Roundovers: How much do you need?

[Spasticteapot]

Does anyone have any thoughts on the need for roundovers? One school of thought is that for a box of sufficiently narrow width, they're not really necessary; another dictates that they're required on the sides, while a third states that enormous roundovers along all four edges of the front of the loudspeaker are necessary to avoid baffle diffraction. Then there's the more extreme diffraction-control techniques, which include spherical enclosures and the use of waveguides. Does anyone have any thoughts on this issue?

[ZilchLab]

I would not consider the use of waveguides "extreme."

[We've previously discussed this, tho.... ]

http://techtalk.parts-express.com/sh...d.php?t=214805

[Spasticteapot]

Originally Posted by ZilchLab

I would not consider the use of waveguides "extreme."

[We've previously discussed this, tho.... ]

How important is a roundover on the top and bottom? - Techtalk at Parts-Express.com

D'oh!

Well, it's officially been a long day...

[Spasticteapot]

In any case, I'm still curious about the use of JBL-style elliptical waveguide. I'm considering shelling out a rather good-sized lump of cash for some milled metal enclosures, and I figure that if I'm putting a big lump of metal in a milling machine, I may as well go nuts.

I'm wondering if it's possible to simply duplicate JBL's waveguide as used on the LR6328.
JBL :: Product
This would be aesthetically pleasing, eliminate any problems with diffraction, and potentially reduce distortion in the midrange.

[Robh3606]

Why don't you just order a pair from JBL Pro?? All you need is a part number or where it's used to get them. Get the tweeters too so you don't have to worry about the transition to the waveguide.

Rob

[Spasticteapot]

Originally Posted by Robh3606

Why don't you just order a pair from JBL Pro?? All you need is a part number or where it's used to get them. Get the tweeters too so you don't have to worry about the transition to the waveguide.

Rob

I have a sneaky feeling my ScanSpeak 6600s are probably the better tweeter. Also, I'm hoping to have a seamless finish on the front of the speaker, and milling the waveguide into the surface would look a lot better than having a funny-shaped piece of plastic inserted. Furthermore, if I can get access to a CNC machine, it shouldn't be too difficult to mill the correct mounting points into the back of the waveguide so as to completely replace the faceplate of the 6600, allowing for an effective mounting solution.

Also, no screw holes.

Incidentally, as you seem to have one and I don't, could you tell me the depth of the waveguide?

[Loren42]

2" radius is the minimum for any meaningful diffraction control.

You need to do all four sides of the baffle.

[skeptic43]

Originally Posted by Loren42

2" radius is the minimum for any meaningful diffraction control.

You need to do all four sides of the baffle.

Supporting data, references??

[Robh3606]

and milling the waveguide into the surface would look a lot better than having a funny-shaped piece of plastic inserted.

They are cast aluminum. You are going to go through the expense and time of generating a unproven waveguide in CAD and then importing it and going through a machine program conversion from the CAD file. Have fun.

I have a sneaky feeling my ScanSpeak 6600s are probably the better tweeter.

Why??

Incidentally, as you seem to have one and I don't, could you tell me the depth of the waveguide?

They are a inch deep but without the profile it's meaningless.

Rob

[Loren42]

Originally Posted by skeptic43

Supporting data, references??

Vance Dickason's The Loudspeaker Cookbook.