[Sandbakk]

Greetings from Norway.

One question: will a thickness of 9cm (3.5 ") on the baffle have a major impact on the sound of a single element open baffle construction?

Today I have a pair of Decware Big Betsy with the speaker element F15 from Lii Audio. Just for fun, and to test the difference, I have plans to build a pair of larger Open Baffles with F18 from Lii Audio. And in that connection I can buy a table top in solid oak 100cm wide, 250cm long and 9cm thick.

So the question is whether the thickness of 9 cm (3.5 ") will have a negative impact on the sound image in terms of diffraction, and possibly where the front of the woofer should be placed, in front of the hole, in the middle, or in the back?

Thanks

[FullRangeMan]

Greetings from Norway.

One question: will a thickness of 9cm (3.5 ") on the baffle have a major impact on the sound of a single element open baffle construction?

Today I have a pair of Decware Big Betsy with the speaker element F15 from Lii Audio. Just for fun, and to test the difference, I have plans to build a pair of larger Open Baffles with F18 from Lii Audio. And in that connection I can buy a table top in solid oak 100cm wide, 250cm long and 9cm thick.

So the question is whether the thickness of 9 cm (3.5 ") will have a negative impact on the sound image in terms of diffraction, and possibly where the front of the woofer should be placed, in front of the hole, in the middle, or in the back?

Thanks

90mm real wood seems impressive, for me I could prefer 30 to 40mm real wood.
Woofers near the floor have more bass than when placed on top of the baffle.
Personally I prefer front mounted with 30mm baffle.

[JLM]

Definitely front mount.  Thicker panels means more mass, always a good thing for loudspeaker construction.  In the case of O.B. it's a simple action/reaction phenomenon, plus the ever present flexing of the panel (thin/flat O.B. panels behave like diving boards).  And being heavier they'll be harder to tip over.   

[DannyBadorine]

I would definitely front mount the woofer, but since it's a single full range driver, it might be worth experimenting with it slightly recessed. But if you recess it further into the baffle then you are creating a waveguide for it which will certainly change the frequency response.
 I think a thick baffle is helpful in minimizing resonance and can help the speaker settle faster.  I experimented with a 1.5" baffle recently and it had a better waterfall chart than a .75" baffle.
I don't think the thickness of the baffle is a diffraction problem worse than a thin baffle, but you will want to bevel or round the edges.  You will also want to bevel and/or round the edges of the hole that the driver is mounted in.  Having a baffle that thick could really change the frequency response coming out the back if it is front mounted since it becomes a waveguide behind the driver.  9cm is a significant amount.  You will definitely want to do some test measurements and see what is happening in the back if it is traveling through 9cm of wood before it comes out.

[JohnR]

^ that. Although it is a large driver. I'm having trouble seeing how it's worth it.

[Poultrygeist]

I always front mount with foam tape between OB drivers and baffle. I get a stronger mount that way. I usually play at medium to low volumes and never encounter resonance from 3/4" MDF baffles.