Line Arrays. Are they superior to point source??

[SY]

ROFL! Excellent.

[pinkmouse]

Originally posted by SY
PM, some interesting measurements of the different power laws between point and line sources appear in d'Appolito's book. It's evident from these measurements that mixing lines and points is bound to cause frustration.

I bought that book a few years ago, and a friend borrowed it, and promptly moved to Australia, (Mark, I will find you one day ). I suppose I ought to get round to getting another copy really.

All

I will admit that my experiences are totally subjective, but every domestic line array I have heard has had a very small sweetspot, much more so than conventional TMW setups. However, Jim's paper is once again challenging my ideas, so I can see I have yet another project for the future. Isn't this diy lark fun!!!

[7V]

Originally posted by Ian J
Hey Steve, love your ebay thing - cost effective advertisiing

Sadly I have to report that my company is "considering its position" with regard to the sale of the Kleenex high end audiophile accessory.

Apparently, someone complained to eBay about the auction and they have banned it. Sigh! According to the feedback I was getting, many people found it amusing. I was really looking forward to the next auction in the series as well.

The 'humour police' are very much alive and well and they're living somewhere in the hi-fi community.

For those interested, I believe that Asda, Sainsbury, Tesco, Safeway and Boots (among others) are alternative sources for the product. Whether it works as well as mine .....

[SY]

I will admit that my experiences are totally subjective, but every domestic line array I have heard has had a very small swee

Small sample size (one line source speaker in house) and totally subjective reaction- same as yours. Mine sounds good over a pretty big window, but sounds great in one spot only. One of the Bay Area diyAudio members was over a few weekends ago and commented the same thing.

[Jim Griffin]

I would believe a small sweet spot in a line source if they are electrostatic or perhaps some planar sources. But if the line is an array that is realized with inherently wide dispersion drivers plus if it is operated in its near field, a narrow sweet spot will not be an issue. In fact, the sweet spot will be wide enough that some listeners (who are used to small, head-in-a-vise point sources) will comment on the diffuse nature of the image. Literally, the image of near field line array can approach the entire area between the speakers. With such a near field array the image will be solid and within the sound stage all of the various sound elements will be located in the correct locations.

[SY]

In my particular case, yes, ESLs, but fairly narrow (about 6 inch wide active area). Not as narrow as a lot of ribbons.

[GM]

>I'd draw the line (bad pun) this way: if at the intended listening distance and range of listening heights, the power law is closer to 1/r and the spectral balance is independednt of height, what you've got is a line source.

====

Right, and by default, this means no XOs in the line and with enough discrete elements to create so much comb filtering that our internal audio processor sums its response to the equivalent of a single large point source, a salient point that in recent years seems to have dropped by the wayside when these are discussed. As good as JG's or any other's power tapered arrays may sound, they aren't line arrays, ergo their 'sweet spot'/power response shifts with frequency based on each summed driver's polar response, just like any other WMTMW.

The one true line array I auditioned (McIntosh XR290) had no 'sweet spot' in a typical sized listening room, instead sounding very close to a live event WRT dynamics/transient response, with moving around the room having little affect on its power response and tonal (spectral) balance.

The downside is cost and building complexity since it requires at least a three way vertical array of many appropriately sized drivers.

GM

[SY]

GM: D'accord. There's a lot of stuff out there labeled "line source" that really ain't. I go about 8 feet of active area, no crossover.

I think that the width of the sweet spot will definitely depend on both vertical AND horizontal dispersion. That's one issue I'm looking at for extending the bass and max SPL of my speakers with a line of small mid-woofers.

[Jim Griffin]

GM said:

Right, and by default, this means no XOs in the line and with enough discrete elements to create so much comb filtering that our internal audio processor sums its response to the equivalent of a single large point source, a salient point that in recent years seems to have dropped by the wayside when these are discussed. As good as JG's or any other's power tapered arrays may sound, they aren't line arrays, ergo their 'sweet spot'/power response shifts with frequency based on each summed driver's polar response, just like any other WMTMW.

JG Replies:

If you correctly design a line array, then it does function as a line source (no comb lines) within the parameters for driver spacing and such (see my white paper for the details). My latest efforts use less power tapering than the earlier design that you heard last year so there is less unevenness in the vertical image. The tradeoff with power tapering is how to control sound bloom yet not reduce the vertical image size so much that you just have a point source. My latest efforts are impressive in their ability to create a true line source sound with very stable but wide image plus yield even power responses to both vertical and horizontal ddirections. The crossover is executed where the drivers have very broad horizontal dispersions so the blend is near seemless.

The problem with no crossover discrete driver arrays is that they have even severe compromises on driver spacing which leads to even more restrictive power dispersion in especially the vertical and ultimately even within the horizontal plane.

Bottom line is that my latest array is a true line array and definitely not a WMTMW by any means.


GM Said:

The one true line array I auditioned (McIntosh XR290) had no 'sweet spot' in a typical sized listening room, instead sounding very close to a live event WRT dynamics/transient response, with moving around the room having little affect on its power response and tonal (spectral) balance.

The downside is cost and building complexity since it requires at least a three way vertical array of many appropriately sized drivers.

JG Replies:

You said in your first paragraph that the best way to go was to have no crossover for a true line array yet your example of a true line array is a three way design. The XR290 is an excelllent design but very expensive and complex as you point out. I'll agree that line arrays can best create a live event WRT to dynamics and transient response.


Jim

[Bas Horneman]

I'll agree that line arrays can best create a live event WRT to dynamics and transient response.

Hi..planning a line array as well, hence my interest.

Would it be true to say that the transient response/dynamics (is there a difference?) is due to the number of drivers, rather than the topology?

I have to admit, the closest I ever came to listening to a line array was the Mission 753 (WWWWT)..That sounded very fast! (Apart from ESL's)

Cheers,
Bas