# Nat P tower build question



## steve1616 (Apr 6, 2009)

I am getting ready to cut my first sheets of MDF tomorrow. I am going to build the Nat P towers, and have a question about the front baffle. Everyone in the tower builds seems to double up the 3/4" MDF for the upper part of the front baffle. See links below

http://www.htguide.com/forum/showthread.php4?t=21373

and 

http://www.htguide.com/forum/showthread.php4?t=19596

Is this really necessary? I don't mind doing it if it helps, but I would think that it would cause more problems than it would help. It has to change they way that air is pushed on the backside of the mid woofers. Some people chamfer the back piece to help this, but if they are doing this, than what is the point. One piece of 3/4" MDF should be more than sufficient for screwing in the speakers.


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## 1Michael (Nov 2, 2006)

steve1616 said:


> Everyone in the tower builds seems to double up the 3/4" MDF for the upper part of the front baffle. Is this really necessary?


Yes. If all of us are doing it, then it might be a good idea:T Its not just the upper part...double the entire baffle.


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## steve1616 (Apr 6, 2009)

Michael,

Thanks for the advise. I will double the entire baffle. Would you chamfer the backsdie for airflow on the mid-woofer?


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## fbov (Aug 28, 2008)

steve1616 said:


> I am getting ready to cut my first sheets of MDF tomorrow. I am going to build the Nat P towers, and have a question about the front baffle. Everyone in the tower builds seems to double up the 3/4" MDF for the upper part of the front baffle. ...Is this really necessary? ...


Best Practices are not mandatory, they just work out better. 

You'll note that the designer used an off-the-shelf box with a single thickness baffle, but added reinforcement around the tweeter. The 22x9 baffle of the bookshelf is stiffer than the 42x9 baffle of the tower, so the latter must be thicker for equal stiffness. Some folks like the look of a hardwood baffle (myself included), stablized by bonding to MDF. 

As to mounting, if you flush-mount the drivers (6mm recess), that leaves only 1/2" of MDF for your screws. It's all in how robustly you want to build. I leave my hardwood baffles as close to their native 4/4 thickness partly for that reason. 

On the back side, yes, chamfer the woofer openings on the back side of the front panel and enlarge the driver cut outs on the reinforcing panel to meet the chamfer. You will get excellent bass extension from these little 180's in a big box. 

Have fun,
Frank


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## steve1616 (Apr 6, 2009)

Would you chamfer just a little so that the screws can still bite in all the way through both pieces of MDF?


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## 1Michael (Nov 2, 2006)

Pre drill your holes, then do not chamfer the area around the holes. Or slightly angle the screws to get more of a bite.


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## steve1616 (Apr 6, 2009)

Thanks for the advice on the screws. I noticed yesterday that the cabinet plans from the link in my above post don't account for the extra baffle, but the guy building them says that he put in an extra baffle. I have already cut all the braces and sides so I was planning on just doubling the whole front baffle area with 3/4" MDF. A lot of the builds put the extra baffle on the inside of the cabinet, but is it ok just to double the front, and put it on the cabinet just like you you would with one piece. The only downfall I can think of is that I will have to finish the cabinet, and be able to hide the extra sheet of MDF.


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## domwilson (Oct 31, 2010)

If you are going to veneer the cabinets, why not just make the additional baffle out of the wood type that you plan on veneering the rest of the cabinet with?


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## domwilson (Oct 31, 2010)

Like these old Kenwood LS407b's?

http://gallery.audioreview.com/showphoto.php?photo=6358


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## steve1616 (Apr 6, 2009)

Maybe I should consider veneers, but I was planning on trying piano gloss black. I think I will be ok as long as I use some sandable primer or automotive putty in any bad spots.


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## domwilson (Oct 31, 2010)

I wonder how that piano black finish would look with a wood finished baffle? Just something to consider.


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## domwilson (Oct 31, 2010)

Check out this link...http://techtalk.parts-express.com/showthread.php?t=209789
Especially post #10

Here is his contact email... [email protected]


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## steve1616 (Apr 6, 2009)

Thank you for the email. I just sent him a message. I might have a few tries at this build. My brothers told me they each want a set of these speakers if the first set turns out good. If the guy you provided the email for can get me decent prices on some arch tops, I think these speakers will look great.


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## fbov (Aug 28, 2008)

If you plan on paint over MDF that has lots of end grain showing (as you'll have with a full-size front baffle), you may want to review Dave Pellegrene's work in that area:
http://techtalk.parts-express.com/showthread.php?t=214399
http://techtalk.parts-express.com/showthread.php?t=215464

I was promoting epoxy as the answer, and I've found it's not. 

HAve fun,
Frank


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