Posted by Duke [ 208.98.184.23 ] on March 03, 2008 at 07:43:38:
In Reply to: Re: Attending RMAF 2008 & Jazz Module posted by ttan98 on March 02, 2008 at 18:37:32:
Okay, I think the Parts Express round horns use a screw-on driver mounting system, so you'll need to get a pair of the Selenium adaptors for your bolt-on DE250s.
The PE round horn (or waveguide) has a 75-degree pattern. The 10" Beyma woofer probably has a 90 degree pattern in your projected crossover region, which is close enough in my opinion. I suggest listening to round horns from about ten to twenty degrees off-axis, as they tend to be smoother off-axis than on-axis. I like to use a lot of toe-in, such that the horn axes criss-cross in front of the listening position, as for one thing this gives decent tonal balance and soundstaging across a very wide sweet spot.
In my opinion, the weakness of the PE waveguides are the screw-on mounting system. I think that the resulting "snout" between driver exit and waveguide flare is a source of coloration, this based on measurements and listening. The DDS waveguide doesn't have it, nor do the 18 Sound elliptical horns (which are probably the next best thing).
As for cabinet damping, I presume you mean stuffing inside the cabinet. That's traditionally done by trial and error. Put the two boxes side-by-side, with more stuffing in one box and less in the other. Switch back and forth and compare, and then adjust the suffing quantity. I just use Polyfill from a fabric store.
For damping the cabinet walls, I use a technique called "constrained layer damping". Basically, you use a glue that stays soft to bond slabs of plywood to the inside of the enclosure. My source for the glue was North Creek Music Systems, but they have stopped selling it.
I have no experience with the DCX active crossover, but if it works well you might want to stick with it. The high-pass filter I'm using on the DDS waveguide is pretty complicated and took me a long time even with some fancy measuring equipment.
Best wishes,
Duke
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