kenratboy Posted February 16, 2006 Share Posted February 16, 2006 The picture on the left is of a speaker with one driver firing stright foward, with the one above and below firing UP a little, and DOWN a little, respectivly, say 15-degrees. The picture on the right is the same, but the middle driver is still firing foward - but the top is firing to the left, and the bottom one to the right. This is just something I am doing 'in theory' with 3-4" full range drivers. In my mind, I am having trouble deciding which one would work best for stereo speakers (as part of a HT system). This is NOT about perfect, precise sound, but wide dispersion and making it a little 'fun' I am leaning towards the right side - as the sound is on the same plane, but allows for a wider sound stage and would accomodate less than ideal placement and seating positions. The center would be the left speaker turned 90-degrees. Or, if you HAD to use 3, 3-4" full range drivers for a R/L speakers, how would they best be configured (but not all on the same flat baffle). Thanks! YOU MUST CLICK ON THE PICTURE - or else you cannot really see it. Only 180k. Quote Link to comment Share on other sites More sharing options...
ben. Posted February 16, 2006 Share Posted February 16, 2006 Ehhh... You want fun & dispersion of your choice? Use a horn, man! Truth be told, the polar response of either of those options will be unpredictable, but I think you're on the right track for a quick and rough DIY thing. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 16, 2006 Author Share Posted February 16, 2006 I'm working on a little project idea with someone, and trying to figure out some fundamental designs for full-range speakers. Honestly, kinda a.........B0S3........parallel - but I just want to play with it a bit and see what happens. Unless I get a CNC machine and ABS injection mold, this would be impossible to DIY - oh, and a staff of electrical and acoustic engineers for the needed work. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 16, 2006 Share Posted February 16, 2006 Sounds like you need to do some reading up on transmission line theory... What nominal dispersion angles are you trying to achieve? Gotta start with the goals first before trying to do anything [] Btw, my vote would be for all drivers mounted as close as possible to each other all facing the exact same direction - there are certain advantages to plane wave sources, which you would be moving towards with such an arrangement. Oh, and building horns out of wood is really easy - and it only takes about a week of reading and some skills in excel to come up with some plans of your own... Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted February 16, 2006 Share Posted February 16, 2006 You're trying to design a side surround cabinet here, is that right? I'd vote for the right most design then. The two angled drivers with spread out the horizontal disperson of the three identical drivers. Those two will have the added benefit of splashing some sound waves against the nearby wall, increasing the apparent soundstage. It's really not much more than the WDST design of the RS series, but in a line configuration. You could probably dump the center speaker without much detriment in dispersion pattern, in fact by decreasing the amount of direct sound, you'd further spread out the sound field. Michael Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 16, 2006 Author Share Posted February 16, 2006 No, right and left speakers. Again, the point is I am NOT trying to make the 'best' speakers, or else I would not be using full-range drivers in a small, molded-plastic box! I am trying for a specific idea, and within that idea (think like you are in MARKETING for a second, NOT engineering!), which solution would work best or be the best 'gimmick' Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 16, 2006 Share Posted February 16, 2006 I am trying for a specific idea... Well what is the idea you're trying to achieve? Just A or B? I don't see the point unless you're trying to learn something in the process... Quote Link to comment Share on other sites More sharing options...
filmboydoug Posted February 16, 2006 Share Posted February 16, 2006 I'd keep them flat. Some tall arrays are concave to try to keep all the drivers at the same distance to the listening position. With three drivers this would not be necessary but would sound better than those two options. The bigger worry is the driver size. Assuming a driver center to center distance of 4.25" you are going to have comb filtering issues above 3390 Hz. Dr. Jim Griffin's Line Array white paper is available here. http://www.audiodiycentral.com/awpapers.shtml Quote Link to comment Share on other sites More sharing options...
filmboydoug Posted February 16, 2006 Share Posted February 16, 2006 I just reread your post. I think the left option would for sure look nicer. [] No, right and left speakers. Again, the point is I am NOT trying to make the 'best' speakers, or else I would not be using full-range drivers in a small, molded-plastic box! I am trying for a specific idea, and within that idea (think like you are in MARKETING for a second, NOT engineering!), which solution would work best or be the best 'gimmick' Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted February 16, 2006 Share Posted February 16, 2006 then make it a triangle with one speaker bouncing off the wall for 'wrap around sound' Then you're working on the Bose principle. Ok, I'm with WHo on this one now. Transmission line is different. Why splay the drivers out for L/R? But if you're just experimenting, build one of each and give it a listen. Wood is cheap. Heck, I tried something like this with small 'full range' speakers and PVC pipe sections one time, just for fun. Michael Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 16, 2006 Author Share Posted February 16, 2006 then make it a triangle with one speaker bouncing off the wall for 'wrap around sound' Then you're working on the Bose principle. Ok, I'm with WHo on this one now. Transmission line is different. Why splay the drivers out for L/R? But if you're just experimenting, build one of each and give it a listen. Wood is cheap. Heck, I tried something like this with small 'full range' speakers and PVC pipe sections one time, just for fun. Michael Why splay the drivers? Back to my original post... A GIMMICK!!! Quote Link to comment Share on other sites More sharing options...
djk Posted February 17, 2006 Share Posted February 17, 2006 For three drivers: face the top one down a bit, the middle one straight ahead, and the bottom one up a bit(concave array). This will reduce comb filtering in the vertical plane, and act like a point source (single driver) from the focal point outwards. Broad horizontal dispersion. The Klipsch MCM 1900 5-tweeter array is an example of this, they sound fine. For four drivers you have two choices: similar to above, or the Bose 402 way (ignoring price, one of the better products they make). The vertical response will be better for up-close listening vs concave, and the comb-filter dips will be steered above and below the listening axis. Quote Link to comment Share on other sites More sharing options...
hwatkins Posted February 17, 2006 Share Posted February 17, 2006 My vote is with djk in theory, but I think you would want to measure and see which way the baffle should angle for the outside cones. I had a similar situation with a center and low and behold angling the outside speakers toward the center slightly provided the best results for off axis listening. 2 cents Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted February 17, 2006 Share Posted February 17, 2006 I read somewhere the fabled Wilson Audio X2 and X1 does a similiar to the first one but instead of the top driveer facing up it faced down, and the bottom one faced up also. This was done for I believe transient response. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 17, 2006 Author Share Posted February 17, 2006 Cool, now we am on to something! If you look at those 402's - those are the general idea, but the drivers would be MUCH, MUCH better (like the 4" Tang Band Bamboo drivers, they are clean up to ~20 KHz.) and they would be for home use. Again, this is something I am playing around thing. The only issue is impedance. All these drivers are 8 ohms, anyway I can hook them up to make them NOT 2 ohms? Could I do 2 together for 4 ohms, and then 1 by itself as 8 ohms, and put them together to get back to ~6 ohms? Quote Link to comment Share on other sites More sharing options...
djk Posted February 18, 2006 Share Posted February 18, 2006 I recommend you do four drivers like the Bose. Wire them in series-parallel for an 8 ohm load. Wire the inner pair in parallel, and the outer pair in parallel, then wire the bunch in series. Connect a high quality capacitor in parallel with the outer pair. This will eliminate comb-filtering at higher frequencies and reduce high frequency reflections off the ceiling and floor. It will also bring up the high end on-axis to keep up with the mutual coupling at low frequency that begins to drop off at higher frequencies. Try different cap values and see what works best, start with about 6.8µF and go up and down from there. Power handling will be roughly 4X that of a single driver, impedance will be 8 ohms dropping a bit at higher frequencies (due to the added cap, but not as much as you would think as the impedance will also be rising due to voice coil inductance). Efficiency will be about +6dB vs a single driver. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 18, 2006 Author Share Posted February 18, 2006 So the idea would be the inner-two drivers would be 'full range' and the outer two would be limited on the highs, to reduce comb-filtering and unwanted reflections? How noticable would comb filtering be? How does it manifest itself? Quote Link to comment Share on other sites More sharing options...
hwatkins Posted February 19, 2006 Share Posted February 19, 2006 One of the resident experts should talk about Comb stuff, but I will give it the first go. What happens here is that the same signal is in some way delayed (electronically, distance from source to ear, yada, yada) and the end effect is something akin to phase cancellation. From what I have heard and modeled the real world effect can range from an accentuation in the Low freqs to a cancellation in the high freqs. I think that is what happened in my center channel project and required me to angle the two outside mid woofs toward the middle - a counter intuitive option. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 19, 2006 Author Share Posted February 19, 2006 Actually, a smaller version of the Bose 502's is the right idea. The drivers are all firing in a different direction to give a wide, reflective soundfield (albeit, not precise and all that, but thats NOT the point of this!!!) Here: This is exactly what I am thinking of. Again, this is a 'special' project I am playing with, I am not going to trade in my Chorus II's or anything. I am just trying something. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted February 19, 2006 Author Share Posted February 19, 2006 Oh, and if you think I am crazy, maybe Dr. Amar Bose stole my account and is posting [] Quote Link to comment Share on other sites More sharing options...
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