[tminus]

This is a repost from the "building a new OB" thread. 

I've been wanting to do waveguides frnt and rear for OB's with fiberglass baffles.  It would be similar to this times two for the frnt and rear guides:

http://www.putfile.com/pic.php?img=4008408

The man who did these is truly skilled, however, glassing these shapes is not difficult.  The pic shows the baffle just after the sealer was sprayed.  The drivers would be sandwiched between the front and rear baffle cutouts and decoupled from both.  Then the area between the outer edges of the baffles could be filled in with some nice hardwood panels and filled with sand or what-have-you to add mass - or layered up MDF with a veneer applied.  Mine will be figure 8 shaped instead of the rectangles pictured.

The OB dispertion pattern is figure 8 shaped, which causes the lame sound off axis.  My intention for the wavequides both frnt and rear is to cause the figure 8 dispertion pattern to move closer together, or "overlap" - something closer to a double cardoid pattern.  This should produce the most benefit in the lower registers, but I think the midrange can benefit allot as well.  Guess I'll be finding out.....

Patrick

[JohninCR]

Patrick,

They'll make some great looking baffles, however, they won't create the dispersion effects you are thinking.  At any point where the front and rear waves have travelled the same distance they will net to zero.  In other words, if the front and back are identical, at the sides they net to zero.  The most you will accomplish is to prevent some of the higher frequencies from wrapping around the sides, effectively increasing the null at the sides.

[tminus]

I was thinking of making the front guide deeper than the back.  I don't know how to model any of this, so I guess it would all be cut n hope.  The shape is just jersey or some "stretchy" fabric stretched between the two baffle planes and then doped.

[gitarretyp]

You should head over the htguide's mission possible forum. They're working on a dipole design with a waveguided tweeter.