Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Jim McKeveny]

The understanding of driver critical-distance, the length of those driver lines, and the rendering of consistent "pie-slice" coverage was an epiphany in the 90's.

Now I see widespread ignorance of those physical realities. The marketplace is fogged with name-brand companies offering useful performance from 2x12"/2 x10" + 2x1" elements. Pattern-consistent performance throughout the multi-octave crossover region is not credible on its face, and not fixable with DSP.

[Mark Wilkinson]

The understanding of driver critical-distance, the length of those driver lines, and the rendering of consistent "pie-slice" coverage was an epiphany in the 90's.

Now I see widespread ignorance of those physical realities. The marketplace is fogged with name-brand companies offering useful performance from 2x12"/2 x10" + 2x1" elements. Pattern-consistent performance throughout the multi-octave crossover region is not credible on its face, and not fixable with DSP.

I can't compare what was being discussed about line arrays in the 90's, having only become interested is speaker building in the last 5 years.
Everything I've read though, says the tightness of center-to- center spacing determines how high in frequency the line will behave as a line; and how long the line is,
will determine how low in frequency pattern control is maintained.

That still seems to be universally acknowledged.

What does seem to have changed are the methods to achieve tighter acoustical high frequency c-to-c spacing.
And the use of steeper crossovers to lesson the difficulties of multi-octave summations, along with more precise time control of the individual high-frequency drivers.

I guess from reading, that V-Dosc first used an acoustic lens/waveguide for the c-to-c acoustic tightening / focus. ?
Now it seems like there's a bunch of different methods. 
More smaller drivers on a waveguide. Wavequides with vanes or phase plugs to hopefully split a larger driver into smaller acoustical pieces. Combining multiple drivers with paraline plates,   Virtual acoustic focus via timing offsets. etc etc.

But I think the goal of all of them is to get apparent acoustic c-to-c spacing seamless.....and then be able to cross over to next driver section below, to take the acoustic baton.

It doesn't take much in the way of FIR processing, or latency, to put very steep crossovers in play at that HF to MID hand-off.

My guess is that's where most the engineering comes in apart from minimizing c-to-c. .....
getting the VHF/HF to have enough SPL to keep up with bottom, keep the c-to-c of the different driver sections within 1/4 wavelength at xover freq, and still have pattern blend together.....

So, just a bunch of thoughts wondering how much the physical realities are being ignored, or if maybe they are just being ignored at the price point where having a line array is more important than sound, for a small operator's image .?

Is there a respected touring company's box, like a 2 x 12" or 10's", with a couple of 1" CDs, that you can point out as an example of bad juju? 
No doubt they're out there

[Nick Pires]

The understanding of driver critical-distance, the length of those driver lines, and the rendering of consistent "pie-slice" coverage was an epiphany in the 90's.

Now I see widespread ignorance of those physical realities. The marketplace is fogged with name-brand companies offering useful performance from 2x12"/2 x10" + 2x1" elements. Pattern-consistent performance throughout the multi-octave crossover region is not credible on its face, and not fixable with DSP.

Which line arrays have taken these physical realities into consideration, and which ones haven't?
V-Dosc splayed at the front, increasing C-C distance well beyond what would be required for coherent HF summation. Same was true with Meyer M3D, and EV X-Line.
Also, which brands are employing DSP with multi-octave crossover regions?

I think some designs are better than others at addressing vertical and/or horizontal driver spacing issues, but there are always going to be compromises as long as we rely on magnets.

[Doug Fowler]

Which line arrays have taken these physical realities into consideration, and which ones haven't?
V-Dosc splayed at the front, increasing C-C distance well beyond what would be required for coherent HF summation. Same was true with Meyer M3D, and EV X-Line.
Also, which brands are employing DSP with multi-octave crossover regions?

I think some designs are better than others at addressing vertical and/or horizontal driver spacing issues, but there are always going to be compromises as long as we rely on magnets.

NEXO Geo T used a clever design to prevent "front splay" being required.

[Jim McKeveny]

No V-DOSC "splayed". Christian Heil developed the concept to well below the HF region with smaller-than-contemporary MF cones and and innovative HF (+1k) device. D&B uses a wide-range coaxial MF/HF driver on an optimized waveguide. The VerTec team at JBL (Mark Engebretsen?) brought small-format MF cones to the party. The goal was to integrate/predict the at-distance decay of the lion's share of spectrum.

I will not name "Names", but the blunderbuss/anecdotal/throw enough shit in the air approach has crept back.

[Art Welter]

I will not name "Names", but the blunderbuss/anecdotal/throw enough shit in the air approach has crept back.

Crept back? Never left.

[Don T. Williams]

Art is right about that.  The deployment of a whole lot of "line array" speakers (maybe most) breaks the rules set forth buy Dr. Christian Heil when they have very large "J" curves or fixed angles greater than a very few degrees between cabinets.  Imperfect?  Yes it is.  But it is better than the huge numbers of "point and shoot" cabinets that preceded the development of "line arrays".  A few companies are working on the concept of perfect summation of drivers to create a perfect point source loudspeaker large enough to cover a huge audience, but so far the systems are not scalable and deployable in the same way LA cabinets are.  Keep working guys.  It's getting better!

[Helge A Bentsen]

Have you guys used EAW Adaptive?

[Nick Pires]

No V-DOSC "splayed". Christian Heil developed the concept to well below the HF region with smaller-than-contemporary MF cones and and innovative HF (+1k) device. D&B uses a wide-range coaxial MF/HF driver on an optimized waveguide. The VerTec team at JBL (Mark Engebretsen?) brought small-format MF cones to the party. The goal was to integrate/predict the at-distance decay of the lion's share of spectrum.

I will not name "Names", but the blunderbuss/anecdotal/throw enough shit in the air approach has crept back.

Your initial post and response are vague, which (to me at least) seams to be concealing your point. Every single line array design (or any speaker design for that matter) ever comes with compromises. If you look at a high enough frequency, no line array has ever been able to maintain uniform acoustic center spacing in a long enough array to have broadband vertical pattern control. For a variety of reasons (weight, ergonomics, aesthetics, price point, etc.), there have been products that outright ignore some of the principals that make well-designed line arrays as useful and effective as they can be. But that isn't any different now than 15 years ago. I don't think it has "devalued the line array concept." Some companies are trying to make money by eliminating as many compromises as possible and adhering to the "rules" that make the tool better, other companies are trying to make money by appealing to users who are willing to accept more compromises in exchange for a cheaper, lighter, or smaller product.

[Steve-White]

Your initial post and response are vague, which (to me at least) seams to be concealing your point. Every single line array design (or any speaker design for that matter) ever comes with compromises. If you look at a high enough frequency, no line array has ever been able to maintain uniform acoustic center spacing in a long enough array to have broadband vertical pattern control. For a variety of reasons (weight, ergonomics, aesthetics, price point, etc.), there have been products that outright ignore some of the principals that make well-designed line arrays as useful and effective as they can be. But that isn't any different now than 15 years ago. I don't think it has "devalued the line array concept." Some companies are trying to make money by eliminating as many compromises as possible and adhering to the "rules" that make the tool better, other companies are trying to make money by appealing to users who are willing to accept more compromises in exchange for a cheaper, lighter, or smaller product.

Bingo.  We often loose sight of this.  Any system is a manufactured product, designed not to a standard of audio perfection - but to a business model with marketing and sales in mind as a part of the overall set of decisions and compromises that are made to arrive at the final product configuration.

My employer as a company does that every day in the fighter jet business, it's basically performance -vs- weight/strength -vs- fuel economy, which translates to operational range.  A bit more complex than that - maintenance hour to flight hour (MH/FH), mean time between maintenance or failure (MTBM MTBF) and such.

A balancing act of factors.  Every manufacture of every product does or should do this.  Market research and so on.  That's where I like to head off into the DIY world, where it's more about the design and performance, pure innovation and less about business case supporting manufacture.  Much easier to make changes to small run DIY that to release engineering and retool a production line or change parts from suppliers that end on in the final assembly.

[ProSoundWeb Community]