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Discussion Starter · #1 ·
OK, I'm finally getting around to making a home theater kit I've had sitting around forever - and I'm confused!

Every build I've seen done of these speakers (Audax DIY Home Theater - designed by Joe D'Appolito) has all the drivers recessed, but his plans only show the AP130Z0 driver (the center channel mid-bass driver) as being recessed, all the other drivers are shown as being mounted flush on the face of the front baffle without being recessed.

Who am I to argue with or change a design by Joe D'Appolito?

Or does it not matter?

If I should recess them all as every build of the speakers I've ever seen has done, how do I determine how deep to recess them?

I'll really appreciate any comments at all on this, these are the first speakers I've ever built and I'm paranoid about messing them up!

Thanks!

(I'm attaching a sample picture and the plans to illustrate what I'm talking about)

Barrett
 

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The effect of recessing on the sound is minimal. It has no effect on the midbasses, other than looking nice. The effect on the tweeter, where the midbass frames might cause diffraction of the tweeter output, is slight. That's because in the lower end of the tweeter output the wavelengths are too long to be affected by the midbass frames, while in the upper end the tweeter radiation pattern is shrinking, and might not hit the midbass frames at all. The argument can even be made that not recessing the midbasses places their acoustic centers closer to that of the tweeter, for better time align. In any event it's really a cosmetic issue more than anything else. Where diffraction is concerned rendering the baffle non-reflective with foam or felt will have a far greater impact on the sound.
 

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Discussion Starter · #3 ·
The effect of recessing on the sound is minimal. It has no effect on the midbasses, other than looking nice. The effect on the tweeter, where the midbass frames might cause diffraction of the tweeter output, is slight. That's because in the lower end of the tweeter output the wavelengths are too long to be affected by the midbass frames, while in the upper end the tweeter radiation pattern is shrinking, and might not hit the midbass frames at all. The argument can even be made that not recessing the midbasses places their acoustic centers closer to that of the tweeter, for better time align. In any event it's really a cosmetic issue more than anything else. Where diffraction is concerned rendering the baffle non-reflective with foam or felt will have a far greater impact on the sound.
Thanks so much for your post Bill, knowing that it's not a huge difference either way is reassuring. I thought there was something I'd missed, given that he shows just the one driver recessed.
 

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That's really bad advice. While it's true that the woofers are less effected by the effects of surface mounting, it definitely makes a noticeable difference to the tweeters response. Depending on where the crossover is you could have a peak or dip of several db that was not accounted for in the design. You also could not just surface mount the woofer and flush mount the tweeter unless it was designed that way (not saying you would) as that changes the z-axis, which could throw the drivers out of alignment through the crossover.

edit: basically however it was designed is what you should do
 

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Thanks so much for your post Bill, knowing that it's not a huge difference either way is reassuring. I thought there was something I'd missed, given that he shows just the one driver recessed.
Joe is a pragmatist, but also a realist. Where his own speakers are concerned, and with most of his DIY designs, he tends not to bother adding some details that he knows aren't important. But where commercial designs are concerned he knows that some buyers will insist upon certain features being incorporated, whether they really matter or not, so he puts them in. In this case a dB or two of deviation here and there might seem significant, but it pales in comparison to all of the other response variations that result when you put the speaker in a room.
 
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