Members ratthedd Posted January 16, 2004 Members Share Posted January 16, 2004 A couple of Ford's middle designs reminded me of a horn subwoofer project I had seen somewhere else. I think these designs could be adapted to an array by modifying the "V" at the back of the box so that the HF drivers get loaded in the sharp angle facing straight out. The MF drivers could either be loaded on the outer flare of the horn or somewhere closer to the horn throat: I'm at home without my drawing software so you'll have to try to imagine what I'm talking about based on the following pictures: There's another folded sub-horn I've seen a design for which uses only one chamber for the sub driver and splits into two paths. That one may be a bit more problematic to incorporate the MF and HF drivers into. I'll see if I can find the design and post it here. It may spark some additional design ideas. This program may be of use in determining horn design: http://www.users.bigpond.com/dmcbean/ Link to comment Share on other sites More sharing options...
Members Ford Audio Serv Posted January 16, 2004 Members Share Posted January 16, 2004 I love the input all of you have given so far! It Link to comment Share on other sites More sharing options...
Members Jeremy Bridge Posted January 16, 2004 Members Share Posted January 16, 2004 Two things I can think of. #1 How are you going to change/install the subs? #2 What about being able to put a grill on the front? Link to comment Share on other sites More sharing options...
Members madjack Posted January 16, 2004 Members Share Posted January 16, 2004 Changing the sub speakers should be no problem, just use an axcess port on the top or bottom, much like peavey did with the sp-1 cab. As for grilles, first of all, why? Second, that should also not be much problem using velcro strips and a screws to put on a grill board. Link to comment Share on other sites More sharing options...
Members Jeremy Bridge Posted January 16, 2004 Members Share Posted January 16, 2004 Because grills look profesional and keep {censored} out of the drivers As well the interior parts will have to be recessed in order to have room for the grill. Also the correct grill with foam backing will improve the weatherability of the enclosure a great deal. Lastley it would probably be the most simple to just have the back wall removable IMO. Link to comment Share on other sites More sharing options...
Members Ford Audio Serv Posted January 18, 2004 Members Share Posted January 18, 2004 Thanks for the input guys Grill; Okay if we set all the stuff on the front about 3/8" and make stand offs on the side of the ports I think we will have it. Access panel; How about a removable top panel, and load the woofers on the other side of it's baffle? Mid high horn; We need to be thinking about this! Maybe we can send Dr. Spock out for some "mind melt's" Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 19, 2004 Author Members Share Posted January 19, 2004 I'm back from NAMM with a few comments! First of all, there's a ton of new L.A. stuff out there. Prices will come down pretty quick by next year. Rigging is getting cheaper and easier too. Band pass on the LA's bottom end... I'm assuming that you are talking about either the 10's or the 12's. The problem I see it the upper end of the useable band pass response being somewhere around 150 Hz, which shifts a lot of power bandwidth to the 6" drivers. Is there enough sensitivity and power handling to accomplish the target SPL goals? Gut feeling says that we will run into driver limits. Gary, Is the weight you calculated including all the wood in the enclosure? Seems a bit light to me... just a guess, but figure 12 lbs for the 10 or 12, 5 lbs for the 6", 6 lbs for each HF driver, 5 lbs for the horn array, and 8 lbs for the grille and input plate = is about 59 lbs without the box. Looks like about 30 lbs of wood, corners and skin (spray on or fur) and I get around 90 lbs (still not bad for a box of this complexity). Is this getting too complicated? A lot of the cpmpact product out there now was front loaded and either 2 way or 3 way. I'm beat... time for bed! Link to comment Share on other sites More sharing options...
Members Redbassman Posted January 21, 2004 Members Share Posted January 21, 2004 Bump, Link to comment Share on other sites More sharing options...
Members kevinnemrava Posted January 21, 2004 Members Share Posted January 21, 2004 after much discussion..... I would like to pose the question directly and specificialyWhat do we want to do for the low end in the box? we can use anything from 8" to 15" --- and horn to direct to sealed - ported- bandpass- some sort of manifold Although I like the iea of a horn, I do not think it will work with our design goals, and experiance we have here. I would like a design that has low distorion , and higher effecency. What are your toughs on the low end of the box? Link to comment Share on other sites More sharing options...
Members Ford Audio Serv Posted January 22, 2004 Members Share Posted January 22, 2004 Originally posted by agedhorse I'm back from NAMM with a few comments! First of all, there's a ton of new L.A. stuff out there. Prices will come down pretty quick by next year. Rigging is getting cheaper and easier too. Band pass on the LA's bottom end... I'm assuming that you are talking about either the 10's or the 12's. The problem I see it the upper end of the useable band pass response being somewhere around 150 Hz, which shifts a lot of power bandwidth to the 6" drivers. Is there enough sensitivity and power handling to accomplish the target SPL goals? Gut feeling says that we will run into driver limits. Gary, Is the weight you calculated including all the wood in the enclosure? Seems a bit light to me... just a guess, but figure 12 lbs for the 10 or 12, 5 lbs for the 6", 6 lbs for each HF driver, 5 lbs for the horn array, and 8 lbs for the grille and input plate = is about 59 lbs without the box. Looks like about 30 lbs of wood, corners and skin (spray on or fur) and I get around 90 lbs (still not bad for a box of this complexity). Is this getting too complicated? A lot of the cpmpact product out there now was front loaded and either 2 way or 3 way. I'm beat... time for bed! Welcome back Andy As you can see we ran a-muck while you were out The band-pass thing came about with the push for horn loading as well did the quad sixes. When I run the power and bandwidth model it looks great they realy come together. 600 watts for low and 400 watts for mid and 150 watts for highs. I hope it will ballance out. (if anything a bit light in the lows) It's a bit heavy but not realey for a box with 8 drivers in it. The power to weight ratio is excellent. 14.3 watts per pound @ 80 Lbs, a KF-650 is 10.3 watts per pound @ 150 Lbs. It has gotten more complex for sure... but it still easy to build ie; no compond angles and such. The horn won't be to bad eather I have been working on that as well. Andy, Take over for me will ya! I have to make a run up north to do a sound job (Elvis) I will be out of the loop for a day or two Keep it rollin guys I will be back. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 22, 2004 Author Members Share Posted January 22, 2004 Is it the Japanese Elvis thing? Link to comment Share on other sites More sharing options...
Members Jeremy Bridge Posted January 22, 2004 Members Share Posted January 22, 2004 Just for information sake a friend of mine did some testing with just two eminence psd 2002's mounted on thier H290 horns. Here is what he wrote me the other day: "Thought you might be interested - I tried two of our H290 horns mounted next to each this morning. I measured in our chamber at 1M from the front of the horns. I checked three spots - mic centered between horns, mic at the center of one of the horns, and half way in between these two points. All looked good - the curves for all three points overlayed each other from 6khz down, and above that, they only deviated by a max of 3dB up to 12k. At about 14k, I got some cancellation in front of one horn - about -4dB. I got a 3dB gain at almost all frequencies compared to one horn, so +6dB when you feed in twice the power." So even with just standard 90x40 horns mounted on top of each other there doesn't seem to be a hugely negative impact. Link to comment Share on other sites More sharing options...
Members Steve_B Posted January 22, 2004 Members Share Posted January 22, 2004 Hello Jeremy, Garry Ford pointed me here after I replied to a thread about slot loaded loudspeakers (which if I remember you also took part in) on the live-audio-board. With regard to the stacked horns you mentioned, have you read the paper on the JBL site Link to comment Share on other sites More sharing options...
Members Jeremy Bridge Posted January 23, 2004 Members Share Posted January 23, 2004 You are so right. I think everyone here should ready this paper. It is very very relavent. http://www.jblpro.com/pub/technote/tn_v1n07.pdf Link to comment Share on other sites More sharing options...
Members Jeremy Bridge Posted January 27, 2004 Members Share Posted January 27, 2004 Everyone read that and get scared or what ? Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 27, 2004 Author Members Share Posted January 27, 2004 It has a lot of good information, and shows that there are several ways to take advantage of combining the acoustic paterns of speakers. There are also lots of ways that it can be a disadvantage too! Link to comment Share on other sites More sharing options...
Members J the D Posted January 28, 2004 Members Share Posted January 28, 2004 Bump Link to comment Share on other sites More sharing options...
Members Ford Audio Serv Posted January 28, 2004 Members Share Posted January 28, 2004 There is a lot of better info here;http://www.l-acoustics-us.com/techsupport/white.html Link to comment Share on other sites More sharing options...
Members Steve_B Posted January 29, 2004 Members Share Posted January 29, 2004 With fireproof flack jacket in position, here are some thoughts about wave guides. Most of the manufacturers make a big thing about sculpting the high frequency wave fronts, but I wonder how much of this is smoke and mirrors. One of the common phrases is isophasic. An isotherm is a line joining points of equal temperature, isobar, lines joining equal pressure. These lines can assume any shape; just look at a weather map. Presumably an isophase is a line joining points of equal phase. From the drawings that accompany the isophasic horns, we are led to believe that it means the device produces a plain wave front rather than a spherical one. The diagrams show a wave front that doesn Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 29, 2004 Author Members Share Posted January 29, 2004 SteveB, I hope you are willing to share that fireproof jacket with some of us here too! Excellent points which surely concur with the emperical findings that I have made using horns of a more traditional geometry. I have been a long time follower of JBL's theory, and there are numerous examples where this is used in practice... namely the Apogee ALA-3 and ALA-5, plus others that you mentioned. But... in order to achieve marketing advantage, you have to present something "revolutionary", and it must look that way too. I think that much of the advantage in sound quality on traditional line arrays (not the actively steered type) is the use of high quality components, excellent basic technology, top notch packaging/rigging, and the physical fact that the cabinets are well placed in a linear array fashon. Just my personal take. Link to comment Share on other sites More sharing options...
Members Steve_B Posted January 29, 2004 Members Share Posted January 29, 2004 With fireproof jackets handed round, As this is a discussion about designing a line array, I think that it is important not to be taken in by the marketing departments Link to comment Share on other sites More sharing options...
Members Ford Audio Serv Posted January 31, 2004 Members Share Posted January 31, 2004 Wow Steve where have you been all my life It's going to take me a bit to digest all that. I would have to say that it's good news that we may not need worry to much about the isophasic thing. Like you say there are a lot of designs out there that don Link to comment Share on other sites More sharing options...
Members Steve_B Posted January 31, 2004 Members Share Posted January 31, 2004 When all is said and done it is what the PA sounds like at the end of the day. That the line arrays from the big manufacturers work seems undisputed. How much of that comes down to fancy high frequency horns I think is debatable. The idea of the flat wave front is that every position along it acts like a point source. If you consider a normal drive unit, the reason it exhibits increased directivity at higher frequencies is because the sound from each little bit of the cone acts like a point source interfering constructively and destructively with the sound from all the other little bits of the cone. The reason that I posted the previous stuff is to try and get people to step back and look at the design overall. Having seen a few pictures on the internet where people have built, or tried to build, line arrays, the results, just from looking at the pictures can Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 31, 2004 Author Members Share Posted January 31, 2004 All combinations of drivers in any type of array will change directivity... even 2-15's, 4-8's and a line of horns. Will it be useable directivity will depend on spacing, the response of the horn ar it reaches the edges of it's pattern, and even the smoothness of the cone drivers as peaky response combined with an unpredictable and peaky polar pattern will produce unacceptable results. What the good performing commercial line arrays have in common are high quality drivers, tight inter-driver spacing and good packaging. What they do not have in common is a consistent mid and high frequency solution.... but they all still sound good. Maybe the super-propriatary hardware is only a part of why they work? Link to comment Share on other sites More sharing options...
Members Steve_B Posted January 31, 2004 Members Share Posted January 31, 2004 I entirely agree that the layout and spacing of drive units in any array will affect the directivity. The point that I was trying to make was that what the main manufacturers have in common is that they have taken the horizontal spacing into consideration as much as the vertical. This is something a lot of amateurs (for want of a better word) overlook. The horizontal spacing is just as critical as the vertical. A big problem with forums like this is not knowing what level of knowledge and theory other participants have. I apologise if any comments seem condescending. It is also sometimes difficult to express in words what a simple drawing would accomplish. That said Link to comment Share on other sites More sharing options...
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