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Old 28th January 2013, 11:53 PM   #41
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G'day Dumbledog,

The BIB has a very narrow baffle relative to it's height. Using the perimeter method in the calculator results in a block size that is too big for the width of the speaker.
For example, a baffle 180cm high x 25cm wide results in a block size of 4cm x 2cm - which means that the EnABL pattern would take up a total 16cm of the 25cm baffle width!

When I first began exploring EnABL for baffles I sought advice from BudP on this and he suggested using 4 x baffle width.
For a 25cm wide baffle, Bud's method gives us a block size of about 1cm x 0.5cm - much better.

Cheers,

Alex
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Old 29th January 2013, 12:27 AM   #42
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Thanks for the reply. I did the 4x baffle width and used standard electrical tape for the blocks. Preliminary results are interesting... The speakers I enabled are some crappy old ones, but the difference was noticeable. The sound stage seemed to shift and on the one side I enabled seemed to be less boxy. The sound came from that side, but not from the speaker so much. I'm building some of my own speakers (the WIBAQ) so ill enabl those for sure.
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Old 29th January 2013, 01:24 AM   #43
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Welcome to the joys of EnABL - there's no going back now!
When you treat the other side, the sound will shift back together again, but will be so much better. Keep posting your impressions as you go.

For some more mind blowing stuff, try doing all external edges, then run a pattern vertically up the middle of both sides, then continue it across the top.
Are they ported speakers?

Cheers,

Alex
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Old 29th January 2013, 01:57 AM   #44
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They are three way ported speakers: "Acoustic Response Seres 707" white van specials (free to me). I'm hesitant to play around too much with the enabl since these speakers are not going to be around for much longer. I think I will continue enabling the one speaker (port, sides, etc) to see how different I can make it, and if its a good change, apply that knowledge to my custom speakers which I will be hopefully starting shortly. I'm thinking the change when enabling a high quality speaker will be better than my current beaters.
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Old 29th January 2013, 02:10 AM   #45
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OK, in that case I'd recommend doing the port next. Minimal effort and huge return.
Port EnABL cleans up the bass but surprisingly effects the midrange as well (assuming the midrange driver occupies the same part of the box that the port does).

Cheers,

Alex
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Old 29th January 2013, 02:28 AM   #46
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I'll give the port a try then. The midrange is sealed, so no real benefit there. The bass is pretty sloppy anyway so it will be interesting to see the effects
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Old 29th January 2013, 06:40 PM   #47
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Hi Alex,
Thank you for getting back to me.
I have a few questions:

I've read through the thread and looked at the diagrams and know what to do with the front bottom and back internal panels.

What about the side panels?
(they are wider and will fit more than 18 block pairs)
Do we calculate a new series of larger block pairs for these?
I am also (as it happens) building a BIB so what do we do where the dividing panel intersects the block pair? Give it one block pair width breathing space?
Do we treat the two triangles as separate shapes? (and if that is the case could we use the pattern we have for the other panels even though this would leave us with more than 18 block pairs at the base?)
Or finally do we do nothing with it?

Another question: I am thinking of gluing thin balsa or other wood to the exterior baffle.
Can I varnish and put polyurethane over it or does a slicker finish minimize the effect?

Thank you,
-andré-
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Old 29th January 2013, 07:07 PM   #48
B00B00 is offline B00B00  Canada
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Just drew up some blocks and was scratching my head, reread your comment on Bib baffle width and it now makes sense (sort'of). My baffle is 22.5cm by 191.25 (internally) However, I plug in 4x the baffle width and it gives me even larger block pairs??? (Originally it gives me 4.75*2.375 but that is a rather large block and there is no way I'll get 18 of them in that width) I'm obviously doing something backwards.
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Old 30th January 2013, 02:52 AM   #49
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G'day andré,

Thanks for your questions. I'll try and clarify things for you and others reading this.

The 18 block pairs is absolutely critical when treating a driver (or circular baffles)
In the case of oval shapes and randomly shaped (curved or non-square) baffles, measure the perimeter and use 18 block pairs.

For rectangular baffles we use 4 times baffle width and the 18 block pairs to calculate the appropriate block size.

So, a width of 22.5cm will give a perimeter of 90cm and at 18 block pairs gives a block size of 1cm x 0.5cm.
The actual number of block pairs needed usually exceeds 18.

For side panels in a BIB I would use the same size blocks that you used for the other internal panels.
Run the patterns horizontally across the entire panel leaving a gap of one block width from where the front and back panel will attach to the sides. Also allow a gap of one block width on either side of where the dividing panel meets the sides. The pattern may look a bit untidy where it meets the dividing panel, but it won't affect the performance.

Thin balsa wood should be fine for the baffle. Use thin coats when applying the varnish and polyurethane to keep the edges of the balsa wood blocks as square as possible ie. you want the sound waves to be hitting a perpendicular edge on the blocks rather than a slope made from overly thick paint.

For the other exterior edges, and the vertical pattern down the middle of the side panels and back panel, you could use the balsa wood as well. Alternatively, you could finish painting the cabinet and apply clear contact paper (the stuff you use to cover shelves). This gives you the sonic benefit along with being almost invisible.

Hmmm, as another alternative you could also finish the cabinets with polyurethane as planned. Then use blue painters tape to lay out a template of the pattern and then paint in the blocks with polyurethane. I've had this idea for some time but not had the opportunity to try it.

NOTE:
Do take the time to plan the position of the edge patterns on the baffle and external edges!
Look carefully at the pattern in the corners of the baffle (see the pictures at the beginning of the thread).
Lining up the pattern like this will make it visually attractive as well as functional.

That's enough ramble for now, hope it helps.

Cheers,

Alex
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Old 30th January 2013, 02:23 PM   #50
B00B00 is offline B00B00  Canada
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Ah...
Thanks for clearing that up Alex,

I was taking the perimeter of each baffle...
Oops.
At 1cm * 0.5cm the pattern will not fit exactly into 22.5 cm, if I leave a fraction more or a fraction less space between the pattern and the edge, it isn't the end of the world I gather. (A fraction more being better?)

Also do I leave a space of 1x or 2x at the opening or leading edge of the baffle?

Pics of last night's progress...
Click the image to open in full size.
Going to plasticize it, cut out the squares and use a putty knife and plaster to apply it.
At least that is the plan.
We'll see how well it works in reality.

My biggest concern is to get the pattern flush with the material and not have it move in order to keep the edges crisp.
May wet it slightly with a spray bottle first to help the sheet stick. Could also tape it in place but that won't keep the center stuck to the surface.

The simplest way to make the pattern mind you would just be to block it out on graph paper and then plasticize it. The light bulb came on after I had painstakingly measured everything out. Haha

Will let you know how it went.
-andré-
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