Line array info (1 Viewer)

[Danny Richie]

I guess I'll start with this one.

Centered on the same freq. and over the range of this transition, if you can shave off 6dB through absorbtion, you'll maintain flat on-axis response.

It was here that you are off a little, but you are doing great to get this far.

Adding the dampening material all around the drivers will not bring down the level of the highs in any way. You will only make the baffle step loss start out slightly higher up the frequency range.

It would be like mounting the drivers in a sphere.

Keep in mind 1250Hz has a wavelength of about 10.5" long.

Get it?

 

[Bill Fagal]

Also, I've wondered about layering felt OVER {emphasis added} perhaps the top and bottom third of an array's drivers, starting with one thin layer and progressively thickening it toward the ends.

In both cases, I'm assuming an occlusion of at least half the cone area with material that absorbs HF energy. (Your use of the phrase "all around the drivers" just made me want to be absolutely crystal clear on that point.)

Get it?

(Just kidding, bro!)

Thanks again for your input, Danny. I'm not familliar with you or your work on arrays, but it sounds like you've gotten your hands dirty.

If I'm still all wet, I look forward to another thorough toweling-off from those more wise than I.

Bill

 

[Danny Richie]

Thanks again for your input, Danny. I'm not familiar with you or your work on arrays, but it sounds like you've gotten your hands dirty.

You might want to click on my profile icon. You will then see a link to the home page of the company that I own. You may have heard of us.

I have designed many line sources including a kit that we offer (seen at our web site) and several larger commercial models that belong to some other companies that will be released soon.

 

[Bill Fagal]

You might want to click on my profile icon. You will then see a link to the home page of the company that I own. You may have heard of us.

Ah, Yes! You had the tone of authority. Sorry I didn't recognize you. Congratulations on your successful product line, testimony to your grasp of array theory. Obviously, I'm still learning (and hope never to stop). Thanks again for taking the time to chat about arrays.

As long as I've been clear enough, I'll stop publicly flogging this dead horse of a theory (though I don't promise not to fiddle with it behind closed doors).:b

Tschuss,

Bill

 

[Hank Frankenberg]

Bill, who's going to vacuum the dust off the top surface of the foam wedges on a weekly basis? Just kidding
Thanks for the clarifying drawing - didn't realize that you were talking about wedges that long. I'm intrigued by your ideas, particularly the felt thing. Any acoustic solution in lieu of crossover components is a theory worth investigating, IMO. I (and Danny I think) misunderstood your original post in thinking you were talking about felt alongside the midwoof line. Covering most of the front of the midwoof drivers with felt: how about this: facing the speakers, imagine 2 long triangular pieces of your felt that cover the top and bottom thirds of the drivers, with the top triangle's base at the top of the top driver in the line, and the bottom triangle's base at the bottom of the bottom driver. The triangles (isocolese) taper down to the last drivers in each third, covering a smaller surface area of each driver going towards the center of the speaker. I wish I could post a drawing - I'm probably not explaining this very well.
Keep up your pursuit of avoiding crossover components.

 

[Danny Richie]

Bill,

When you cover up that much of the driver only the highs will pass through unaffected.

You will increase the baffles step loss by further dampening the lower frequencies. Because the low frequency wave lengths are longer they will not be able to pass through the openings without being effected.

Sometimes though the best way to learn and understand is to try something and see what the effect is.

If you had the ability to measure it then my advise would be to build it and do what you can with it.

It might wind up fine for acappella music since the human voice can only go so high anyway.

 

[Bill Fagal]

Danny,

Thanks for your input. I'll put it to a test sometime.


Hank,

Yeah, sorry, I should have led with a picture. Sometimes it's so clear in your own head, you don't realize you aren't communicate'n.

Now that I'm drawing...

http://image1ex.villagephotos.com/pu...sp?id_=2231680

Array A is what you're describing, right? Along those lines, I might suggest something more like array B. Just thinking that you might want to keep the treble coming from the cone centers while attenuating the slightly lower freqs. and out of phase garbage launching from the wider cone diameters.

I really dunno if any of this has merit, but I agree that acoustic problems are the best treated acoustically.

I'd like to experiment with targeted absorbtion treatment of single widband drivers, too. Their lobing and tilted response make them good candidates, IMO.

Bill

 

[Hank Frankenberg]

Bill, I was thinking of "A" alright. Interesting discussion, but, as Danny said, try it and measure.

 

[Mark_J_H_Jr]

I started this thread and got side tracked by a family medical problem. I would like to follow up now.

I do have a better understanding of the line arrays after reading this thread, although quite a bit went over my head.

Unlike Greg, listening to ear bleeding SPLs is not what I am shooting for. The few times I really crank it are few and far between. I would like to find a speaker that has detail at low volume levels and will work with home theater as well. I have a room all to myself in the basement so WAF is not an issue. The room is 20 x 23, with the listening position 11 feet from the speakers.

I assumed that after reading the white papers and from Rick Craig’s site, the line arrays might be efficient at low volumes and would still handle home theater. Sorta, the more drivers the less they are pushed. But from Greg’s comments this does not appear to be the case.

Danny,

I have heard Brian Bunge’s A/V-1+s at a little get together we had in Atlanta a while back. They were compared to 3 sets of speakers; Swan Diva 4.1s (mine), Paradigm 100s and M & K (forgot numbers). Outstanding speakers!

How would you compare the line arrays you built to the A/V-1+s?

Maybe I should start another thread of “What DIY speaker sounds as good as Maggies for music, but has dynamics for home theater?”

 

[Danny Richie]

Hello Mark,

Yes, the line source designs are very capable of handling low volumes and home theater very well.

I am glad you got to hear our A/V-1+'s and liked them, but the Alpha LS is not in the same league. The Alpha's blow them away in every way (except for maybe WAF).

Like I said before, if you want to hear a set of line sources, to get an idea of the capabilities, there is a pair in Atlanta and the owner loves to show them off.

He uses them for two channel and home theater.

 

[Greg Monfort]

> started this thread and got side tracked by a family medical problem. I would like to follow up now.
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Hope everything turned out well.
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>Unlike Greg, listening to ear bleeding SPLs is not what I am shooting for. The few times I really crank it are few and far between.
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Hmm, listening occasionally at ~'live' levels are 'ear bleeding' only if you do it for long periods on a regular basis, which I don't, but when I'm in the mood to I don't want the sound going into high enough distortion to detract from my enjoyment. Effortless dynamic range cabability pays dividends at all typical listening levels, not just to increase your pain threshold.
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> I would like to find a speaker that has detail at low volume levels and will work with home theater as well.
I have a room all to myself in the basement so WAF is not an issue. The room is 20 x 23, with the listening position 11 feet from the speakers.
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Then horn, electrostatic, or large dipole, all with clean/efficient midbass sections and plenty of clean sub output.
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> assumed that after reading the white papers and from Rick Craig’s site, the line arrays might be efficient at low volumes and would still handle home theater. Sorta, the more drivers the less they are pushed. But from Greg’s comments this does not appear to be the case.
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Nope.
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>Maybe I should start another thread of “What DIY speaker sounds as good as Maggies for music, but has dynamics for home theater?”
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Planar dipoles do some things really well, but getting them at a higher efficiency means horn loading very efficient ~fullrange drivers, then mating them to an equally efficient midbass/sub system. Expensive, at least by my standards, and requires enough space to reduce listening distance at least 2ft.

GM

 

[Mark_J_H_Jr]

I have to agree that listening at live levels is for a short period only.

Greg, I'm not sure what you mean by:

getting them at a higher efficiency means horn loading very efficient ~fullrange drivers

Could you expand that a bit?

I'm still not quite sure why I am so mesmerized by planar speakers. Every time I have heard a Maggie set up I have been impressed. The lower volume ability and a nice surround effect.

Danny, I sent you a PM.

 

[Greg Peniston]

For a look at some extreme line arrays there is a pair at Audiogon that utilize a total of 100 drivers. E-mail for pictures.

 

[Greg Monfort]

Planars have large diaphragms so they have a much better acoustic impedance match to the air than a small point source so they don't need to move as much. This allows their diaphragms to be very light so have a very fast attack/decay capability and good phasing. Add the fact that dipoles don't have any box colorations and interacts less with the room and it all adds up to a pretty accurate reproduction of the signal over a fairly wide BW. Unfortunately, all their plusses make it expensive to blend in the rest of the BW.

Horns trade large cabs, varying degrees of box coloration for varying amounts of increased acoustic efficiency (flare rate dependent) and reduced room interaction. When horn loaded, ~fullrange drivers can have as wide, or wider ~flat BW/power response as planars, with excellent phasing, highly damped (fast) transient response, and very wide dynamic range.

Since well designed horns can do everything planars do except in spades, blending in the extremes of the BW tends to get expensive.

That said, I just found out that Lowther's latest full range offering (expensive) is quite the performer and might be a good compromise between planar and horns in a bit more compact package.

Elaborating on an earlier response, line arrays are only as efficient as the compensated passband is so you can get fairly high efficiency out of them, but you have to use expensive HE drivers, which jacks up the cost considerably.

Rather than a line array per se, a slightly concave curved or stepped WWMMTMMWW dipole line (or similar) might be a better solution to get a reasonable footprint/HE/power tapering/good phasing since power tapering is required anyway. Start with a 94-96dB HE fullrange designed for horn loading for the ~500Hz-20kHz BW (T) and suitable midbass/mid drivers for ~80-500Hz (M), with some dipole sub drivers to raise efficiency a bit lower for a good blend to a high performance, critically damped sub. Not cheap, but done right would be very impressive and I believe would meet your stated performance goals 'close enough' with enough dynamic headroom for an effortless sound at HT and most 'live' levels.

GM

 

[Mark_J_H_Jr]

Greg,

I think I am following you. I understand the eccentricities of planar speakers. I am partial to the amount of detail they add to the musical soundstage.

Since well designed horns can do everything planars do except in spades, blending in the extremes of the BW tends to get expensive.

When you talk horns, I think of Klispch. I have not heard a Klispch I could live with long term. What speakers other than Klispch offer well designed horns, and more specifcally, are there any DIY horn projects that you know of?

You did not mention ribbon tweeters. What are your thoughts about how they compare to horns?

 

[Greg Monfort]

>When you talk horns, I think of Klispch. I have not heard a Klispch I could live with long term.
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'Klipsch' and 'well designed' are for the most part mutually exclusive IMO, though Heresys can be tweaked to a modicum of acceptability IMO. Otherwise, might as well substitute B*** in its place IMO. Lamentably this applies to the majority of consumer horn systems. The truly good ones are so expensive/limited appeal they are special order, like Wilson, etc..
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>What speakers other than Klispch offer well designed horns, and more specifcally, are there any DIY horn projects that you know of?
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There are myriad iterations out there right now, most designed using tractrix flares. Bruce Edgar's designs are the most popular and well thought of sonically among the horn cognoscenti, and IMO, reasonably priced whether DIY or finished. I haven't auditioned his latest designs, but know enough about horn design to know he understands what's what and doesn't take the shortcuts that audibly deteriorate the sound as so many do. S-B makes beautiful/finished lathe turned wood tractrix 'salad bowls', but are much higher priced of course.

Neither BE or S-B do FR driver horns AFAIK though, instead going the traditional prosound route of using a different horn every BW, so an entire system is LF/midbass/mids/HF. AFAIK they don't do sub basshorns due to their extreme size, etc.. These really need to be designed/built into the room. HE IB is the best alternative.

There's a new manufacturer that's just begun marketing one using one of the better Fostex drivers, but don't know much about it yet. Whether it would be suitable for your app. depends on what tradeoffs they chose.

The only other one that springs to mind is the Oris which uses either a Lowther or Supravox and while I'm confident it would satisfy, it wouldn't surprise me though if buying a used car and season tickets to the Met is cheaper.

Bottom line, horns are like any other cab design, ergo ideally need to be designed/optimized for your app., so scratch DIY is best.
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>You did not mention ribbon tweeters. What are your thoughts about how they compare to horns?
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Ribbons are fantastic, but the only HE ones I know of are the Ravens. Between the price and inevitable element replacement if you don't XO them high, defeating much of their sonics, 'quoth the Raven, nevermore'. If you run ribbons ~floor/ceiling to gain efficiency their pattern notches as you move up/down. Bothers some, others not. XO'd >5kHz and they appear to smooth out though due to our falling hearing acuity.

GM

 

[Brett DiMichele]

I have some questions....

Bear in mind I don't know $hit from Shinola here so don't
smak me in the head too hard!

If you lowpass the line array at say 80Hz with a super steep
roll off and use a good sub woofer or sub woofers to pickup'
from 80Hz down then does this not make the job of the mid's
substantialy "easier"? And would this not open the choice up
to a whole lot more drivers that have enough excursion to
play in that range?

Danny,

On the Alpha LS's why were the Neo8's used instead of the
RD-50 or 75's? I haven't looked at the specs recently. Do
the Neo's extend higher than the 50's and 75's which roll
off at 18Khz I think? I am just curious..

I want line arrays bad... I really want to build the set
that Jon Marsh was (is?) working on.. I haven't bothered him
to see what's going on with the progress because of his back
injury and all.. That's a "down the road" goal and it's not
something I am delving into overnight anyway.

 

[Danny Richie]

Brett, I would still never cross a sub as high as 80Hz, and you would be hard pressed to find any sub that sounds as good as the Alpha's from 30Hz and up.

Multiple drivers can pound out low bass with much more speed and much less distortion than a big woofer.

Each of my Alpha LS speakers can hit as hard or harder than my 12" sub can, easily. And this is a hefty sub.

As for the ribbons:

The Neo's sound better, are better controlled, have a much faster and cleaner spectral decay, and a lot higher sensitivity.

At one meter the RD ribbons are about 85db while each Neo 8 is 93db.

If I used the RD ribbon instead I would have to pad down the woofers to match the sensitivity. This creates lots of problems. It would really have to be bi-amped to get it to even work properly.

 

[Brett DiMichele]

Danny,

Thanks for the info!

I assumed that it was a sensitivity issue with the neo's.
I guess it only goes to reason there is less membrane per
neo to move and the transients and decay would improve. But
I am sure the RD's don't sound "bad" either.

Another question, since they roll off at 18Khz how fast do
they drop, do you get anything in the 19Khz range? I am
asking because I see that BG also has a ribbon with a super
tweeter midflanked between two smaller ribbons. It obviously
must not be a real huge comprimise or you wouldn't have
used the Neo's in the Alpha's. Wish I could hear a set...

As far as the subs go.. In a sealed enclosure seperated
from the line array's with the right driver 80 or even 100
Hz isn't out of the question. I am in no way doubting the
capabilities of the Alpha's mids to produce real quantative
bass output. But for my sake and to aid in driver choice
(to save money....) I will be using subs to do the low end.

This is unless sometime between now and next year I just
decide I can't DIY something of this magnitude and just buy
a prefab kit

 

[Danny Richie]

Wish I could hear a set...

Maybe you can. What part of the country are you in?

And I would still recommend subs not playing that high.

You will also get some bottom end gain from running multiple drivers in an array. If the woofer you choose models to be -3db at 60Hz then by the time you build an array using 9 to 12 units your actual -3db down point might be more like 52Hz or so.