Roundover vs. Chamfer - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 7 Old 08-08-2006, 01:35 AM - Thread Starter
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As the title implies, I'm wondering if there is a particular reason why I'm seeing all DIY'ers put roundovers on baffle edges rather than chamfers. Is it some sort of widespread aesthetic preference or do they actually work better for baffle step?
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post #2 of 7 Old 08-08-2006, 01:44 AM
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Quote:
Originally Posted by ChaoticKinesis
As the title implies, I'm wondering if there is a particular reason why I'm seeing all DIY'ers put roundovers on baffle edges rather than chamfers. Is it some sort of widespread aesthetic preference or do they actually work better for baffle step?
For the size roundovers you generally see, there is practically no effect, roundovers can help if the roundover radius is comparible to the wavelength, most made with router bits are not, so have little effect around baffle step frequencies.
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post #3 of 7 Old 08-08-2006, 01:50 AM - Thread Starter
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"Comparable to the wavelength" how? I don't see how the radius can be anywhere near comparable to the baffle width. Assuming an 8" baffle width which, according to an equation I don't recall, gives an f3 of 570 hz, define "comparable."
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post #4 of 7 Old 08-08-2006, 02:13 AM
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wavelength, meaning length of the wave... Sound travels at roughly 340 meters a second (does vary with temperature, humidity and atmospheric pressure a bit) and Hz refers to cycles per second. Therefore For a given distance, the corresponding frequency can be calculated like so:

340/x

where x is the length in meters, therefore for a 20mm roundover

340 / 0.020 = 17 000hz

you can do this in imperial:

13560/x

where x is in inches.


I believe the equation you are refering to was discovered empirically and used to find the -3db point, not the point at which baffle step effects first start having an effect (which happens at around a half wavelength of the baffle width (in this case 3.4khz, these results can be confirmed with modeling software such as the edge)
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post #5 of 7 Old 08-08-2006, 08:35 AM
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I'm seeing all DIY'ers put roundovers on baffle edges rather than chamfers.

It's a monkey see monkey do thing. Not all DIY'ers use roundovers or chamfers on
loudspeaker design. Not having it doesn't imply the design is a failure either. Alot
of loudspeaker designs try to solve problems, some can be measured and heard,
some can be measured and not heard, some problems don't exist but they find solutions
to fix it. lol



The storm was gone, but dark clouds still hung around
The perfect setting for things to come......

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post #6 of 7 Old 08-08-2006, 12:32 PM - Thread Starter
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Quote:
Originally Posted by thylantyr
It's a monkey see monkey do thing.
I had assumed that was the case but just wanted to be certain.

Regarding them not having any effect on sound quality: I'm wondering if this is the reason why I sometimes see a maximum roundover to use on a certain design. Because anything more would then actually begin affecting the frequency response in a way that had not been accounted for in the crossover? Or is all that still irrelevant?
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post #7 of 7 Old 08-08-2006, 03:43 PM
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If following a plan of directions with a DIY kit, there could be a maximum roundover imposed because of the thickness of the material (MDF) called for in the plans. There might also be some compromise to the integrity of the glued joint. Sometimes cleats are glued along the edges when a large (like 3/4") roundover is used, for more glueing surface area.

Sometimes you just learn things from someone you've come to admire for their knowledge in the field. One such person told me to use a roundover instead of a chamfer for best acoustics...so I take his word for it without having to know the intricate details. Another person told me that he wished he had used a roundover instead of chamfering the edges because he found it difficult to wrap the veneer.

There is good info in http://www.the12volt.com/installbay/...60&PN=70&TPN=1 on the subject. In it, I was asking about offsetting drivers...
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