[tomlinmgt]

I have several 4’x4’ sheets of 1/2” BB sitting around and am about to build an x-Statik kit. Since the front baffle is doubled up, and the sealed enclosure has a good bit of bracing, would there be any issues with using the 1/2” BB?  Could the use of norez help deal with any potential resonance issues created by using ply rather than MDF?

Thanks
Michael

[S Clark]

I wouldn't use 1/2" sides or back.  Laminating to get 1" would be great, but it's going to throw off the cabinet width by 1/2 inch if you use the same internal brace size... might not matter much if you use a roundover bit all down the front.
No doubt it's worth making a few adjustments if the material is already on hand. 

[Hobbsmeerkat]

Well, the cabinet plans intend for the use of 3/4" MDF, so the you're probably going to have to double up the entire length, then a 3rd layer above the cabinet to match the 1.5" thickness.

And if you want to reduce resonance, you can use a product like Decidamp between the two main layers, since it also works as an adhesive, as well as an elastomer for constrained layer damping.
Then use regular wood glue on the upper, 3rd layer, & norez inside the cabinet.

I'd also made sure to probably use a 1/2", or larger, radius on the inner  back side of the front baffle for the woofers, to help compensate for the added thickness.

But keep in mind that if the remaining parts of the cabinets should also be made using 1" of plywood (using the Decidamp between the  doubled layers if still using the 1/2" plywood) and you'll have to make adjustments to the plan's given measurements, to make sure all parts match up.

[tomlinmgt]

Sounds like I should probably just stick with 3/4” MDF...but it would be nice to at least be able to use the BB ply for the front baffle rather than veneer over MDF...but since the front half of the baffle makes up the entire baffle for the lower drivers, I suppose 1/2” thickness isn’t going to be sufficient there. 

[Hobbsmeerkat]

For consistency & ease, 3/4" MDF will make building the cabinets easier, but the front baffle can still be easily be made with a double layer of BB plywood, and an extra 3rd layer for the upper portion, since 3 1/2" layers is the same as 2 3/4" layers.. with the only change being a slightly larger roundover for the internal woofers.

[tomlinmgt]

For consistency & ease, 3/4" MDF will make building the cabinets easier, but the front baffle can still be easily be made with a double layer of BB plywood, and an extra 3rd layer for the upper portion, since 3 1/2" layers is the same as 2 3/4" layers.. with the only change being a slightly larger roundover for the internal woofers.

This sounds like the most reasonable way to use up some of this 1/2” BB ply yet keep the build close to spec. Did I understand you correctly about using the Decidamp to laminate the two pieces that will make up the front baffle, and wood glue between the front baffle laminate and rear-upper piece of the front baffle? I see there are several different Decidamp products/formulas.  Which is appropriate for this application?

[Jonathon Janusz]

I looked at the plans, and since the back covers the edges of the side panels, it would only take adding 1/4" to the length of the very bottom base piece to use a doubled layer (1" total thickness) of your BB for the back without changing any of the major dimensions (internal dimensions and baffle width in particular).  I see what Scott is saying above, but if you only use your BB on the front and back and MDF for the middle parts, you wouldn't run in to the problem Scott brought up.  You should also be able to use a double thickness for the bottom most base piece if you're okay raising the total speaker height up 1/4" (which would go up if you put spikes on it anyway).

[tomlinmgt]

I looked at the plans, and since the back covers the edges of the side panels, it would only take adding 1/4" to the length of the very bottom base piece to use a doubled layer (1" total thickness) of your BB for the back without changing any of the major dimensions (internal dimensions and baffle width in particular).  I see what Scott is saying above, but if you only use your BB on the front and back and MDF for the middle parts, you wouldn't run in to the problem Scott brought up.  You should also be able to use a double thickness for the bottom most base piece if you're okay raising the total speaker height up 1/4" (which would go up if you put spikes on it anyway).

I like the idea of doubling up to make a 1” thick base. I’d prefer to have the more durable ply on the base than MDF anyway.

[Hobbsmeerkat]

This sounds like the most reasonable way to use up some of this 1/2” BB ply yet keep the build close to spec. Did I understand you correctly about using the Decidamp to laminate the two pieces that will make up the front baffle, and wood glue between the front baffle laminate and rear-upper piece of the front baffle? I see there are several different Decidamp products/formulas.  Which is appropriate for this application?

Correct, since the 1" baffle will run the full length, it would be the most useful position for Decidamp. It wouldn't be necessary for the upper/rear portion since its main goal is to help support the drivers.
The version best suited for this application would be the 2-part Decidamp "DC30" since it's specifically designed for use in constrained layer damping.

This video here does a pretty good job of explaining how CLD works, & the affect it has on resonance. (Starting around the 34 minute mark)
https://youtu.be/EEh01PX-q9I

[Captainhemo]

I'd do it all in the BB being you  have it on hand.
Do the enntire baffle 3 layers and make it    1/4"  wider on each side.  Then , do the  entire sealed section  in doiuble layer BB (1/4" wider on each side to keep internal volume the same) pick up some scrap MDF for the  3/4" internal bracing. Cabinet will be  1/4"  wider on each side to match baffle as well as  1/4"  deeper."

Cut   1" roiundover on the vertical edges of the  front  baffle  Also cut the 1"  roiundover on the rear of all woofer cutouts.  You'll end up with   the flat  surface of the  baffle being the same as adding  a .5"  r/o to the standard width baffle  ,you'll just have a larger  r/o which is not a bad thing  at all.  On top of that  the  sealed cabinet will be  1"  thick, again, this is a good thing.  Even with the  1"  sealed enclosure, I'd still recommend  lining it with no-rez.

Oooops,  that'd be  a  3/4" roundover on  vertical edges of front baffle to match original  baffle with  .5" roundovers

jay

[Hobbsmeerkat]

If you decide to go the all 1" route as Jay mentioned above, you can make better use of the Decidamp on all the doubled side & rear panels, as well as the front panel.

[tomlinmgt]

$190 for the smallest packaged quantity on that DC30. Ouch. Kinda defeats the purpose of trying to save money by using existing materials. Is there not a less expensive alternative for laminating two pieces of BB ply?  Isn’t there a  product called “green glue” that is used for this type of thing?

[Hobbsmeerkat]

That's a fair point, esp if cost is an issue.
But any typical wood glue and a few clamps/ weights should still work just fine. A slow curing might be better to allow for more time to spread out the glue evenly with a brush/roller before laminating them, & using norez will still help dampen the cabinets.

Looking at Green Glue, it definitely seems to be a similar product, and might work well in this case, esp since you'll likely only need 3-4 tubes for both kits. Though it recommends a "random" spreading pattern onto drywall, it'll probably be more ideal to make sure it's spread out into a thin coat for better adhesion, and more consistent results.