Dave A Posted February 19, 2020 Share Posted February 19, 2020 Kirby and I were talking about MDF the other day. I took him outside to my flatbed trailer and showed him a piece of 3/4" baltic birch under the tongue jack where it has been for months in a very wet period and with freezing and thawing. There it sits stained but otherwise as good as new. No delamination no warping no rotting. You want strength in all ways and good acoustics BB is what I choose to use. Here in Nashville this is what the lumber yards tell me. MDF goes into car boom boxes and BB goes into speaker cabinets. They sell so much BB that even with the 9.75% tax a 60" x 60" x 25mm sheet costs $48.00 out the door. Music City has spoken and it's preference is BB. 1 Quote Link to comment Share on other sites More sharing options...
Pete H Posted February 19, 2020 Share Posted February 19, 2020 12 hours ago, Lbk said: What material did use, MDF - BB? 18mm baltic birch. I did use the mouth brace, but that's it. Quote Link to comment Share on other sites More sharing options...
Lbk Posted February 19, 2020 Author Share Posted February 19, 2020 (edited) 12 hours ago, Dave A said: Kirby and I were talking about MDF the other day. I took him outside to my flatbed trailer and showed him a piece of 3/4" baltic birch under the tongue jack where it has been for months in a very wet period and with freezing and thawing. There it sits stained but otherwise as good as new. No delamination no warping no rotting. You want strength in all ways and good acoustics BB is what I choose to use. Here in Nashville this is what the lumber yards tell me. MDF goes into car boom boxes and BB goes into speaker cabinets. They sell so much BB that even with the 9.75% tax a 60" x 60" x 25mm sheet costs $48.00 out the door. Music City has spoken and it's preference is BB. Agreed but this time of year money is tight and time is not. Got a good deal on some 23/32 inch plywood and thought I would give one a shoot. If it does not work out I will build another in a month using BB. I'am anxious to hear a folded horn sub. Edited February 19, 2020 by Lbk Quote Link to comment Share on other sites More sharing options...
Pete H Posted February 19, 2020 Share Posted February 19, 2020 Sorry, I misspoke about braces, I did put some in. Went back and looked at the pics from the build. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 19, 2020 Share Posted February 19, 2020 15 hours ago, Lbk said: Carl do you remember how far the mouth brace is from front edge, looks to be about 6 inches? Thanks. No set dimension. You can run it out to the front edge if you want to or leave it shy. Quote Link to comment Share on other sites More sharing options...
HPower Posted February 19, 2020 Share Posted February 19, 2020 I braced my F20, it's not that much extra work. And it's not like you can go in after the fact and add them. 1 Quote Link to comment Share on other sites More sharing options...
jason str Posted February 19, 2020 Share Posted February 19, 2020 That front panel where the woofer is firing needs bracing the most, not one yet i have seen has bracing. Move the woofer 1-2" so the woofer is centered in the driver chamber, then you will have plenty of material to glue up that brace properly. Quote Link to comment Share on other sites More sharing options...
capo72 Posted February 19, 2020 Share Posted February 19, 2020 Has anyone tried moving the mouth of the horn to the adjacent face? The dimensions would work better for me if the mouth was moved to the panel opposite of the woofer access panel. I have seen some tapped horn subs with options for moving the mouth to different panels (Danley I believe). I have just not seen an F20 folded horn sub configured that way. It looks as though some expansion may be lost so I don't know if it's viable. Been looking at the Lil Wrecker as well. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 19, 2020 Share Posted February 19, 2020 1 hour ago, capo72 said: Been looking at the Lil Wrecker as well. I think it's about 9 cu ft bigger than the F-20. It's a load. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 19, 2020 Share Posted February 19, 2020 Leave the driver where the plans say it's supposed to be and brace like the picture above. You'll be fine. There's no vibration anywhere on the cabinet even when you're airing it out. Quote Link to comment Share on other sites More sharing options...
Lbk Posted February 20, 2020 Author Share Posted February 20, 2020 (edited) On 2/19/2020 at 3:03 PM, CECAA850 said: Leave the driver where the plans say it's supposed to be and brace like the picture above. You'll be fine. There's no vibration anywhere on the cabinet even when you're airing it out. I think that's good advice since this my first f 20 build. But would it help any if the brace next to sub was extended to run in front sub and connect to the mouth exit panel? Bad idea? Hpower I like the black finish on your sub, is that duratex? Edited February 21, 2020 by Lbk Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 20, 2020 Share Posted February 20, 2020 2 hours ago, Lbk said: I think that's good advice since this my first f 20 build. But would it help any if the brace next to sub was extended to run in front sub and connect to the mouth exit panel? Bad idea? Not sure what you mean. Are you talking about putting a brace in front of the driver? If so it isn't necessary. Quote Link to comment Share on other sites More sharing options...
HPower Posted February 20, 2020 Share Posted February 20, 2020 9 hours ago, Lbk said: I think that's good advice since this my first f 20 build. But would it help any if the brace next to sub was extended to run in front sub and connect to the mouth exit panel? Bad idea? Hpower I like the black finish on your sub, is that duratex? Yep, Duratex. Quote Link to comment Share on other sites More sharing options...
Lbk Posted February 20, 2020 Author Share Posted February 20, 2020 9 hours ago, CECAA850 said: Not sure what you mean. Are you talking about putting a brace in front of the driver? If so it isn't necessary. Yes in front of sub by extending the first brace. I will follow existing plans with above bracing, thanks! Quote Link to comment Share on other sites More sharing options...
Lbk Posted February 20, 2020 Author Share Posted February 20, 2020 1 hour ago, HPower said: Yep, Duratex. Do you remember how much you used? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 20, 2020 Share Posted February 20, 2020 Just now, Lbk said: Yes in front of sub by extending the first brace. I will follow existing plans with above bracing, thanks! Yes, no need to brace across the face of the driver. The driver baffle is close to adjacent panels on all 4 sides which provide support. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 20, 2020 Share Posted February 20, 2020 Just now, Lbk said: Do you remember how much you used? I'd estimate at least 2 quarts. Let's see what he says. Quote Link to comment Share on other sites More sharing options...
HPower Posted February 20, 2020 Share Posted February 20, 2020 6 minutes ago, CECAA850 said: I'd estimate at least 2 quarts. Let's see what he says. Hey Carl, He says, he can't remember but I bet your guess would be close. I would suggest buying 1 gallon, and a roller. If you keep the bucket sealed up good, your left over Duratex should last, ready for your next project. https://www.parts-express.com/acry-tech-duratex-black-1-gallon-roller-grade-speaker-cabinet-coating--260-101 https://www.parts-express.com/acry-tech-9-textured-roller-for-duratex--260-113 To get a slightly smoother finish, I usually mix a very small amount of water into the Duratex. Tips-for-Storing-DuraTexR.pdf Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 20, 2020 Share Posted February 20, 2020 6 minutes ago, HPower said: To get a slightly smoother finish Or just go over it with a long nap paint roller while it's still wet. Quote Link to comment Share on other sites More sharing options...
Lbk Posted February 20, 2020 Author Share Posted February 20, 2020 (edited) 40 minutes ago, HPower said: Hey Carl, He says, he can't remember but I bet your guess would be close. I would suggest buying 1 gallon, and a roller. If you keep the bucket sealed up good, your left over Duratex should last, ready for your next project. https://www.parts-express.com/acry-tech-duratex-black-1-gallon-roller-grade-speaker-cabinet-coating--260-101 https://www.parts-express.com/acry-tech-9-textured-roller-for-duratex--260-113 To get a slightly smoother finish, I usually mix a very small amount of water into the Duratex. Tips-for-Storing-DuraTexR.pdf 87.36 kB · 1 download Sub measures approx. 51square ft. According to PE one quart will cover 20 to 24 sq ft. So looks like a gallon to be safe. Edited February 20, 2020 by Lbk Quote Link to comment Share on other sites More sharing options...
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