Another Line Array Project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Don't sweat the tweeters

I think you will be ok with the apex tweeters. I built a similar line array with them and I do not notice any comb filtering. I went with a three way using exceedingly cheap driver from Parts express. They have 12 @ 6", 36@2" and 60 tweeters per side. I was so happy with how they sounded ( I use a behringer ultradrive for active x-over) that I know want to replace the cheap 6 inchers but I am having a hard time finding drivers to drop in the cabinets due to the odd size and shape of the baskets and the fact that I spaced them as close as I could. It looks like you will have no problems if you needed to do the same. (lucky dog !) Nice cabinets. Good luck.

This is only my second post. I am a little hesitant to post because I am embarrassed by how little I know. I have learned a lot by reading from you all. I will try to post a picture of my speakers. Please let me know what you think and any suggestions for improvement.
Thanks to all
 

Attachments

  • messy room.jpg
    messy room.jpg
    9.6 KB · Views: 863
Understandable

You are right - I am assuming something, and that is that these are dome tweeters of some sort. The basic issue is that the wavelengths up high are an inch or two - and its pretty hard to find a tweeter that will be mounted with an inch between the centers of two adjacent tweeters. Even the really small tweeters would be a little over two inches. I guess you could use piezo buttons, but they cross so high that you'd have to use really small woofers in order to get THEIR spacing right - but you've already made that decision. That's why almost every line array I've seen (except the "pro" arrays which use horns cleavery) use ribbons OR a single tweeter. It might be cool to use one really good horn.

Best deal in that would be to buy renkus heinz microtraps or eaw JF stuff on ebay and take the horns out of it - and the crossover while you're at it. :).
 
Well with the Apex tweeters I can get them pretty close. I am also going to mount them from the back and them router out each hole to give a small horn effect. Not really sure what this will do to the sound but with tweeters that are that cheap I am not sure it can hurt to much.

After I get them all done I will do some measurements and see how it turns out. If things are to bad, to my ear mainly, I can always rethink the design. These are more of a test bed them a finally design. With the shop we have at work redone things is not that big of a deal.
 
yes indeed

That would do it - with the bonus that they look like they would go lower than the "3500" specified based on the response graph. . When you have a lot of tweeters its safe to take them a bit lower, generally. You might want to cross at 2500. This has the added advantage that the acoustic "natural" rolloff will assist your crossover, and you might be able to get away with a lower order crossover for the hight pass.

Its still too far apart for 15k - but up there a) you won't hear much, b) you are not overlapping with the woofer at all, and c) that stuff is bouncing off everything (even the box) so its all out of phase anyway esp. in a line array. Good solution.
 
apex

I was talking about the ones Chris8sirhC suggested. Meanwhile I looked at the Apex tweeters. Cool, but....

F=MV squared. A teeny magnet like that can not hope to give you good transients in the high end. It will "smear". Yes you might have 50 of them (and the spacing will be reasonable) but adding them up will not give you crisp clean highs. The force required to move a cone at the velocity required for the high hz is substantial so you need either very low mass (like a ribbon), or high Force - like a big magnet/current. I will admit however, that having like 70 tweeters has massive cool factor. :).

I think you will be better off with less of the ones from Parts express suggested by Chris8sirhC.

Also, I don't know about the horn-like effect. I had a guitar amp that used that method (rear mounting and using the baffle hole like a little horn lens) and it sounded odd. It might tighten the pattern but it might do something very strange to the frequency response. I don' know enough about horns to anticipate the effect but its an interesting question. Any horn people out there?
 
apex tweets

The apex tweets when put horizontaly give a ctc spacing of just under 1.5 inches. I think that worked out to about 18 kHz before the first theoretical comb lines. (I'm going on memory here)
Obviously these are not super quality tweets but the price was right. Also I only use them from about 6500 Hz up. They were surprizingly smooth in a line.

I am looking forward to using some ribbons one day if the wallet fairy visits.

Also, Thanks to all for the encouragement. My next plan is to try some OB NSB's .
 
OK, time for another update. I am pretty much done with one cab. and very close to finishing the other. The total tweeter count per cabs is 52. I also desided to use 1/4 MDF to mount the tweeter to instead of drilling 110 holes through 3/4 MDF. The tweeter wholes have a very slight taper to them, instead a horn or just a straight hole. Then I cut and routered the cabs so that the tweeter board mounted flush on the face. Once the cabs are all painted you will not be able to tell. I have been doing a ton of prep work to get the cabs looking as good as I can, filling staple hole, smoothing everything out......... I good friend of mine is an automotive painter and is going to be painting them black for me.


In this picture the one of the left is the finished cabs.
 

Attachments

  • dsc03378small.jpg
    dsc03378small.jpg
    21.9 KB · Views: 653
In this picture you can see the different cambers. The tweeters are totally seal off from the mids. Also there are three seperate cambers for the mids with bracing in each of those chambers. You can also see how the tweeter mounting boards are mounted nice and flush with the face of the cabs.
 

Attachments

  • dsc03379small.jpg
    dsc03379small.jpg
    23.3 KB · Views: 629
falling down

Here is a question for anybody who has built arrays that are similiar in size and shape to these. Do the cabinets stand up ok, or do they have a tendency to tip over? I am planning some array that will be about 72 inches tall. It seems like they would fall over easy.
 
Yes, I too have been waiting a long time to hear what they sound like. I have been so busy at work I have not had much time to work on them.

I was also wondering just how stable these towers where going to be. After a few carpet tests I am thinking a none oversized base might work out OK. I did design the bases on my towers to be easily removed and a larger one put in its place. Also keep in might the weight. Mine without hardware or drivers weighs in at about 80lbs each.

Thanks for all the comments guys. I have learned a ton on this board. Done think I would have done it without the vast info on here.
 
base for towers

my speakers were very similar to yours. they are surprisingly stable with the 20" x 14 " base. With a good soldering gun and some side wire strippers it won't be all that bad. My line has 60 apex tweets per side. It is sort of like childbirth, they say Mom forgets the labor after she has the child. Good Luck.

P.S I would consider an active crossover. I have found it to be invaluable with these lines.
 
Falling over

My line arrays are about 76 x 9 x 11 - and they absolutely would fall over if they didn't have a base. They sit on carpet which makes it worse. Even if they didn't fall over they would want to fall over with the brush of a shoulder or a bump from a dog in a hurry. The consiquences of falling over, are, moreover, nasty. Humans and furniture alike would be crushed - and worse, the speakers themselves would certainly be damaged. So - now you understand the gravity of the situation --- or something like that.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.