Extreme BIB cabinet EnABL

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Seeing as I will be coating the entire interior surface of the speaker I picked up some acrylic floor wax. (The small bottles weren't going to cut it) A quick spray of polyurethane in a can... (the plaster rectangles might not take to kindly to being slathered in floor polish.) and we should be off to the races. :) This is the same stuff made by Johnson that the guys use on the model airplane forums.
An externally hosted image should be here but it was not working when we last tested it.

Have started assembling... :D
 

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Honestly, I don't know Alex.

Many years ago ,when I contacted Micro Scale about buying quantities they indicated that the Gloss was an industrial strength acrylic floor wax, that they purchased in 55 gallon drums. I did not ask who made it at the time.

They are more closed mouth about it now. There has been a change in chemistry, about 10 years ago. I still have some of the earlier material and of course some of the current also. When I used a lot of the material, the earlier product sounded slightly better and seemed physically more flexible.

To find out, all you really need are a pair of silk dome tweeters, as cheap as possible.

Bud
 
Silk dome tweeters are very susceptible to EnABL and Micro Gloss. A stiffer material will raise output and may introduce obvious FR peaks. A softer material does less damage.. So, if the material under question matches the Micro Scale Gloss in performance change, then it is for all intents the same material. Easier and cheaper than messing with wider range drivers.

Bud
 
Hi Bud and Alex, just to say that the cabs are up and running...

In a word, *very* articulate... lots of low level information on recordings that I have never picked up before.
I posted pics here:
http://www.diyaudio.com/forums/full-range/66173-terry-cains-bib-why-does-work-does-anyone-have-those-fostex-craft-handbooks-523.html#post3405743

But this gives you a general idea of what the cab looked like before being sealed up.
An externally hosted image should be here but it was not working when we last tested it.


I will post listening impressions later.
Thank you for all of your sage advice.

Next on the list of things to do, enable the speaker and then the outer baffle.

Looking forward to what further tweaking will bring.
-andré-
 
Hi Alex, Thanks for getting back to me, you said in the other thread:

You could use the same block size for the outside of the enclosure. Or if you are obsessive like me you would calculate block size based on four times baffle width.


I'm a little unsure..
So if my front baffle is 29.2 cm wide I calculate 18 block pairs to fit into 4*29.2cm?

Thanks,
-andré-
 
G'day andré,

Yes. Your block size comes out at 1.298cm x 6.49cm.
For simplicity, I would round these down to 1.2cm x 0.6cm (or 1/2inch x 1/4inch).

Main thing to remember is to plan the layout of the blocks so you get it looking nice.
Centre the pattern on the top of the baffle, then run it down the sides always maintaining a block width gap from the edge.
Refer back to the pics in the first post to get an idea of how it would look.

Cheers,

Alex
 
Brilliant, Thanks Alex...
Going to make a template with the plexiglass and proceed in the same manner as I did for the inside panels except will use plastic wood (which is stainable) instead of plaster.

Once the pattern is down, I plan on staining the speakers and putting a coat of polyurethane on top.I'm guessing that I want a coat of acrylic floor wax on top of that as well.

-andré-
 
That should work.
Given that it's visible, I would suggest doing a test on some scrap to see how the colour of the stain effects the plastic wood. If you're happy with that then go for it.

A possible alternative to consider would be to see if polyurethane would work with the template to form the blocks. So, stain, polyurethane the speaker, poly blocks then floor polish. That would make the blocks more stealthy and if some blocks don't come out as clean as others it will be less noticeable.

Whichever method you go with, do a test on scrap just to be sure you get the look that is the most pleasing to you.

Cheers,

Alex
 
Well, my girlfriend heard the speakers over the weekend and was most impressed.
Was even willing to put up with the size given the spectacular sound.

Funnily enough... the block sizes on the template are 1.2cm * .6cm so that works out rather well. :) I'm not sure if the polyurethane would work with the template. I suppose I could spray it in on thin coats in order for it not to bleed but it would take forever. I'm not crazy about the pattern on the exterior of the baffle but function first, form follows. What about clear silicone? Hmmm... that might work for the first couple of passes but I could see it getting messy pretty quick. (Same thing with epoxy and I don't see it holding it's form...)

Going to sit and think a bit if I will use the plastic wood or not.
The clear silicone would work if I can keep the template clean but would mean I would apply it post stain.

-andré-
 
andre'

Please your girl friend even more. Ask her to take you to a "girls hobby store". There you will find clear acrylic 0.003 inch thick film with a stick and peel adhesive. It comes in rolls. Girls use it for shelf protection in kitchen cabinets. It is cheap. You can cut it with a paper cutter and snip the strips to size. You can then use a simple guide to apply these pieces in an EnABL pattern to the outer edge of your vertical baffle sides.

Then you can use the tap test to find the locations on the baffle for arcs that defeat the rest of the surface problems. a meter away you cannot see these pieces and you can take them off if you don't care for them. They will not harm the cabinet finish your girl friend will like you especially well for a while and may even volunteer to help out. IT really isn't even tedious to do because, if you play music softly while applying the blocks you can hear immediate changes.

Don't wreck the finish on your boxes please!

Bud
 
At my local Home Depot, they have rolls of thin cork with adhesive backing. Since cork is relatively soft, would this be a good idea for baffle enABL material, or should the material be hard plastic, like the 0.003 inch thick acrylic sheets from the craft store that Bud mentioned?

Also, 0.003 inch is only 0.75 mm. That is really, really thin. That's what's best to use? (Just making sure I got that right.)

I've been experimenting recently with wool felt on baffles, bought from Grainger. It's expensive, ugly, and I'm not sure it's always an actual improvement. But it is always different.
 
Haven't enABL'd anything per se, but I've treated whole baffle areas around [mid] tweeters with thin cork to good effect.

0.003" = 0.0762 mm, so really, really, really thin ;).

Industrial wool felt is very dense, so can be a bit of a reflector at some band of frequencies depending on thickness, quality. Good for damping floor standing speakers or similar vibrating devices. My long gone manual typewriter's pad does a good job of isolating my shelf mounted computer speaker system's little boom-box 'sub'.

GM
 
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