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Discussion Starter · #1 ·
I've started another project. I bought 24 of these and 2 of these on a whim to build a pair of line arrays. They have eight woofers per side and they're about 4' tall all built with leftover mdf from my last project. Total cost should be under $100 for the pair. So far I have 1 nearly done and the other needs all the holes cut still. I bought a new saw and router for this project and I have to say that they're significantly better than what I had before. Perfect cuts every time as opposed to my old saw which could be off by as much as 1/4".
 

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Very nice looking project. Do you have a crossover schematic that you're going to make?
 

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Discussion Starter · #3 ·
I haven't a clue about the crossover yet. People are currently designing one on tech-talk right now but it's not finished yet. It should be done around the time I finish these.
 

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Post the link to that thread if you don't mind. I'd like to see what they come up with.
 

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Quote:
Originally Posted by ltd02 /forum/post/20864138


you don't really have a line array there...you have a tweeter on top of 8 midbass units...the two have *very* different performance.

+1.
 

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I like the idea & project.

The tweeter would not be ear level in my room. But I bet you're going to have a great time with it, especially for the cost.

I can't believe these guys haven't designed a crossover for those 5.25" $0.69 Sony's + the 100 for $85 ApexJr tweeters yet. I'd jump all over that and store it in a closet until I actually have time to do something with it.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by LTD02 /forum/post/20864138


you don't really have a line array there...you have a tweeter on top of 8 midbass units...the two have *very* different performance.

Fair enough. The original design was for 12 on each side, which was more line array like. These are somewhere between towers and line arrays.
 

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Quote:
Originally Posted by tagaiz /forum/post/20864357


Fair enough. The original design was for 12 on each side, which was more line array like. These are somewhere between towers and line arrays.

The problem with doing it that way is that the resulting radiation pattern and sensitivity mis-matches between the midbasses and tweeter will make for an interesting result, but probably not the one you wanted.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by Bill Fitzmaurice /forum/post/20865499


The problem with doing it that way is that the resulting radiation pattern and sensitivity mis-matches between the midbasses and tweeter will make for an interesting result, but probably not the one you wanted.

The sensitivity between the woofers and tweeters should actually be closer with 8 than with 12.
 

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Quote:
Originally Posted by tagaiz /forum/post/20865824


The sensitivity between the woofers and tweeters should actually be closer with 8 than with 12.

I was referring to the mismatch between 8 midbasses and 1 tweeter.
 

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The level should be pretty close right? Tweeter is rated at 96 db/w where the woofers are only 85. Not knowing how each actually performs I don't know for sure since there may be a jump in frequency at some point on either the tweeter or woofers.
 

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Discussion Starter · #14 ·

Quote:
Originally Posted by Bill Fitzmaurice /forum/post/20866808


I was referring to the mismatch between 8 midbasses and 1 tweeter.

The woofers are 85db each and the tweeters are something like 95. The difference will end up being within 1-2 db.
 

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bill was trying to emphasize the phase distortion that will cause all kinds of cancellations because of the difference in distance between the listenter, the tweeter, and each of the woofers. his point is quite valid and is the reason why there are no commercial models that employ this configuration. the effect gets worse the closer that you get to the speaker, as that starts to maximize the distance differencials. you'd have to sit 30 feet back from this speaker for it to accurately reproduce the input signal. there is no way around it. you would get much better sound quality by using the top one or two woofers as the midrange and the rest as bass woofers. you can get away with it in the bass because the wavelengths are longer, so they can be spaced wider before they begin to create phase cancellations. just trying to help. sometimes it isn't always high-fives.
 

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Discussion Starter · #16 ·

Quote:
Originally Posted by LTD02 /forum/post/20867979


bill was trying to emphasize the phase distortion that will cause all kinds of cancellations because of the difference in distance between the listenter, the tweeter, and each of the woofers. his point is quite valid and is the reason why there are no commercial models that employ this configuration. the effect gets worse the closer that you get to the speaker, as that starts to maximize the distance differencials. you'd have to sit 30 feet back from this speaker for it to accurately reproduce the input signal. there is no way around it. you would get much better sound quality by using the top one or two woofers as the midrange and the rest as bass woofers. you can get away with it in the bass because the wavelengths are longer, so they can be spaced wider before they begin to create phase cancellations. just trying to help. sometimes it isn't always high-fives.

Thanks for the help. I'm going to mess around with it once it's completed and decide from there what to do. Face it, it's a speaker with 69 cent drivers, no matter what it's not going to sound amazing. I'll play around with it and see what happens.
 

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Quote:
Originally Posted by LTD02 /forum/post/20867979


you'd have to sit 30 feet back from this speaker for it to accurately reproduce the input signal.

And don't forget about the near-field/far-field differences...
 

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"Thanks for the help. I'm going to mess around with it once it's completed and decide from there what to do. Face it, it's a speaker with 69 cent drivers, no matter what it's not going to sound amazing. I'll play around with it and see what happens."


the cost of the drivers doesn't matter. a great design can result in great sound even if dirt cheap drivers are used, it is just easier to do with expensive drivers.


do you have a frequency response plot of the mid-bass drivers? i may have another option depending on how it looks...
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by LTD02 /forum/post/20868532


"Thanks for the help. I'm going to mess around with it once it's completed and decide from there what to do. Face it, it's a speaker with 69 cent drivers, no matter what it's not going to sound amazing. I'll play around with it and see what happens."


the cost of the drivers doesn't matter. a great design can result in great sound even if dirt cheap drivers are used, it is just easier to do with expensive drivers.


do you have a frequency response plot of the mid-bass drivers? i may have another option depending on how it looks...
Here's the response plot from parts-express. I think there's a few more floating around on the tech-talk thread but this one should be close if I remember.
 

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Is that for just the woofers?
 
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