Line Arrays. Are they superior to point source??

[Brett]

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

No, that would go to horns based on everything I've heard so far.

[Jim Griffin]

Brett,

Horns alone are not the holy grail. Line arrays can be realized by both direct radiators and via horn loaded drivers.

Jim

[Brett]

Originally posted by Jim Griffin
Horns alone are not the holy grail.

Where did I say they were? I simply said that based upon what I've heard so far, horns have better dynamic and transient capabilities. Everywhere.

Line arrays can be realized by both direct radiators and via horn loaded drivers.

Bit hard to use LA horns in a domesic situation below a couple of hundred Hz though. For stadiums they're a good idea.

[GM]

>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).

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Even most wide BW drivers have combing within themselves and why they often need phase plugs.....

Really, in a round about, but technically incorrect IMO, way you're agreeing with me in that if you have enough drivers of the right properties/spacing there's so much comb filtering that the brain overloads and sums them to discrete frequencies.

This is the mechanism that surround sound is based on, i.e. a significant number of insignificant sources.

Over a fairly narrow BW comb filtering sums in an increased nearfield, but this is limited to ~1WL of the line, so a long line must have a bunch of acoustically small drivers to increase its usable BW, but the mechanism is the same, massive comb filtering. The only 'lines' that sum with no comb filtering over a wide BW are compression horn arrays. These are truly fearsome performers, as is their size/cost, but the tradeoff is increased distortion.

Not many 'free lunches' in audio.

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>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.

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OK.

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

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Not knowing their design details, I can't comment beyond what I've already said.

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>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.

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Right, and there's no contradiction. Each discrete line has no power tapering, such as your Linus array does, and they are each well within the 1/3rd rule of thumb XO 'driver' spacing. To make a single line 'line' array cover a very wide BW means a row of 3/4" dia. tweeters EQ shaped to handle a much wider BW, with a substantial tradeoff in efficiency/dynamics.

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

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Hmm, I didn't say 'best' since we've been discussing arrays composed of point source drivers, but even if limited to multiple compression driver horn arrays I'm still not sure I agree. With current technology, I believe the best would be a huge fullrange Unity concept horn, but how much better it would audibly perform Vs a well done compression driven array is anybody's guess.

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>BH:

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?

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These are two different things, though often incorrectly used interchangably. Transient response is how well the speaker tracks the signal's leading attack/decay, while dynamics is how close to 'live' the speaker can reproduce the signal, i.e. its dynamic range without compression. IOW a speaker can be transient perfect, yet be lacking in dynamics due to low efficiency or thermal power compression.

WRT various design topologies, right, the smaller/greater quantity of drivers, the wider the usable BW and the less we're able to discern the negative effects of comb filtering on transient response, and of course the more drivers in the line, the greater its dynamic range.

GM

[Bas Horneman]

GM,

Thanks for your reply.

Now for something completely different.

Dunno why but don't like the idea of placing drivers all neatly in one line!

Is there any advantage in placing the drivers in a line array....ever so slightly off center from the vertical line??? Say maximum 1 inch? Or is it then not a line array anymore.

Or the one driver 4mm higher than the previous driver and the next just 1mm away from the bottom one and the next 3mm from the driver. I.e. small enough that it is still a line array but not equi distant?

Cheers,
Bas

[Pete Mazz]

Here's my latest foray into LAs.



Reading JGs original paper got me interested a while back and I've been playing with variations of these for months.

Pete

[Bas Horneman]

Pete,

They look great! Do they sound great?

What drivers did you use? Dipole as well?

Cheers,
Bas

[7V]

Originally posted by Bas Horneman
They look great! Do they sound great?

What drivers did you use? Dipole as well?

Ditto, Dave. Brilliant stuff.

[GM]

>GM,

Thanks for your reply.

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You're welcome!

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>Now for something completely different.

Dunno why but don't like the idea of placing drivers all neatly in one line!

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Can't imagine why, but whatever 'floats yer boat' since you're the one that's going to be listening to them.

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>Is there any advantage in placing the drivers in a line array....ever so slightly off center from the vertical line??? Say maximum 1 inch? Or is it then not a line array anymore.

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It's still a line, just one with a ~4316Hz offset from top to bottom that increases with increasing frequency. Don't have a clue if it would audibly impact the stereo imaging/transient response negatively.

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>Or the one driver 4mm higher than the previous driver and the next just 1mm away from the bottom one and the next 3mm from the driver. I.e. small enough that it is still a line array but not equi distant?

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This would unacceptably increase lobing, making for a too 'phasy' sound IMO, but there's one way to find out for sure, so how about cobbling up some and let us know.

GM

[7V]

Originally posted by 7V

Ditto, Dave. Brilliant stuff.

Pete, I meant Pete. What am I on?