MarkPAman Posted February 5, 2007 Share Posted February 5, 2007 Have a read of Dave Rat's Sound Nerd Speak (starts just after the orange photo) on line arrays. Some of it is a little technical, but Dave writes very well. (I understand it anyway!) <_< Edit - been thinking about andyc's post and I dont think it's right. Link to comment Share on other sites More sharing options...
Peter F Posted February 5, 2007 Share Posted February 5, 2007 been thinking about andyc's post and I dont think it's right. Neither do I. It's from the picture onwards that I think it swerves from the path of fact. I am sure someone who is much better at explaining these things will be along shortly to correct either you, me or Andy. Cheers,Peter Link to comment Share on other sites More sharing options...
Bobbsy Posted February 5, 2007 Share Posted February 5, 2007 I've been a great fan of Dave Rat's tour blog and have posted links to it before. His comments on line arrays are very valid because he's designed and sold non-line array systems...and is also a v-DOSC dealer...so if anyone is in a position to compare them, it's Mr. Rat. As for andyc's drawing, what it suffers from is over-simplification. The biggest issue is that the coverage of the individual speaker boxes varies with the frequency...and line array manufacturers have to jump through hoops to alternately use or simply get around these variations. The most important part of Dave Rat's article is where he explains that ALL sound systems involve compromise. There are times when a good line array will be the best compromise...and times when it won't be. Bob Link to comment Share on other sites More sharing options...
andyc Posted February 5, 2007 Share Posted February 5, 2007 Which bit do you not think is correct? This is the simpelest possible explanation I could come up with, delve any deeper into the actual physics of these systems and you begin to get too bogged down with the science. Andy Link to comment Share on other sites More sharing options...
Seano Posted February 5, 2007 Share Posted February 5, 2007 As for andyc's drawing, what it suffers from is over-simplification. I'm not so sure, I think the error is more conceptual. Andy's picture treats the line-array as what Dave Rat describes as a 'zonal' system - each speaker doing its own thing with minimal interaction between them. This isn't actually the case, its a 'summed' system. In case anyone missed it, that Meyer link you posted earlier is worth mentioning again. He's not quite right about the telehandler forks either, they're rectangular in cross section and have a radius of curvature at the corners of the order of a millimeter or two when new, and can develop a sharper edge and/or burrs with wear. 'Quite a radius' would be a better description of the structural tube immediately behind the tines, which is circular and has a radius of somewhere around 10cm. Seanx Link to comment Share on other sites More sharing options...
paulears Posted February 5, 2007 Share Posted February 5, 2007 Andy's drawing I suspect is what muddied the waters. We've already had the theory explained a bit, but in Andy's drawing the 'beams' don't overlap, and it's the product of the overlapping that gives the majority of the reduced height, compared with width that line arrays are so good at. Without any background, you'd be forgiven for thinking that the idea of a LA is just to provide zoning. The dispersion can be well predicted with computer software and small tweaks to angles can make coverage even. It would be a mistake, though, to assume that each box is considered individually, when each one is 'just a small part of the 'whole'. Link to comment Share on other sites More sharing options...
Bobbsy Posted February 5, 2007 Share Posted February 5, 2007 Nicely put, Paul. I'm afraid that line arrays are one of those areas where even the "dribbling idiot" version has to delve somewhat into the physics or the explanation just won't be correct. Bob Link to comment Share on other sites More sharing options...
MarkPAman Posted February 5, 2007 Share Posted February 5, 2007 Edit - been thinking about andyc's post and I dont think it's right. Sorry to post & run, but it’s a little busy here for a change! The problem was the lack of overlap and that no mention is made of close coupling so that the speakers act as one. I was putting a longer post together, but have been beaten by Sean, Paul, & Bob. Link to comment Share on other sites More sharing options...
SteveB Posted February 6, 2007 Share Posted February 6, 2007 It is interesting that the main detraction from Line Arrays comes from companies that don't have them in their product range i.e. Turbo and Funktion One. Mind you I should admit that F1 and me aren't very sonically compatible anyway. I would suggest anyone who is looking for some more advanced reasoning should read Bob McCarthy's Sound Systems: Design and Optimization. In that he makes the case for both the Point Source and the Line Source array and explains how a true line array does not exist at all frequencies. The nature of what is used is more of a switch from the horizontal array to the vertical, shifting the plane of comb filtering to a perspective we are less sensitive. It's well worth the read anyway. Regards Chris Chris, How advanced is advanced? I still remember a little of the maths I learned and have a reasonable understanding of loudspeaker systems (some of my ramblings can be found on my web site www.burton-manor.co.uk ) and wondered whether this book was worth buying. Given I already own several text books on acoustics, including Beranek and Olson, as well as numerous AES reprints, do you think that this would be a beneficial addition? Is the system optimisation specific to a single software package (SIM, Smaart) or does it take a more general approach? Amazon have a copy listed at £27.15 which is less than I paid for Beranek’s Acoustics back in 1978 so I might just go for it anyway. Steve. Link to comment Share on other sites More sharing options...
Chris Hinds Posted February 7, 2007 Share Posted February 7, 2007 How advanced is advanced? I still remember a little of the maths I learned and have a reasonable understanding of loudspeaker systems (some of my ramblings can be found on my web site www.burton-manor.co.uk ) and wondered whether this book was worth buying. Given I already own several text books on acoustics, including Beranek and Olson, as well as numerous AES reprints, do you think that this would be a beneficial addition? Is the system optimisation specific to a single software package (SIM, Smaart) or does it take a more general approach? In all honesty, if acoustics is your bag then buy it today, buy it yesterday or the day before if you can. It's easily the single most useful book I've read on acoustics with specific intent to the live system. I haven't read Beranek and Olson, but the McCarthy book is bang up to date and very specific on our purpose. The optimization discusses techniques and packages, not a method to be followed. SIM, SMAART et al all get mentions as do EASE and CLF. It really is a phenominal book. I would say the first time I read it through I laughed a lot (his humour shows), I learned a lot, and I didn't fully understand about 40% of it. Reading it through again that percentage has dropped to maybe 20% overall. It's a very easy read and a great book, the maths is minimal but there if you follow... it's never explicit lists of equations, but a fair amount of mental visualisation is needed to go along to fill in between the diagrams. Regards Chris Link to comment Share on other sites More sharing options...
Simon Lewis Posted February 7, 2007 Share Posted February 7, 2007 I'd second Chris's comments. I have teh original Meyer sound design book - which is very good, but Bob's second attempt (ina true book format, rather than a 'manual' format) is readable, practical and full of the real world measurement information that comes only from years of hanging up speakers and making them sound good. It's not an easy read, but it's certainly informative.... Simon Link to comment Share on other sites More sharing options...
SteveB Posted February 8, 2007 Share Posted February 8, 2007 It's a very easy read and a great book, the maths is minimal but there if you follow... It's not an easy read, but it's certainly informative.... Mmmm…. Guess that clinches it, I’ll have to buy it and make up my own mind. It can’t be worse than the paper “Complex Time Response Measurements Using Time Delay Spectrometry” by D’Antonio and Konnert. Thanks for the info chaps. Steve. Link to comment Share on other sites More sharing options...
Chris Hinds Posted February 8, 2007 Share Posted February 8, 2007 Mmmm…. Guess that clinches it, I’ll have to buy it and make up my own mind. It can’t be worse than the paper “Complex Time Response Measurements Using Time Delay Spectrometry” by D’Antonio and Konnert.Relative versions of easy... I've got a masters in Engineering and Management which probably means some of the maths I kinda didn't notice. It's defs easier to follow than a JBL Line Array paper. Regards Chris Link to comment Share on other sites More sharing options...
andyc Posted February 10, 2007 Share Posted February 10, 2007 Just got back from Birmingham dunno what all the fuss about the snow is!!!OK, just to Un-muddy the waters...In my description, this is how the elements work in principal. But as in any gas based system you cannot move gas (air in this case) without affecting the surrounding particles. Due to the nature of this, mutual coupling occurs creating "what is hoped" to be a uniform wavefront, ALLOT of this is dependant on the set up and operation of the line array system. Adding subs into the equation gets even more complicated as the distance in all three planes from the mid high elements can create some very strange phasing occurrences. This can be overcome by electronically differentiating the phase of the sub elements. In some systems, (d&b have a good technical description) certain elements in the array are completely phase reversed to create a hypercardiod output from the stack, this (in theory) cancels out some of the sound coming from the rear of the speak, throwing less on the wrong direction. I probably dint explain that part well but if you look at the d&b techical data, the drawings speak volumes. (s'cuse the pun) Andy Link to comment Share on other sites More sharing options...
Simon Lewis Posted February 11, 2007 Share Posted February 11, 2007 Andy, Sorry to drag this out, but you are now mixing cardioid bass enclosure theory with line array theory.... The basis of line arrays is that we are trying to emulate an acoustic line source - where by definition the source is long compared to the wavelength - e.g. a busy stretch of motorway approximates to an acoustic line source when measured within a few hundred meters or so. When measured several kilometres away it tend towards a point source. Most of the knack in creating acoustic line sources is to get the high frequency radiators close enough to couple coherently (usually half a wavelength) and if this can't be done, to use some form of either creating a line source to start with (e.g. a ribbon tweeter) or try and emulate one (bounce the sound off a shaped disc that elps make the sound waves "parallel"). Attempts to introduce gaps in the array will affect coupling, but this is necessary because a) the line source will provide too narrow a dispersion at high frequencies and b) the required coverage cannot be easily achieved using a straight hang. I'm sure that you know this stuff, but it doesn't quite come across as clearly in your posts! Simon Link to comment Share on other sites More sharing options...
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