Open Baffle Line Array

[24kilo]

Well here's my design for my open baffle line array The drivers are here, the wood is cut, so I’m getting to the nitty gritty. All the specs are in the pic.
The question I have is should I put acoustic foam on the backside of the baffle and should I put a cap on top or leave it open, I’ve seen Both ways. Any suggestions?

[Audiophilenoob]

I would have used around 2x the amount of tweeters

[DIY_newbie]

Originally posted by Audiophilenoob
I would have used around 2x the amount of tweeters

Ignore Noob's criticism, it looks like a nice way to try out open baffle line arrays. I bought 72 of those little square mylar domes for a similary project. I'll get around to it some day, keep us posted on how it goes...

--Chris

[Audiophilenoob]

Originally posted by DIY_newbie


Ignore Noob's criticism,

i was simply a suggestion


anyway... I would try it with the foam on the backside and see if you like it.... you might or might not

I would also put a cap on the top... to make it have dispersion up like it has down from the rear wave... (the floor will be the dispersion down area).

maybe make it removable in case you don't like it

[mazeroth]

Don't consider it criticism. I would have used at least 3x the amount of tweeters. You want the tweeter length to be as close to the woofer length as you can get.

Also, if that 8" is going to be open baffle as well, you might want to use another one.

[AJinFLA]

Ya, the bass might be a little weak with that single 8 OB.
Why not go on an insane spending binge and get one or (gasp) two of these

http://www.partsexpress.com/pe/showd...number=299-138

Sure, you would have to redo your fancy drawing and make it taller, but hey, you might end up with something resembling bass

cheers,

AJ

[ultrachrome]

Originally posted by 24kilo
Well here's my design for my open baffle line array The drivers are here, the wood is cut, so I’m getting to the nitty gritty. All the specs are in the pic.
The question I have is should I put acoustic foam on the backside of the baffle and should I put a cap on top or leave it open, I’ve seen Both ways. Any suggestions?

I tried lining the back of mine with foam and could not hear nor measure a difference.

Covering the front baffle with wool felt would help tame diffraction.

I agree with those above about the woofer. It's going to have a really hard time keeping up with the efficiency of the array. Dipole cancellation deals the hardest blow to the woofers and the combined efficiency of the NSBs is going to widen the gap even more. You should really consider using more and/or larger woofers.

How low will those NSBs play? Maybe ditch the woofers all together and just use a monopole sub to fill the gap.

What are you doing for a crossover?

[johninCR]

The line is too short to be much more than a nice big array for nearfield listening like desktop computer speakers. You'll probably want to even wire those tweeters in a bessel alignment if you are going to go with that few.

[24kilo]

Originally posted by johninCR
The line is too short to be much more than a nice big array for nearfield listening like desktop computer speakers. You'll probably want to even wire those tweeters in a bessel alignment if you are going to go with that few.

Computer Speakers?
First, This is not the first set of speakers I’ve built, To date 4way Tlines, Folded Voights{which I’m using now. They’re 3 ½ way diy 12db XO’s] and tub sub with 4 satellites. Also I have a Associates Degree in Electronics was a Tech for 12yrs {radar tech to component} before becoming a tool maker (High Class machinist 16years).
Now these Lines are 2way, Woofer and 4”s in series Parallel thus the 5k cross to the Tweets The Woof is there just to enhance the Bottom end, Not to be the main low end driver. I have 200watt sub for that.

[johninCR]

Almost 53pounds,

I wasn't knocking you or your design. I really like OB line arrays. Something you haven't really considered the impact of in your planning is the line length. To me this is a much more critical factor than driver spacing.

You essentially have a 1 meter array of your main drivers. With such a short line your resulting speaker will change tonality depending upon the listening distance. This is because it will act like an array above certain frequencies (spl -3db per doubling of distance) and act like a point source (-6db per dist X 2 ) below that nearfield/farfield transition point. With a 1 meter line length and a 2-4 meter typical listening distance this is going to occur in the 1-2khz range.

BTW, small OB arrays make great desktop speakers.