anyone out there???....
if I'm wasting my time typing this stuff and posting here I think I'll stop. LMK if anyone is watching because I won't keep wasting my time if not.
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After spending the last 30 minutes modeling on Edge, the one thing I’ve found is that as long as the baffle is of decent size in some dimension, the low end response isn’t hugely effected.
Take the below two pictures for example. Starting with the outer dimensions of 31.5x48 inches, I’ve drawn a standard square (picture 2 & 3) and a more complex shape (picture 1).
I’ve shown the response of the woofer location (bottom) and the fullrange at the top.
***Note: In the simulation you can only choose a single size for modeling multiple woofers. I’ve verified that modeling the location/size of the woofer as a smaller 8 inch driver is essentially the same below 200hz. Therefore, I’ve modeled the 15 in driver as an 8 inch so that I can model both drivers together. If you’re going to do the same, I ask that you verify the smaller size driver will effectively simulate the larger size up to the point at which you plan to cross it over. If I were crossing higher than 200hz, this would not have worked well at all.***
Note the difference in response at 30hz for both baffle shapes is not terribly out of sync, whereas the hump at 200hz is brought down a bit with the ‘coffin’ design. I think I almost prefer this design as it lends itself to a good low end response, without a peaky top end, which serves me no purpose as I’m crossing quite a bit below 200hz anyway.
I’ve also removed the data above 2000hz as it’s essentially the same in the grand scheme of things.
The pictures below correspond with the graphs shown overlayed.
Curve 1, Picture 1 = Coffin Shape
Curve 2, Picture 2 = Rectangle with offset full range at the top
Curve 3, Picture 3 = Current Rectangular design (the piece I made yesterday)
The coffin shape was chosen somewhat arbitrarily to show the differences in a complex shape having smaller woofer-to-edge parameters. The fullrange driver offset in the coffin shape is a ‘best case’, which saves me from cluttering up the thread with needless designs.
At 30hz, the coffin shape is about 2dB off my current rectangular shape. At 200hz the difference is 1.5dB.
So, what does this mean? It means, simply, that the large distance between the edge of the baffle and the woofer is important, though not as immensely as I had though. Also, it shows that a more subtle phase transition is attainable with a design like this as it allows me to make the fullrange driver’s baffle area smaller, while still giving large surface area to the woofer. Is this the final design I’m going with? Heck no. The coffin is ugly. But, for illustration purposes, it serves well. Also, I can base further designs off this, knowing I’m able to live with this kind of compromise.
I’m doing a lot of this work so that the design is at least thought out to some degree. However, the benefit of the DSP will likely wind up playing more of a role than the design itself in regards to the low end response. Sometimes I feel like I may be putting the trailer before the horse, given my potential use of DSP.
I’m curious to see how my modeled results in picture #3 compare to the actual results of this design I built yesterday.
Aaaaannndddd….
FTMFW!
MathCad Computer Models : Upgraded Versions
$25 fee, but access to some AWESOME mathcad programs. Very detailed, too, if you check out his sample worksheets (ie:
Full Range + Woofer OB worksheet). I use mathcad regularly at work so I'm already familiar with the program.
I'll have to sell some things, lol... me has no monies.
