimensions. L X W X H but since a circle has no corners it is not weaker. Also that is a short reason why circles are stronger then boxes but that is not it. But simply stated, which holds more volume per give space? A box, since a cylinder volume is pi*r(squared)* height. But a cylinder recieves equal amounts of pressure as with a box but the cylinder recieves equal pressure per surface while a box does not. ---------------- why did i read that....... Jay, If i read something like this agiain, I will beat you up. ;p ---------------- cause your a loser plus I bet you you read it for the reason to try and disprove me. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 11, 2005 Share Posted July 11, 2005 It is more the room proportions from one dimention compared to the rest, that are applicable here. There is much information to be had in this subject, ideally this would be applicable to new construction and mostly limited to homeowners. This is not to say that you could not modify an existing room by creating a false wall, changing the proportions. As well as obvious benefits in terms of increased number of room modes and smoother response in the low-end, you will have increased the amount of noise isolation, by leaving an airspace between two walls. Quote Link to comment Share on other sites More sharing options...
Kriton Posted July 11, 2005 Author Share Posted July 11, 2005 UH, how exactly did my thread get hi-jacked? I lost it somewhere a long time ago! Now back to my original question, before the dimples and partial pressures and the inherent weaknesses of the square, the divine proportion and corporate intellectual property espionage? Subs, guys, subs...Any other suggestions as to the three (with Velodyne as the pricier fourth)? (See FIRST post). Thanks for staying on track here! K Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 11, 2005 Share Posted July 11, 2005 Klipsch for music, SVS for movies, sunfire for size. The klipsch rsw 15 basically extends the db for you mains. As the Klipsch rsw 15 is best at 32 hertz, right where the rf-7 usuable range is. The rsw 15 will enforce that. The svs will enforce that to some degree but enhance the lower (32 and below , mostly in the 20's) where the rf-7 cannot hit that loud. The Sunfire is smaller then both. As with svs they are big boxes or tubes. The rsw is a big box. The sunfire is smaller for the size but I hear are musical and deep. But more $$$$. Quote Link to comment Share on other sites More sharing options...
Blackmesa Posted July 11, 2005 Share Posted July 11, 2005 Jay, please dont start ****, I was being facetious and you take things too literally. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 11, 2005 Share Posted July 11, 2005 Stay on topic and btw i was in actuality joking. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.