Author Topic: Line Arrays  (Read 28271 times)

Offline tmazz

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Re: Line Arrays
« Reply #60 on: August 03, 2017, 05:12:38 PM »
You're lucky Rich, most wives would be saying "You really don't think you're going to bring those monstrosities into the house, do you?"  :rofl:

Oh come on, we've all been there at one point or another...... :roll:
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Offline BobM

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Re: Line Arrays
« Reply #61 on: August 04, 2017, 09:53:39 AM »
Keep plugging Rich. There's a lot of construction to a line array.
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Offline richidoo

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Re: Line Arrays
« Reply #62 on: August 04, 2017, 11:02:35 AM »
Keep plugging Rich. There's a lot of construction to a line array.

Thanks Bob, you're right about that.
Glad you're watching. :)

Offline steve

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Re: Line Arrays
« Reply #63 on: August 08, 2017, 10:21:53 AM »
Aha! Thanks for another wake up call Steve! I wouldn't make any progress without you!

I hope I am not a pest, love a great experiment/work.

Quote
You're intuition must be itchy cuz I'm actually already working on it today. I'm regluing the T nuts with CA glue because the PL construction adhesive that I used before is very strong and tough, but it doesn't wick under the TNuts to make a good enough joint. It's more like taping them on from above. I could only glue one side of the TNuts with PL while the drivers screwed down to hold the nuts in place, so some of the TNuts could rock a little on the other, loose side. The CA seeps under and glues it tight. I'm using Bob Smith medium viscosity 15 second cure, but on the rough side of the masonite it cures very slowly, but it's solid after 10 minutes. Luckily I haven't glued any fingers together yet, but there's still one baffle left. I like the first wiff of CA, reminds me of happy days in my previous stress free hobby of model airplane building. But after a few minutes the smell gets old fast.

Also today I will drill 4 small holes in each of the 64 divider panels that go between each driver, holes to allow the hookup wires to pass through. Some of the panels need less holes, according to the wiring schematic, but the most holes any panel needs is 4, so I'm drilling 4 in all of them, then I'll fill the unused holes after the hookup is done. That's easier than gluing each divider panel in a "correct" position, and messing it up. Also allows changing the wiring schematic if I already messed that up but don't know it yet. :)  Since all the drivers move the same, in same volume chambers, there shouldn't be any air movement through the holes, but I'll seal them up anyway, and the wires through the holes. Once the holes are drilled I can start the sexy job of gluing up the boxes.

Edit: My wife wants me to finish these so she can hear what all this work is for. So I am motivated to show it off for my biggest fan and that should accelerate my progress. Just don't hold your breath!  :roll:

That is one phase I don't like thinking about, making sure the nuts stay in place. I have not had any experience to see how long CA will work with wood. Will you need a combo of CA and CL to prevent nuts from falling after decades would work or just CA alone?? Using any washers, on either side??

Cheers and keep up the good work Rich.

Steve
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Offline Nick B

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Re: Line Arrays
« Reply #64 on: August 08, 2017, 10:31:27 AM »
rich, this is wery cool.  looking forward to hearing about the outcome.

eight years ago, i purchased 40 of these, and now that i am back in a house w/a big room, i may actually try to put together a line array myself:

https://www.parts-express.com/peerless-india-lko-120wff-5-1-4-fullrange-driver--299-280

i was thinking 15 or 16 per side, w/a few left over for spares.  at rated 45hz-18khz, with dsp, these could be made to run pretty-much full range at high efficiency.  as my woodworking skills are mediocre at best, i was considering simply mounting them in a baffle, and modifying a sonotube to accept the baffle. 

keep up the good work!   :thumb:

doug s.

Doug,
If you do it, you have to keep us posted on your progress, ok? I've seen line arrays a couple of times. I think years ago Audioquest produced one, or at least a guy who worked for them. It wasn't a completed speaker, so I never got to hear the final version
Nick
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Offline richidoo

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Re: Line Arrays
« Reply #65 on: August 08, 2017, 11:12:24 AM »
Quote
That is one phase I don't like thinking about, making sure the nuts stay in place. I have not had any experience to see how long CA will work with wood. Will you need a combo of CA and CL to prevent nuts from falling after decades would work or just CA alone?? Using any washers, on either side??

dougie and steve, thanks for the encouragement

CA glue is very strong, good bond to wood/metal. I think it will last. Masonite is acidic apparently, so it slows the cure of CA, but it's easily kicked off with some baking soda, or spit (if you're saliva is alkaline = young.)

It's not hard to glue on a new Tnut if one falls off, just have to get it lined up first, held in place by tape, then CA it with access through the driver opening. But better to get most of them glued on the easy way.  8)

I built these arrays of 3/16" masonite as a cheap trial just to hear what it sounds like, whether the concept deserves further development. If it sounds as good as claimed I might build it again in aluminum with rear mounted drivers.

Offline richidoo

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Re: Line Arrays
« Reply #66 on: August 08, 2017, 11:30:15 AM »
https://www.parts-express.com/peerless-india-lko-120wff-5-1-4-fullrange-driver--299-280

i was thinking 15 or 16 per side, w/a few left over for spares.  at rated 45hz-18khz, with dsp, these could be made to run pretty-much full range at high efficiency.  as my woodworking skills are mediocre at best, i was considering simply mounting them in a baffle, and modifying a sonotube to accept the baffle. 

Great idea! With 20W power handling each you can EQ the bass to ur heart's content.
I thought about using preformed tubes for the cabinet like PVC pipe or sonotube. As sealed box, and high power handling, and intending to EQ anyway, the box volume isn't so critical.

Offline dBe

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Re: Line Arrays
« Reply #67 on: August 13, 2017, 03:15:23 PM »
Aha! Thanks for another wake up call Steve! I wouldn't make any progress without you!

I hope I am not a pest, love a great experiment/work.

Quote
You're intuition must be itchy cuz I'm actually already working on it today. I'm regluing the T nuts with CA glue because the PL construction adhesive that I used before is very strong and tough, but it doesn't wick under the TNuts to make a good enough joint. It's more like taping them on from above. I could only glue one side of the TNuts with PL while the drivers screwed down to hold the nuts in place, so some of the TNuts could rock a little on the other, loose side. The CA seeps under and glues it tight. I'm using Bob Smith medium viscosity 15 second cure, but on the rough side of the masonite it cures very slowly, but it's solid after 10 minutes. Luckily I haven't glued any fingers together yet, but there's still one baffle left. I like the first wiff of CA, reminds me of happy days in my previous stress free hobby of model airplane building. But after a few minutes the smell gets old fast.

Also today I will drill 4 small holes in each of the 64 divider panels that go between each driver, holes to allow the hookup wires to pass through. Some of the panels need less holes, according to the wiring schematic, but the most holes any panel needs is 4, so I'm drilling 4 in all of them, then I'll fill the unused holes after the hookup is done. That's easier than gluing each divider panel in a "correct" position, and messing it up. Also allows changing the wiring schematic if I already messed that up but don't know it yet. :)  Since all the drivers move the same, in same volume chambers, there shouldn't be any air movement through the holes, but I'll seal them up anyway, and the wires through the holes. Once the holes are drilled I can start the sexy job of gluing up the boxes.

Edit: My wife wants me to finish these so she can hear what all this work is for. So I am motivated to show it off for my biggest fan and that should accelerate my progress. Just don't hold your breath!  :roll:

That is one phase I don't like thinking about, making sure the nuts stay in place. I have not had any experience to see how long CA will work with wood. Will you need a combo of CA and CL to prevent nuts from falling after decades would work or just CA alone?? Using any washers, on either side??

Cheers and keep up the good work Rich.

Steve
I have used CA since the 80s and never had a failure even after repeated speaker R&R.  I always use Baltic birch as one of the front baffle layers to get a final baffle thickness of at lease 1".  Considerably thicker baffles for larger drivers.  Normally I'll use 1/4" -1/2"MDF, Medex or tempered Masonite for the external layer just to make it easier to finish.

ALWAYS use machine screws at least as long as the baffle thickness and use a lock washer under the screw head on drivers bigger than 7 inches.

Small drivers I drill the screw holes 1 size under the tap drill size for the screw being used.  Run a tap through the hole.  The tap will it and compress the BB fibers which increases the fiber density.  Apply Scotch tape to one side of the hole and fill the hole with thin CA and let it penetrate the wood for a couple of minutes.  Which the CA out with a pipe cleaner and let it cure naturally for 30 minutes.  Remove the cello tape and then spray CA accelerator in the hole and wait 5 minutes.  Then re-tap the hole.  I use this method on drivers up to 8".  Like I said - no failures. 

Larger drivers I normall use threaded inserts, but these need to be installed before routing the driver holes.  Drill the smaller hole first, then counter bore for the threaded insert.  Install the threaded insert and then run the tap through from the insert side.  Here is where disaster can happen.  Here is where disaster an happen. Stand the baffle board on one side and slowly, carefully saturate the wood (MDF, whatever) with thinCA.  Some fill flow underneath the insert.  Let it cure and then re-tap one more time.

Bullet-proof.

Sounds like a lot of work, but after you do it a few times it is faster than one would think and is way quicker than having to fix a bad hole.

Offline richidoo

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Re: Line Arrays
« Reply #68 on: August 13, 2017, 03:49:31 PM »
I LUV John Inlow. Great site! I check it out often, and planning to build some of his horns. But I hadn't noticed that line array build technique. Very clever! Drivers' center to center distance needs to be as small as possible to keep lobing confined to the highest freqs. The farther drivers are from each other the farther away you must sit to not notice the lobing when standing and sitting.

PI Good idea about threading BB. Thin CA works good to make any wood into a strong "composite." FYI You can make your own CA accelerator from water saturated with baking soda.

I didn't think about preventing driver screws from backing out from vibration, so I'll have to use loctite red if necessary. Or move on to the aluminum baffle version sooner if it's a problem.

Offline richidoo

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Re: Line Arrays
« Reply #69 on: August 15, 2017, 03:05:49 PM »
Finally gluing up the boxes. Slow going but feels good to be making progress.

Offline richidoo

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Re: Line Arrays
« Reply #70 on: August 29, 2017, 05:39:20 PM »
Gettin rollin on these now.

1, 2. Gluing on the other back panel
3, 4. Install wiring
5. Test fitting the front baffle
6, 7. Gluing on the front baffle
8. Ready for the final 2 side panels

The side panels have a 45 chamfer cut on a table saw. They are 53 inches long and for some reason the chamfered edge is not straight. So when it fits up under the front baffle overhang it leaves a gap. All 8 side pieces are the same way. Tomorrow I will try to recut them, as there is enough extra meat to recut that edge, but I'm not sure why it happened. Will have to make extra careful saw setup.

Offline tmazz

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Re: Line Arrays
« Reply #71 on: September 01, 2017, 08:28:00 PM »
Wait a minute!!!!!!

Your wife is letting you glue together speaker cabinets on her kitchen counters???????    :shock: :shock: :shock:

That woman must be a saint.  [-o<
Remember, it's all about the music........

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Offline richidoo

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Re: Line Arrays
« Reply #72 on: September 01, 2017, 09:47:19 PM »
Yes, she certainly is!

My daughter's baking messes are much worse. At least my glue is sterile.  :-P

Offline BobM

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Re: Line Arrays
« Reply #73 on: September 02, 2017, 07:06:20 AM »
Are you going to take over the living room with these monsters or have you moved upstairs yet?
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Offline rollo

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Re: Line Arrays
« Reply #74 on: September 02, 2017, 09:21:03 AM »
Looking good professor. Getting close.


charles
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