Help with Line Array wiring_Power tapering

[sqlkev]

Originally posted by JinMTVT
ok sorry for my impotant posts ..

i just understood everything in the connections by readin the nice document suggested above

are u planning to build a set of line array too jinMTVT??

i cant wait for the speakers to arrive and ill start on the project..
first things first...i'll go to home depot this weekend and buy some MDF and start routing...

im still unsure about the BSC issue..but i hope to finalize that idea from now til the weekend

[JinMTVT]

it seems to be the only way to get some SPL with quality
at a reasonnable price
( can use much lower quality and $$$ drivers since they will be driven way less than with 1-2 drivers system that'll still need to shoot out come good SPL for HT )

this system would be for living room, accompanied with some kind of subwoofer ( didn't decide on any type of enclosure yet, but should be something in the 2* 18" bipolar/Tapered TL design )
that should cover from ground to ~4-500hz correctly

still also need to make the amp
( or just buy one, i'll see ahha )

i've been interested into line array systems for about a year since i've seen DreamPipes and such and read about the theory

but just started with you guys to actually think about doing it
and realize the math and all under it!

well all in alll, it seems alot simpler than my Electrostatics i'm building for my personal room .. haha
and maybe much more rearding SPL wise

[sqlkev]

wow...an electrostatic project
i'll do that one day as i progress more into this DIY world..

i agree with you on everything..
this project is light on my pocket and it "should" give me high spl for the money...

i'm thinking of adding 2 8" woofers on each side of the array...would u think that'll compliment the array well??


btw...i bought all 32 4" pioneers for only $53.xx shipped to my house..
i'll purchase tweeters here and there to test out..
but the whole thing over all wont be that expensive..
u should really just go for it whenever time permits

[JinMTVT]

that's what i'll do for sure!

OMG all the 32 drivers for 53$ ???

where you get those?

I guess that even cheap sub quality drivers will perform quite well
when the work is divided into 32

I am still unsure on how the power and signals get distributed between all the drivers ...does it change something or ?


I cannot afford to give any suggestions or comments on your dual 8" subs since i do not know much

But personally i'll do a seperate enclosure for the subs, tooo many different parameters, and i still don't know what kind of enclsure/stuffing to use for the array .

I have so many questions that i can't find answers too ..

[sqlkev]

Jin...u could get the drivers i bought from partsexpress.com (thanks to chipco...he informed me about them )

http://www.partsexpress.com/pe/showd...number=269-570

when u buy a set of 32...each would be 69 cents

for the tweeters...i plan to buy maybe another 20 or so from steve (mr. apexjr.com)...he informed me that his $1.00 now is on sale 2/$1
http://www.apexjr.com/speakerstuff.html (its down near the bottom of the page...if u follow the link to David's project on stryke's forum...the tweeter should be 8ohm)

i'll be doing the design the same as the one Dr. Griffin showed in his paper
12 woofers that are 8ohm each CHECKED
6 tweeters that are 8ohm CHECKED


as for different power distributed to different sets of drivers..
from what i understand...all of the drivers in the line array will have a different pathlength to your ears..
therefore....giving more power to the center drivers and less to the outter drivers...that'll trick your mind perceiving that all the sound from the drivers arrive at the same time...
i hope that makes sense (i barely read the paper a day or two ago)

[JinMTVT]

that's not quite it from what i understood of the paper

giving more power to the middle speakers will direct your attention to those speakers lessening the inevitable delays from the other speakers

( normally the speakers at the exact same height than your ears will get to first, then the rest following )

That's why if take into account that fact, you can make a curved array just curved enough so that the top and bottom drivers

( depending on your design and height ) will all get to approx the same time , or be at the same distance from your ears

but i think that the tapered power method is simpler, though might not be the ideal ..

i'll see if i cannot do something about that ..
the difference in distance is minimal, a few cms i think ..

thinking about it, depending on the starting height of your array,
( from the bottom ) you could only tilt is forward slightly and resolve this problem almost complelty ..doesn't take much at the speed of the sound

example : listening distance = 4m
bottom speaker almost level with ear
rest of line to top speaker =1m
so that gives a ~4.12m hypotenuse

so 12cm roughly

[Leonidas]

I was looking for this subject :

Planning to build line array's later on this year.
Already collecting:
32(+4) 5inch w/m , did some experiments with dáppolit config and several damar coatings , measured everything with DAAS ,
16(+2) ribbon tweeters , they are , according to the Griffin papers,
the problem : minimum F ; 5000 Hz.
So I used the damar to improve the upper range of the woofers , and I'm not satisfied.
So , to be sure I found 16 (+4) midrange:
very nice , 2 inch paper and high Qts , ready for open baffle?
What to do ?
2 way ; woofers + ribbons 12+8
3 way ; woofers + midrange+ribbons 19+9+8
open baffle ; midrange + ribbons + BR wooferline ?

I stil cannot decide !!

This is going to be the biggest project I ever did.

Hope this thread is going on for a while because I'm away for three weeks now and can do with some help from you guys!!

leon

[Leonidas]

I was looking for this subject :

Planning to build line array's later on this year.
Already collecting:
32(+4) 5inch w/m , did some experiments with dáppolito config and several damar coatings , measured everything with DAAS ,
16(+2) ribbon tweeters , they are , according to the Griffin papers,
the problem : minimum XO_F ; 5000 Hz.
So I used the damar to improve the upper range of the woofers , and I'm not completely satisfied.
So , to be sure I found 16 (+4) midrange:
very nice , 2 inch paper and high Qts , ready for open baffle?
What to do ?
2 way ; woofers + ribbons 12+8
3 way ; woofers + midrange+ribbons 16+9+8
open baffle ; midrange + ribbons + BR wooferline ?

I stil cannot decide !!

This is going to be the biggest project I ever did.

Hope this thread is going on for a while because I'm away for three weeks now and can do with some help from you guys!!

leon

[sqlkev]

leon
that is one hell of a project if it ever comes alive

personally...i think a 2 way line array is more cost efficient than a 3 way...
if u choose ur drivers wisely...i dont think ull have a problem at all..
utlimately...u can use the leftover money for bass or other equipments

[Leonidas]

Hello Sqlkev

Thanks for your reaction,

I already have a mono subwoofer (bandpass - isobaric 2x 38cm-
-3db at 17 hz and 61 hz measured) a plate amp + XO included.
My proto's with the 5 inch woofers fit , in HZ and sound ,
perfectly.
I'm a bit worried about the interference of the 5inch W's at the estimated XO with the ribbons.
I wasn't clear in my first message, I think .
Sorry for that ,
So the real question is about XO at aprox 4500HZ
and expected interference of the W's ;
Anyone already done this?
What results?
And I can't figure out in my head how to imagine the
"near-field far-field"transition, I'm aware that , in my case this is going to be important.
Maybe I should read the "Griffin-papers"again?
Or anyone already done this? Please Tell !!

I know , a lot of questions , but I'm stil learning.
Sorry for my "rusty" English,
Is this "off-topic" ? or a new topic ?

Leon.