line array build questions and pictures

[lolojr1]

this will be the first post at my first line array design / build

please comment and ask questions about anything

im not to concerned about total sound quality or maximum spl but to learn and experiment and have something really cool to show to friends would be nice too

my first major hurdle is how to mount my speakers, i have (36) 2.1"x3.7" rectangle speakers per side

http://s270.photobucket.com/albums/j...ent=100001.jpg

and (12) 4" round speakers per side no close up yet sorry

http://s270.photobucket.com/albums/j...rent=00004.jpg


the round speakers will be cake, a hole saw the right size has already been purchased and test fitted to be perfect

the rectangle speakers will be a pain,i have 2 ideas so far please tell me what you think

option 1

drill a hole at the depth of my drill pres's throat's depth, roughly 4.25"
36 times at a spacing of the width of the speakers shortest dimension 2.1" then rip the piece in 2 through the center of all of the holes to form 2 pieces of wood with 36 half round shapes cut out of them and then attach the speakers leaving a small opening at each end of the line to be filled in after assembly

option 2

make a jig and router out a template for each speaker individually

i have a problem with each option

option 1

the baffle is not going to be one piece of wood making it seriously weak and the speakers have a plastic basket so i don't want to break them with the stress.
i can then double face the baffle in witch i can then cut out a large rectangle and recess the speakers with a round over bit or a chamfer depending on my mood or just double the back up and laminate the front to make a smooth continuous look.

option 2

if my template is just slightly off in its dimensions they will compound and my center to center spacing will be off the farther down the line i work.

doing that much routering is going to be a pain. its going to make a huge amount of dust. its winter and its cold here my garage isn't heated and i store my custom car tons of tools ,electronics and stuff i generally wouldn't want to cover in mdf dust i can work with the door open for a while and do some work in the driveway or just move the car out until it snows


has anyone ever done this type of build ?

how did you cut the holes

[lolojr1]

oh i will be making these open baffle and i cant decide how wide to make the baffle

i had the graph with speaker size on one axis and low frequency on the other axis but i cant find it anymore anyone have this or know where to find it ?

and also all voice coils are 8 ohm so i am working on my wiring configuration now

[lolojr1]

well after wasting a whole sheet of 1" mdf i had a great idea

i was thinking on mounting the speakers to the front or rear of the baffle but i couldn't get a place to put a screw due to the odd shape

so i took the router and made a slot all along the length and made a channel to slide all of the speakers into


here area a few more pictures

the first attempt -failure




then the final roundover of the new and improved design




i just bought this circle/edge guide and im not impressed at all with it




although i do love my ripmaster

[auplater]

here's the 1" cherry (four boards biscuited together) to make a 6' h x 21" w baffle for my linesource using BG 75's, etc. from 3 years ago..

Note the clever glass template for cutting the mid woofer holes





finished speaker



The long slot looks to be the way to go. looks like you need a little more shoulder to mount the screws. You might also run a cross brace every 3 or 4 speakers to strenghten the final baffle.

I bought a jasper jig for circle cutting after this project... wouldn't be without it for future projects

John L.:

[lolojr1]

hose are gorgeous cherry wow im using mdf haha

i am actually going to use a slot and just slip all of the drivers down it no screws at all

i think it might leak a bit but its a learning experiment what the hell right if its bad i can silicone or hot glue between the drivers

im running the woofertester 2 right now just to see what they have for specs

the first draft will be about 5" wide by 8" deep and the driers are going to be mounted about 3/4" back

i wanted the jasperjig but saw this and it was on sale i should have thought it out cheaper isn't always better !!

i will have a few more pics in a while

[lolojr1]

here they are installed just temporarily though

i have to do the wiring next week and cut the sides to length but its getting there







not much room for wiring is there?

[auplater]

That's a clever way to "stack" them... you might need to stuff some loose batting behind the drivers if you hear any cavity resonance... may sound alittle "one note boomy" without it.

Here's a close up of the cherry "figure"



What drivers are those? The baffle width will determine the low frequency response (aka baffle step) which you can compensate for to some degree in the xover. Mine ended up @ 21" width, which, iir, works out to ~310 Hz where the radiation changes from 1/2 space to full space (baffle width = 1/2 wavelength).

I added the back swept wings to increase the width and also decrease the perceived footprint viewed from the front.

Here's where they live now...



John L.

[lolojr1]

i dont know what manufacturer they are i got them on ebay about 2 years ago when everyone was doing the nsb line arrays

i can give a woofertester output if you like but its on my other computer that isn't connected to the net right now

they had a cup over the bucking magnet but i took it off due to it being bigger than the largest dimension of the basket now there is just the magnet and some glue i have to get off

i used to have all of the info to design these when i bought them then i converted from m$ xp to Linux Ubuntu

could you send me in the right direction to find the baffle step graphs and such i cant remember where to find them

i dont think they are going to go to low and that is why in the first post i have a dozen 5" drivers just in case they dont , i will ad another line to the side with those although i dont want to get into xovers just yet

they have an fs of 165 hz kinda high i think

well the wiring should be a cinch, 6ohm drivers at 36 each comes to a 6 ohm final impedance i will even be easy to wire up



do you have xp running on your TV? if so nice i like that i bet it would look really cool with the electric sheep screen saver (google it its really cool ) running on it and those beauties playing your favorite tunes

and what is the long driver on the right in the close up that is aluminum colored?

[sumacSK]

Hi,

Nice project.. It seems that upper freqv. limit for those square drivers will be around 6.4kHz (based on your dimensions). Are you going to use tweeter line too?
I think that those 4" drivers are not going to be enough for serious low end... If I were you I would rather use stereo subs instead of those 4" speakers array..

good luck
Martin

[lolojr1]

how do you know it will only reach up to 6.4k hz? and what affect will longer/shorter sides have on low frequency ? what should i expect the to go down to ?

i will be testing the results and will posting them here when i am done building (audiocontrol 3050)

the 4"rs were a really good deal so i bought them too if i need them i have um thats all or i might do another array all together

i do have 2 8" woofers i could add to thisn a small box in the base or something similar.

i currently use 2, 12" subs for low end in a somewhat large ported enclosure with about 400 watts each

and one other thing with the wiring
i have 36 drivers per side this gives me easy wiring
6 parallel sets of 6 series drivers to achieve a impedance of the same as one driver 6.4 ohms .

is there a better way to wire the paralleled sets series or the series sets paralleled ? the final impedance will be the same but will either way affect final outcome?