Starting to plan out a pair of Massive Line Arrays (MLA)...

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Eventhough I love my fairly new large open baffle loudspeakers (Usher Audio D2 clones gone open baffle), they are simply too dang large for this room, eating up way too much space in my theater/listening room. They sound great and have more than plenty of oomph with very little power. Gotta love that high efficiency!

I have always been highly interested in line arrays and have decided to finally build a pair, a large pair at that, with a large, matching center channel.

To fund this rather costly project I'm going to be selling off all five of my Usher Audio drivers AS WELL AS all three of my Altec 511B horns and 902-8 drivers. So if anyone is interested in purchasing any of these, please let me know.


Anyway, before I tell you about the drivers I'm going with, I want to explain the reason I chose the woofers. A few months back, one of my brothers bought the Dayton BR-1 6-1/2" 2-Way Monitor Kit Pair from PE when they had them on sale. I helped build the crossovers for him while he did most of everything else. To make a long story short, these little things put out the most amazing, low bass for such small speakers! In his room, they have solid output down into the mid-30's easily! And that's without any tone controls of any kind!! :bigeyes: They also have excellent midrange that's very full, clean and natural sounding.

So for the very reasons stated above, I'm 99.9% sure I am going to go with a large number of Dayton DC160-8 6-1/2" Classic Woofers, somewhere on the order of 10 drivers per channel (3 channels total). I figure that if those little kit bookshelf speakers put out that kind of bass and midrange with ONLY one driver, ten drivers in a LA should be that much better reaching down into the low-mid 20's, especially when you take into consideration the higher efficiency and lower distortion.

To finish the LA's off, I'm going to go with a bunch of the Dayton PT2C-8 Planar Tweeters, I'm thinking 5 per channel should do it.

They'll be crossed over at 2100Hz via my DCX2496 at 48dB per octave. The reason for choosing 2100Hz is because that's what those kit bookshelves of my brother's is crossed over at, and because the planar tweeters should only go to about 2kHz when used in multiples. Who knows, maybe I can get them down a little lower around 1.5kHz or so since I'll be using so many.

The enclosures will be 10x the size of the kit speakers which are 0.55cf tuned to 41Hz. So that means mine will be 5.5cf, and I'll have them tuned slightly lower to 38Hz with three 4" flared ports down near the bottom of the rear baffle.

I know these aren't the greatest drivers out there, but they aren't junk either, and I already know very well what one of these 6.5" drivers are capable of. And as it stands, just the drivers alone is going to cost me over $1k, so I really can't go with anything better than these ATM. But I feel that these two drivers should get me some pretty decent sound, and with much narrower, shallower speakers than what I have right now.

So what do you all think? Please let me know! ;)
 
I "see" to many problems, like the Fs for that to many drivers (is not the same between them) and will cause vibrations.
Read about mr. Bose 901's patents & evolution. They (speaker drivers) are isolated from each other. So, two woofers might pose a similar problem already. (note: I never tested this.)
 
"I know these aren't the greatest drivers out there, but they aren't junk either"

Those drivers are gonna sound great. I played around with arrays for a coupla years and they are very forgiving of driver quality. My only suggestion is to use at least 8 of the PT2 tweeters if you can swing the budget, and you can never go too tall with them.

These were built as a "sit-down only" experiment and were the last attempt of mine to make something look nice. :D Eight 5-1/2 peerless buyouts from PE and eight original version PT2s. They ended up being my reference to beat speakers in spite of being too short. You'll probably love yours when they're done.

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AJ said:
"I know these aren't the greatest drivers out there, but they aren't junk either"

Those drivers are gonna sound great. I played around with arrays for a coupla years and they are very forgiving of driver quality. My only suggestion is to use at least 8 of the PT2 tweeters if you can swing the budget, and you can never go too tall with them.

These were built as a "sit-down only" experiment and were the last attempt of mine to make something look nice. :D Eight 5-1/2 peerless buyouts from PE and eight original version PT2s. They ended up being my reference to beat speakers in spite of being too short. You'll probably love yours when they're done.

An externally hosted image should be here but it was not working when we last tested it.

I've seen pics of your setup before. NICE! I'm looking forward to getting this project going. The best part of course will be when I bring them to life. If I can afford more drivers at the time, then I'll definately get them, but if not, I'll leave space on the baffles to add onto it at a later date. :D


pedroskova said:
Is this going to be an OB LA or a sealed LA?

WIth your digital set up, I'd go OB.

They're going to be 5.5cf ported and tuned to 38Hz or so.
 
GR research mid/woofer M130 is very good for the money and very efficient at about 89-90db, for 8 ohm version. I have used them myself, costs $24 each. Good value, very sweet mid range easily cross at 200hz and 2000khz.

they are used in LS9 array speakers by GR research. It is worth a look.

I have no connection to the company just a happy customer.


Cheers.
 
line source

I went with planars... the neoplanars are good down to ~ 300 hz, the BG 75's are crossed @ 600 hz...I used peerless 6 1/2" mid woofs for 300 hz - 40 hz, and 2 12" sonosubs for low end duty..

you'll love how they fill the room, you might want to consider ob for higher frequencies at least if you have room

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


John L.
 
Through a little more research, thought and planning, I have revised the plans for the MLA's.

As far as drivers are concerned, I really won't have much choice but to go with the Dayton Classic 6.5" drivers. They are the only ones in my price range, not to mention that I know exactly how they sound and what they are capable of.

What I will do to help these drivers out as much as possible is to implement a Zobel network into the design to flatten the impedance as well as implement a parallel notch filter to tame the 3.2kHz peak. Of course, I will be hounding you guys for pointers and advice on these two circuits since it will be the first time for me ever attempting such a thing. Keep in mind, these will be the ONLY two passive circuits in the entire project. As far as crossover, time alignment and EQ duties are concerned, I'll be using my Behringer DCX2496. I hoping that I will not need to use much if any EQ at all on these speakers. The less EQ the better, but I am not against using EQ at all.

I was also thinking, with the Zobel and notch filters, I could possibly raise the xover point a little to maybe 2.5kHz. Would this be alright since the notch filter will be in place and the fact that the xover will be at 48dB per octave? I'm thinking that that 3.2kHz peak from the woofers combined with the notch correction and sharp xover rolloff will be almost nonexistent.

After re-reading the specs on the Dayton BR-1 kit, it is actually 0.52cf tuned to 38Hz. However, I am still going to design mine off of the idea of 0.55cf and will tune a bit lower.

Now here's the twist... Instead of using 10 drivers per channel, I'm going to go with 12 per channel, and I'm going to tune a bit lower to 35 or 33Hz (33Hz is the FS of the driver). Having 12 of these drivers in a line, they are going to be just about 78" tall from basket edge to basket edge. With that in mind, I am going to have the enclosures exactly 84" tall (7ft). This will give me 2" above and below the outer-most drivers. And for the Dayton PT2-C's, I am bumping up the quantity from 5 per channel to 8 per channel.

As for the center channel, I am starting to think that I don't have to build it as large as the mains. In fact, I'm almost certain of it. That would just be a majorly huge center channel and it's probably not necessary. I have a couple questions about the center channel as well...

1) What would be a good number of drivers to go with?
2) Since this will be a horizontal speaker, would I also have the tweeters mounted horizontal or would I flip them 90 degrees and have them vertical, maximizing the horizontal projection of the tweeters?

So what do you all think?
 
chops said:
I was also thinking, with the Zobel and notch filters, I could possibly raise the xover point a little to maybe 2.5kHz. Would this be alright since the notch filter will be in place and the fact that the xover will be at 48dB per octave? I'm thinking that that 3.2kHz peak from the woofers combined with the notch correction and sharp xover rolloff will be almost nonexistent.


Actually, I just read a reply on another forum that this will not work since the cetner-to-center spacing of the 6.5" drivers will be too far apart for even a 2.1kHz xover point, much less a higher point like 2.5kHz stated above.

Hmm... Back to the drawing board. :whazzat:
 
driver placement

I'd think wertical mounting of the tweeters for the center channel would be the only way to minimize floor reflections muddying up the sound... one of the advantages of the planar design is low and controlled vertical dispersion. You'd be literally turning that advantage on it's side if you mount them horizontally, I believe.

The only problem with vertical mounting (side by side I presume)now becomes on-center distance and lobing between the drivers... which is why I went with single linear non-array drivers above...

I think the upper limit for the 6.5" you have would be ~ 800 hz or so, giving 1/2 lambda of 8.5" as a minimum (still with lots of null potential) and preferably lower still, depending on how far back you sit.

If you notice, the 6.5" peerless in my setup have cutdown flanges... maybe find some cheaper versions of same (maybe in a 5" or 4.5") you could use them. I was originally gonna do a vertical midbass array up beside the BG 75's, but after using the 2 peerless 6.5" (150w rms each) in a ported communal box, I am more than satisfied with output well below 45 Hz (where my subwoofers take over anyway) ~ 107 dB @ 15' in a 12000 ft^2 cathedral ceiling room b4 noticeable distortion...all I can take:D

The BG's have a notch filter @ ~5.5Khz, and the midwoofers are zobel'ed as well

Hope this helps in some way...

John L.
 
Actually, I just read a reply on another forum that this will not work since the cetner-to-center spacing of the 6.5" drivers will be too far apart for even a 2.1kHz xover point, much less a higher point like 2.5kHz stated above.

Hmm... Back to the drawing board.


Hi,

Agree, Maybe you get better ideas if you take a look at the submitted 8(8) point source simulations:

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1(8)
 

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