need plans for a good line array |
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hansol3
Registered User Joined: 03 September 2007 Location: Canada Status: Offline Points: 1 |
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Hi
I need a plan for a array sytem 10 ,12 or 15 inch and horn 2 ways or 3 ways
tank's
Hansol3
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adambomb
Old Croc Joined: 10 April 2006 Location: United Kingdom Status: Offline Points: 3220 |
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every time I see that avitar I think of toxic.
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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lol |
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me so horny me love you long throw
horn loaded for her pleasure |
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mykey
Old Croc Joined: 18 August 2005 Location: UK/Indonesia Status: Offline Points: 9680 |
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Every time I see yours, I wanna cupa tea.
Edited by mykey - 04 September 2007 at 5:14am |
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NITROSSUB
New Member Joined: 07 March 2010 Status: Offline Points: 2 |
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or any one who is interested i am currently working on a proto type full size line array
quick vids so far using LF 2 X 15" MF 4 X 8" HF 2 X 1.4 http://www.youtube.com/watch?v=rb8I8qMhB20 http://www.youtube.com/watch?v=4xMX67budi8 http://www.youtube.com/watch?v=zFnbY0f2998 |
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SebP
Registered User Joined: 02 February 2010 Status: Offline Points: 127 |
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this waveguide in youtube video can't work as a line source. It's a simple guide: nothing special !!!
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staiper
Registered User Joined: 26 February 2004 Location: Croatia Status: Offline Points: 545 |
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This waveguide (from youtube links) CAN work as "line source" according to Frensel (WST criteria from L'acoustics) as long as wave front curvature is less than 1/2 wave length at highest freq. we want to reproduce. (in later documents they note 1/4 wave length as that ideal curvature) At 16kHz it is ~10.75mm -1/2wl (or ~5.37mm -1/4wl) Slot in youtube video seems a bit shorter and higher than ideal so WST "curvature criteria" will be satisfied only at a bit lower freq. than "aimed" 16-18kHz. ..Yes that is simple diffraction slot and may work full OK as "line source" (but big companies have developed other complicated/very "special" (and maybe only marginally better) ways to flatten wavefront and wrapped all with shiny marketing paper signed by R&D) Edited by staiper - 07 March 2010 at 10:58pm |
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Just do it! ..or do not.. ;)
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SebP
Registered User Joined: 02 February 2010 Status: Offline Points: 127 |
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It's not simply marketing. If you want to produce a cylindrical wave (as opposite to spherical wave), the paths lenghts of the waves must be equal (as much as possible).
With the waveguide in the video, the path of the wave are shorter in the mid of the waveguide than the extrimities. And with this design, you have at least 3 cm path lenght difference, so it can't works as a line source no more higher than 3KHz. Edited by SebP - 08 March 2010 at 8:05am |
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staiper
Registered User Joined: 26 February 2004 Location: Croatia Status: Offline Points: 545 |
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I do not know dimensions of slots in video but if we take those are
roughly ~25cm deep and ~19.5cm height it will give front difference
(curvature) of 18-19mm which will satisfy full ideal up to ~4600Hz
(nearfield conditions - 1/4wl max difference satisfied) and up to ~9200
(far field conditions -max 1/2wl diff. satisfied)
This is not perfect but for most PA situations if setup is correct this may work fine as linearray HF. (..considering that MF and LF unit distances and crossover points are set correctly in respect to "line array" rules/acoustic physics ) Better situation will be if he have used 3 HF slots in same space so every slot will be ~13cm height and than wavefront curvature will be ~8 mm which will satisfy fully up to ~11kHz (~22kHz theoretical in far field -not optimal) which is more than enough for any real world situation for such simple to make device. More critical range with line arrays is MF drivers placement and setup (human vocal range .. where ears are far less forgiving at phase and time imperfections) |
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Just do it! ..or do not.. ;)
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MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7816 |
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SebP,
that is theoretically true. But having 2-3 cm of path length difference only maters if your ear is close to the source. having in mind that this is not how you use a line array box , which means you are at least 6-10 meters away from the source that imperfections smooths out with distance. Aahhh... I should have patented that wave guide :-) |
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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Centauri
Old Croc Joined: 29 November 2004 Location: Newcastle Aus Status: Offline Points: 1792 |
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And maybe I should have done too ......
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SebP
Registered User Joined: 02 February 2010 Status: Offline Points: 127 |
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No, the path lenght is very important for a line source. If you want to
produce a front plane wave, the path lenght must be the same, especially
at high frequencies (because of the short wavelength) Attenuation on a real
line source is in theory 3 dB each time the distance double (6 dB for a
spherical source). Ruban tweeters have this caracteritic, this is why
some companies use them.
So call the video waveguide "line array" if you want, but it will not work as a line source at high frequencies. |
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