Driver Breathing Space

[Lindahl]

I'm mounting RS150-4s into two layers of MDF. I'm worried about the drivers getting enough breathing space, since the second layer almost closes airways between the motor and the frame. Due to access, I can't chamfer the back of the first layer. Instead, I'm going to pre-route larger holes in the first layer, before applying the second layer of the baffle. How large should I make these holes in the first layer to ensure plenty of breathing space? I'm thinking 1" larger than the frame (7" total)?

These won't be going very low, only to around 300 hz, or so, but I am aiming for high SPL.

[Jed]

That's about right.

[Lindahl]

Thanks. Should I do the same thing for this driver? I'm guessing not, since it is larger, and it's only working below 300hz...

https://www.madisound.com/catalog/product_info.php?products_id=1614

Cutting it a little close at 9" wide, so I'm not sure if I want to do a larger cutout and give up some rigidity, especially since we're stepping into bass territory.

[joecarrow]

That driver has a far more open basket. I think that just a chamfer and you would be in great shape. It wouldn't even have to be a very aggressive chamfer. Or am I missing way you're constructing this?

[Lindahl]

Yeah, I can't do a chamfer. I talked to the speaker's designer (Rick Craig) and he said that for it's frequencies, there isn't much to gain from giving the woofer more breathing room.

He confirmed what Jed confirmed, that a pre cutout of 7" for the RS150-4 would be plenty, as well as a good idea.