New Line Array, Advice and Input wanted

swegyptian

Hey everyone,

I am interested in doing a new speaker project, and I have some rough ideas for what I want to do, but I could really use some guidance from you guys to steer me in the right direction. My goal is make a big, rockin' speaker. Of course I want it to sound good, but nothing over the top.

Here are my ideas so far. The speakers will not need to be full range. I will use subs for 100Hz or so and lower. I already have two powered woofers that I plan on using with this setup. I like the idea of being able to upgrade things as I go, and also actually being able to move the speakers if necessary, so two parts per side is a plus.

I am planning on building a two-way line array, again for 100Hz and up. I am thinking of using 12 woofers per side, and six tweeters per side. Here are some of the products I am considering:

Woofers

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-370&scqty=24

Tweeters

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=275-085&scqty=12

I think the efficiency is pretty good, and 6 tweets and 12 mids per side should help balance out the differences in efficiency between the mids and tweets. Am I thinking correctly here? I like these products as they are pretty inexpensive. Am I going to end up with speakers that sound terrible if I use these drivers? I would love to use all Morel drivers instead, but I simply can't afford it. Even if I went for there drivers, there is still something bouncing around in my head, which is the desire to use 6" drivers instead of the 5" ones. They wouldn't cost much more, but they don't play as high. 4,500 Hz for the 5", versus 3,000 Hz for the 6". I guess I want to keep some flexibility for the crossover if I want to change the fequency a bit. Then again I really want it to make noise too, which makes me want the bigger drivers. What would you do?

Now for the rest of the gear. For amplification I was thinking of using the Crown XLS602, one for the tweeters and one for the woofers. If I run them at 4ohms, I can get 600w per channel, which seems like it should do. Or would guys rather put an 802 on the woofers, and a 402 on the tweeters?

As for the crossovers, I was planning on going active, but that's really where it ends. I was originally thinking of using the Berhinger (sp) DCX2496, becuase it does everything, but I would rather have a simple product instead, like a Rane AC22. The only issue I see is that these aren't really good sounding products, rather they are affordable pro-sound solutions. Is there something else out there that will provide a better sound quality solution? I want something with XLR out to feed the Crown amps, but is about the only requirement.

For the preamp I will be using my Pioneer Elite VSX54Tx, which also drives my center and surround speakers. It will take away the bottom end to feed the subs, and it has some built-in but elementary EQ features too. Of course it only has RCA out, so I will probably splice my own ends on a cable to adapt it. I have heard of noise issues with this sort of stuff, but it sounds like its because the ground is being dumped downstream in the signal path. Hopefully I can get around that issue though.

So that's the story that has been keeping me up at night. What do you guys think of my plan so far? Any input would be greatly appreciated.

Thanks,
Alex

ben62670

Here is a great paper on line arrays.
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
You should probably go with the six's @ 4ohms. I would also consider using 9 drivers on the mids for 4 ohms, and you can stick with 6 tweets seeing you are actively crossing over, and can attenuate the tweeter level. I would consider running 4 tweeters with the nine woofers. How are you planning to wire your array? What ohms are you shooting for, and are you planning on power tapering them? Also I wouldn't worry about how high you can go with your mid basses. You can only run 6's up to 2200, and 5's to 2500 without paying a penalty in phase, and lobing issues.

I built some custom SDA line arrays, and here is the link.
http://www.polkaudio.com/forums/showthread.php?t=53273&page=6
Post 167

Good luck, and do a lot of research!
Ben

Edit With a 24 db slope you can run those tweets easily down to 2200

swegyptian

Thanks for the input thus far Ben. I was hoping to get everything close the 4ohms. I need to do the math to check the resistance. I was just going to wire then with some sort of combo of series and parallel wiring. Is this why you are suggesting 9 woofers, so I can wire it easily for 4ohms? And you like the 6"ers overall for this project? The more surface area the better, right?

Thanks for the article link too. I forgot all about it, but I have it on my PC. I need to read it again obviously. So I can run the 6" to 2200, but above that I get comb filtering/interference issues. Am I thinking correctly here?

I also just finished reading your thread before I posted. It made me want to get the ball rolling with my setup. Your setup is awesome!

Thanks again for the help Ben. It's time for me do the math on the resistance of the drivers.

Alex

EDIT

Silly me I forgot that to get 4ohms that I would need to do 2x2, 3x3, etc. I like your idea of 9 woofers and 4 tweeters per side. I think the 6" sounds like a good idea at this point.

ben62670

No problem. If you do 3 sets of series drivers, and parallel them you get 4ohms. also the way you wire the can yield a slight power taper. The 4 tweeters I was suggesting series/parallel would also yield 4ohms. Yes you are thinking correctly:). The sixes will also dig a little deeper. More bass punch that you can feel in your chest. Even when I am only running the stereo array I can feel a real good hard hitting punch from my 6.5s. I think you will be amazed at the sound of you design. Also you can build a chamber for you woofers, and ditch your sub's boxes. Just put your subs in the base of your array then you don't have to worry about having 2 more speakers to setup. This is just a suggestion because I don't know how large your currant sub box volume is. Thanks for the compliments. 90% of my work, and building was the easy part.

Keep in touch.
Enjoy your project.
Ben

edit take a look at these too
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-374
8 4's
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-374
9 7's

What are you looking to drivethem with?
Thanks Ben

swegyptian

I think the 6s sound like a great idea, they should certainly have more impact. I need to read up on the power tapering, and how the different drivers will end up with a unique resistance depending on their order in the wiring.

I must also admit that the larger woofers are also more tempting, but I don't think I can run the tweeter low enough to get around the interefence issues considering the center to center spacing issues of the larger drivers.

I have two matching 12" powered subs, which will act as little tables for the mid and tweet arrays. I want the flexibility of them being seperate, so they are easier to move around and upgrade in the future.

I am planning on using the Crown XLS amps. My thoughts were to use 2 of the XLS602. They make 600 watts per channel at 4ohms.

http://www.crownaudio.com/amp_htm/xlsspec.htm

ben62670

swegyptian wrote: »

I think the 6s sound like a great idea, they should certainly have more impact. I need to read up on the power tapering, and how the different drivers will end up with a unique resistance depending on their order in the wiring.

I must also admit that the larger woofers are also more tempting, but I don't think I can run the tweeter low enough to get around the interefence issues considering the center to center spacing issues of the larger drivers.

I have two matching 12" powered subs, which will act as little tables for the mid and tweet arrays. I want the flexibility of them being seperate, so they are easier to move around and upgrade in the future.

I am planning on using the Crown XLS amps. My thoughts were to use 2 of the XLS602. They make 600 watts per channel at 4ohms.

http://www.crownaudio.com/amp_htm/xlsspec.htm

I would recommend staying away from the Crowns. The dampening factor just isn't there. I would recommend an Adcom GFA 555. Doubling the power only yields a 3db gain. Also maybe a GFA-5400 for the highs, or a parrasound for the highs. You really are putting a lot into your project, and you don't want to short change your amplification. Its not about watts so much here as currant;) You can get both of these cheap on Audiogon. 555's go for less than $400 bills for a good one. Not to be painfully blunt but garbage in = garbage out. Especially on the highs.

Ben

swegyptian

I actually have a Denon POA5200 now, and I was thinking of getting another one, or a 2800 to use along with it. They can both do 4ohms too. The little one will be 200x2 at 4 ohms, and the bigger version is around 350x2 at 4 ohms. So I am just throwing that idea around as well. I have been looking at the Adcoms too, and the the 555 seems really similar to the POA2800 from Denon.

And I was just poking around on ebay, and found a good deal on the 1/4" jack version of the Rane AC22, which would work well if I stuck with the "home" stuff like Denon, instead of prosound stuff.

What would you do about the crossover and amps, any thoughts?

Thanks again for your time,
Alex

ben62670

The Rane would probably work pretty good seeing that it is the unbalanced version. The Denons would be a good way to get your system up and running. They would be much better than using a Pro amp.

Ben

swegyptian

Well, I bought the Rane AC22. Now I am looking for another Denon POA5200, POA8200, or a POA2800. Hopefully this gets rolling soon. I also need to read about the power tapering sutff again, so I can figure out how to wire this stuff (aside from series/parallel).

Thanks again Ben,
Alex

ben62670

No problem. Let me know if you get stuck. Did you figure out your drivers yet?

swegyptian

I think I will take your advice and go for the 9 6s per side, run up to 2200Hz or so, and then 4 of the planar tweeters per side to take care of the top end. My 5200 should make over 200wpc at 4ohms, and I think it will power the tweeters nicely, so now I am looking for an amp for the mids.

RuSsMaN

If you do 9 woofers, do 8 or 1 tweeter. Line Source, or Line Array. 4 doesn't make any sense.

swegyptian

I'm not sure that I follow. Can you please elaborate?

ben62670

8 tweeters would be better than 4, but I am not sure what the budget is. Also the tweets that you are going to be using are 94db efficient, and the woofers are going to be somewhere around 89-91db. This will provide a good match. I like efficient speakers. My theory is why spend the money on an amp that is twice as powerful to use a speaker that is 3db less efficient. Also a lot of people read the adds about how a specific design yields better sound. Yes a nice long array of tweets would be wonderful, and you can always add them, but 4 tweets will give you an excellent sound stage. A lot of real nice speakers out there go against conventional wisdom in speaker design, and sound great. My speakers go against the typical design of a line array, but have an excellent sound stage. I have two arrays of 8 MW's, and I am only running 2 dome tweeters at the moment. I will end up with 3 or 4 tweeters per cab after doing some phase testing with the tweeter array. Domes are much harder to work with than ribbons. Just keep the tweeters as close to each other as possible.

Ben

swegyptian

I was going to put the tweeters in a nice tight line. I also thought that with the difference in sensetivity it would make sense to have more woofers than tweeters. Even with only 4, I will have 24" of tweeter per side.

RuSsMaN

A line source vs a line array. A line source, will have identical +/-1 woofers and tweeters. A line array is a series of woofers with a single tweeter placed in / near the middle of the array - usually ear level at the listening position.

The direction you are headed, I invision a limited sweet spot - which may or may not even be suited for your listening room, but will at least limit flexibility for placement in other rooms in the future.

With your selection of tweeters and drivers, you are going to HAVE to pad down the tweeter section, regardless (if you use multiples). I'd suggest a simple line array using ONE of those Dayton ribbons, and depending on your wiring - use as many of the woofers as you need to match the efficiency.

Cheers,
Russ

swegyptian

Thanks Russ. Do you think that running the tweeters at 8 ohms versus the woofers on 4 ohms, and considering almost double the power on the woofers, that I would still need to lower to tweeter level?

Also, how would I decide how many woofers I need per tweeter? The difference in efficiency is roughly 2db between them.

And I need some help conceptually as well. If I would only need one tweeter, with perhaps 9 woofers, why would someone build a line array instead? Is the intended application an important factor here? This will be in my living room, sitting roughly 12 ft from the speakers. I thought at that range my sweet spot on the sofa would sound pretty good.

Thanks again guys,
Alex

ben62670

The gain of 9 woofers vs a single tweeter would require the tweeter to be over driven to keep up with the woofer array. Also that particular tweeter is 8ohms. If I were to go with a single tweeter I would recommend a real good dome.

Ben

RuSsMaN

The tweeter won't have to keep up with the woofer array. The key is matching impedance and efficiency - the crossover will keep the tweeter within it's operating parameters. You'll end up about 95db efficient overall, and those Crown amps will be serious overkill.

That's one of the great things about line arrays / line sources - they can handle high power, but you really don't need it. At the end of the day, 10-50 watts of GOOD power, will make them sing.

ben62670

My experiences with multiple woofer is that the highs kept up well, but the mids were lacking. At the XO frequency needed for such a design(no higher than 2300) vocals will be muted, and life less. Yes the amplification Russ recommended is spot on for quality sound.

RuSsMaN

Where is 2300 coming from, just curious? His particular design? I've had line arrays crossed over from 1800 to 8000.

Cheers,
Russ

ben62670

RuSsMaN wrote: »

Where is 2300 coming from, just curious? His particular design? I've had line arrays crossed over from 1800 to 8000.

Cheers,
Russ

You have to figure out the lobing created by the diameter of the driver. The smaller the driver(center to center spacing) the higher you can cross it over at.

Have you checked out this link yet? I love page three.
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
Carver ribbons can go down to 200hz if I remember correctly.
Always appreciate your advice Russ. I may be dabbling in tubes in the future;)

Thanks Ben

swegyptian

Yup, I was taking the crossover frequency from the article that Ben posted. Apparently crossing over a driver of that size any higher than that, assuming that they are placed as close together as possible will cause cancellation problems at around 5K.

Russ, I've also decided to keep the Denon amplification. I have a 5200 right now, which is 120x2 at 8 ohsm, and 200x2 at 4 ohms. I will either buy another one, or get a 2800, which is 200x2 at 8 ohms and 350x2 at 4 ohms. If I get the 2800, I will put it on the woofers, and leave the 5200 on the tweeters.

I have another question if you don't mind Russ. Like you wrote above I need to pick the number of tweeters to go along with my woofers by matching the efficiency. How do I go about determining what is appropriate? If I had a woofer that was 3db less efficient than my tweeter, would I want two of the woofers to match the single tweeter?

Thanks again fellas,
Alex

swegyptian

So still no crossover. Mr Ebay seller thinks its just fine to wait however long he wants before he ships something.

swegyptian

Well, still no crossover, but I did get a great deal on a some amps. I got a B&K 7250 and a 3030. Woot!

swegyptian

Finally got the crossover, but now I am waiting on parts express to get the tweeters back in stock.

I am also thinking of using the birch plywood for my speaker boxes. Have any of you guys used this stuff before? I am trying to make this pretty simple, and I imagine that cutting the veneer process out of my build would make my life easier. Any thoughts?

ben62670

Venner is easy as pie. Use MDF Plywood is much harder to work with never mind SQ. Also with ply you still need to veneer the edges. Which drivers are you going with?
Ben

swegyptian

I am going with the 9 6" woofers, and 4 planar tweeters per side. And parts express finally has all of my stuff in stock. I might just need to place an order tomorrow.

I am indeed going to use veneer on MDF instead. We are going to enter the box design the CPU so we can have it CNC cut instead of actually working hard, too. Then I will just need to assemble everything and give it a nice finish. I have an idea of the volume needed per on online calculator, but I don't know the displacement of the woofer. Is it posted in here by chance? I can't seem to find it.

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=295-372&scqty=18

I think I am going to use 1" MDF for the main structure, and 1/2" MDF for the braces between each woofer. To make the calculations easier, I will just be splitting the enclosure in half, so I don't need to worry about the volume that is displaced by the tweeters.

ben62670

swegyptian wrote: »

I am going with the 9 6" woofers, and 4 planar tweeters per side. And parts express finally has all of my stuff in stock. I might just need to place an order tomorrow.

I am indeed going to use veneer on MDF instead. We are going to enter the box design the CPU so we can have it CNC cut instead of actually working hard, too. Then I will just need to assemble everything and give it a nice finish. I have an idea of the volume needed per on online calculator, but I don't know the displacement of the woofer. Is it posted in here by chance? I can't seem to find it.

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=295-372&scqty=18

I think I am going to use 1" MDF for the main structure, and 1/2" MDF for the braces between each woofer. To make the calculations easier, I will just be splitting the enclosure in half, so I don't need to worry about the volume that is displaced by the tweeters.

9 4 ohmers = 4 ohms?
You have access to cnc wood mill. you lucky guy!

swegyptian

Wait, 4 ohms with 9 drivers can be made to equal 4 ohms, right? And yes, I am very happy to be close enough to get the CNC work done, although I will have to pay for it.

ben62670

yes, and work the dough. Try to get them to do the recessing of the woofers. Shoot me a PM when you get to that point. I used a 1/2" rabbit cutter to recess mine.