Baffle Step on non-rectangular Baffles - diyAudio
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Old 2nd February 2009, 04:46 AM   #1
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Default Baffle Step on non-rectangular Baffles

Hi everyone,

Looking for insight as to how everyone plans for Baffle step if the baffle is not rectangular? If I take a design that works well with a certain size rectangular baffle, hold the volume, crossover, and port dimensions but change the shape of the cabinet, will there be significant changes in the response? Would it suffice to look at the layout, figure out the min and max dimensions (woofer to different edges of the face), and ensure that the new shape has a similar range and total surface area?

thanks!
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Old 2nd February 2009, 05:23 AM   #2
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Use a tool like the FRD Baffle Diffraction Calculator to compare the two baffle diffration profiles and see how much difference there is. This should tell you if XO changes are needed.

Regards,

Dennis
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Old 2nd February 2009, 05:37 AM   #3
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I've been contemplating a similar problem. Though admittedly in my case, it is all conceptual, as I'm not going to be in a position to build them for a long time.

In my case, the overall speaker is a tapering tower. The bottoms section is wide with sharply tapering or sloping sides; think trapezoid. The upper section is a standard 8" three-way, so it is also a trapezoid, but taller with very shallow slope to the sides.

So, how do I predetermine baffles step on a cabinet with sloping sides?

I figured if I ever build them, I would just test the upper section to determine where the baffle step was, then design the lower section as an 0.5-way to compensate at the correct frequency.

But, is there a way to pre-determine? Can the FDR Baffle Defraction Calculator deal with a cabinet with sloping sides or a trapezoidal front profile?

Steve/bluewizard
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Old 2nd February 2009, 05:38 AM   #4
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Quote:
Originally posted by djarchow
a tool like the FRD Baffle Diffraction Calculator
Edge

http://www.tolvan.com/edge/

dave
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Old 2nd February 2009, 03:09 PM   #5
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Thanks for the replies!

I took a quick look at the screen shots ... it doesn't seem either of these can handle complex curves. I am planning to make my next pair of speakers by laminating CNC cut layers of MDF. Here is an example of my construction proof-of-concept for a center channel

Can either of these handle a dxf import?

Is there some math that can be done based on some simplified theory or will I have to measure and tweak once the speakers have been constructed?

tks!
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Old 2nd February 2009, 03:24 PM   #6
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Neither of the tools can handle a dxf import. Remember that the baffle step is just one piece of the larger effects of diffraction. Any change from a predesigned XO's baffle may require a redesign of the XO to properly handle the new diffraction effects.

Witha baffle as uniqe as the one in your link, I would think a measurement and some extensive listening would be required to make sure what if any changes are needed.

Good luck,

Dennis
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Old 2nd February 2009, 05:38 PM   #7
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If you are going to place the cabinet in the same place as the centre, there are no tools that can take the shelf/TV/other componenets into consideration.

dave
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Old 2nd February 2009, 06:53 PM   #8
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Thanks guys!

When I asked my question, I was actually only thinking of the baffle step due to radiating into different space (half, 1/4 etc.)- not the effects of diffraction at the edges. Regardless, I guess I will just select a kit and listen/measure/tweak.

Also, I plan on adding a left and right before re-doing the center - so for the moment, the screen, shelves etc should come less into play.

tks!
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Old 2nd February 2009, 08:00 PM   #9
Ron E is offline Ron E  United States
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Quote:
Originally posted by BlueWizard
Can the FDR Baffle Defraction Calculator deal with a cabinet with sloping sides or a trapezoidal front profile?
Yes.

Quote:
Originally posted by jmacmythtv
When I asked my question, I was actually only thinking of the baffle step due to radiating into different space (half, 1/4 etc.)- not the effects of diffraction at the edges.
The 2pi-4pi transition is the same phenomena as the edges. If you calculate the effect of the edges, you get the 2pi-4pi transition.

These programs are very computation intensive and require a lot of simplifying assumptions to work properly in teh first place. Adding a complex curve probably wouldn't be much different from a roundover in a macro perspective.
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