Foam disc phase plug extension

High power and fidelity from an easy to build cabinet.
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himhimself
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Joined: Fri Nov 13, 2015 9:34 pm
Location: Bloomington IN

Foam disc phase plug extension

#1 Post by himhimself » Sun Jun 02, 2019 1:47 pm

I'm guessing (and hoping) that with the phase plug extension, it isn't critical to be perfect. I've cut about 4x as many plugs as I need trying to get clean, round discs out of the extruded foam insulation pieces I have, and am struggling to get anything that looks nice. It will obviously never be seen, so does it matter that the edges are not nice and straight? I have a few that are pretty close to perfect circles, but the edges are just ugly!
2xT30 (20", 3012lf)
4xOtop Jarray

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Bill Fitzmaurice
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Re: Foam disc phase plug extension

#2 Post by Bill Fitzmaurice » Sun Jun 02, 2019 1:57 pm

In this case pretty isn't necessary. The reason for the extension is to reduce the volume of the chamber created by the space between the cone and the plug, so close enough is good enough.

himhimself
Posts: 276
Joined: Fri Nov 13, 2015 9:34 pm
Location: Bloomington IN

Re: Foam disc phase plug extension

#3 Post by himhimself » Sun Jun 02, 2019 3:42 pm

Thanks Bill, moving ahead now, ugly but functional! Once again, not only is it great having the collective knowledge of this community, but timely answers from the designer himself. So glad I discovered BFM :clap:
2xT30 (20", 3012lf)
4xOtop Jarray

Bruce Weldy
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Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Foam disc phase plug extension

#4 Post by Bruce Weldy » Sun Jun 02, 2019 4:29 pm

I cut my phase plug discs to approximate size, then eased em up to the sander and kept turning them to get 'em perfectly round.
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6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

himhimself
Posts: 276
Joined: Fri Nov 13, 2015 9:34 pm
Location: Bloomington IN

Re: Foam disc phase plug extension

#5 Post by himhimself » Sun Jun 02, 2019 6:52 pm

Nice, Bruce. I didn't realize that stuff sands as well as it does. I smoothed mine out a little bit on my belt sander so they look a little better than before.
2xT30 (20", 3012lf)
4xOtop Jarray

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