OTop12 Build Thread

[miked]

I bought two Queen size toppers; they were out of King size. Figures. I'll save the receipt; maybe I"ll be able to return one. They are $20/ea + tax, you know.

Reflectors in. Not as much of a "drop-in fit' as I would've liked, but I knew some of my horn panels were off a little bit. Nothing liberal application of PL didnt' cure. I won't chop the horn panels tonight; I will wait until tomorrow to ensure the PL is set. Why rush it now?

[miked]

I don't remember reading about this in anyone else's OTop build thread, but thought I'd just put this out there.

All my panels' measurements are dead-on exact, per the plans. Though it is too bad I couldn't get the horn braces on correctly, but that's another story. Anway, last night I was just test fitting the sides and the back and I noticed that my back panels are too short both in height and width (absolutely USABLE, but not optimally sized). They measure 13 3/4" x 20 3/4", per the plans, but the space they must fill is 14.0" x 21.0". I guess this was probably an intentional design decision to leave a little wiggle room for the Backyard Bunglers out there. But now my rear panels will have a 1/8" gap all around. Not a huge deal as the back panel braces are 1" all around. No way I'm making 4 new panels, but if I would've caught this fact earlier, I'd have made my rear panels 13 7/8" x 20 7/8".

I guess it depends on your tools and your skill with them. I know for a fact that I suck with a handheld circular saw. If I had to cut the rear panels "by hand" I'd probably need that extra wiggle room. But with a table saw I'm accurate to a 32nd or better on a good day.

Thought it would be worthwhile to mention this, so those building these cabs could possibly know about it beforehand and possibly size their rear panels differently.

On a different note, I'm planning on installing the damping material in the "forward half" (forward of the baffle) before putting on the sides as this area is much easier to reach and get a staple gun in there w/o the sides on. Will save some grief and bad words later. I may even mask off the glue surfaces where the sides go and spray the mattress topper black. MUCH easier than trying to spray through the handle hole later on.

Referring to this area here, the back of the horn panel.

[DJPhatman]

Anway, last night I was just test fitting the sides and the back and I noticed that my back panels are too short both in height and width (absolutely USABLE, but not optimally sized). They measure 13 3/4" x 20 3/4", per the plans, but the space they must fill is 14.0" x 21.0". I guess this was probably an intentional design decision to leave a little wiggle room for the Backyard Bunglers out there. But now my rear panels will have a 1/8" gap all around. Not a huge deal as the back panel braces are 1" all around. No way I'm making 4 new panels, but if I would've caught this fact earlier, I'd have made my rear panels 13 7/8" x 20 7/8".

This design "flaw" is actually there to provide room for a finish. If this was to be a furniture quality finish, then I could understand the need for a smaller gap. But, using either a durable painted-on finish, such as Duratex, or carpeting, that gap will diminish quickly.

[miked]

Hmm. Didn't think about that. I guess Duratex could close that gap up a bit. Though I don't really see it taking up 1/8" of space all around. If I was using carpet, then the extra space would be a non-issue.

This is definitely a "user should consider this beforehand" issue, and I did not. If my back panels weren't already finished, I'd be making new ones. But they are done. Jack mounting plates, Speakon holes drilled and all mounting screw holes already predrilled and perfectly spaced...I'll just make sure to use lots of gasket tape.

[DJPhatman]

Though I don't really see it taking up 1/8" of space all around. If I was using carpet, then the extra space would be a non-issue.

It should take up about half the space. You don't want the back panel to be a friction fit, so a tiny gap is actually needed. A 1/32" of Duratex is easily two coats... x 4 edges (2 on the panel, 2 on the cabinet) and you've totally removed that gap.

[miked]

Thanks, DJPhatman.

Quick question on gasket tape. Should I be aiming for two rows of tape, one row above the screws, the other below the row of screws, or will one row be sufficient? I have the standard PartsExpress gasket tape...1/2" wide, IIRC. Thanks.

Now I'm considering my crossover options. Put it all on one board, or break it out into two smaller boards? I'm also mulling over placement. I'm thinking I'd like to have them mouting on the back panel. I'm assuming there's no real "better place" to mount them? OR...due to the whole "rear wave from the speaker" thing, is it best to have the back panel totally covered in damping material? I.E. don't mount the xover there?

[DJPhatman]

Use enough gasket tape to prevent any leaks. Leaks kill response. With the 1/2" wide tape, I would do 2 strips, butting up against each other, with the screws going through at the seam where the strips butt together. This will insure a good seal, and seal the screws from leaking.

Put the HP/LP filter board wherever it is convenient. Make sure you test fit with the driver installed before you commit to anything on the back cover.

[miked]

Use enough gasket tape to prevent any leaks. Leaks kill response. With the 1/2" wide tape, I would do 2 strips, butting up against each other, with the screws going through at the seam where the strips butt together. This will insure a good seal, and seal the screws from leaking.

Put the HP/LP filter board wherever it is convenient. Make sure you test fit with the driver installed before you commit to anything on the back cover.

Got it on the tape; thanks much.

I already had a test-fit in mind due to the size of the magnet on the Delta Pro drivers I'm using and my brace placement on the rear panel. Though the spacing on the braces is per the plans, I'm a little worried they might hit the magnet. I'll test tonight once I trim the horn panels and can lay the cabs flat on the face. Without the side panels on, I'll be able to get a really good look at the whole situation. Due to the size of the magnet, I may ONLY have the options of mounting the xover on the floor of the cab or side panel.

Back panel. Would be SO NICE to mount the xover dead center, b/t the braces, but it probably won't fit. It's also probably not a good idea to have the xover components only an inch away from a big old magnet.

[Bruce Weldy]

Would be SO NICE to mount the xover dead center, b/t the braces, but it probably won't fit.

You're right....it won't fit. I put mine on the side panel. If I was doing it over again, I'd glue a little 1x2" strip of ply on the side before putting on the foam to mount the xover to. Screwing into the 1/2" side doesn't leave much room for a good bite without going through.

[miked]

Thanks for that tip, Bruce. I will glue the strip(s) to the side panel before putting the foam on. Great tip. The last thing I want to do is bust through the side panel...after Duratexing. That wouldn't be good.

Bruce: BTW, how did you secure the foam behind your grills? I'm obviously not at that point yet, but trying to figure it out in advance. I'd be worried that spray glue (ala 3M 77) would leave the grill all sticky.

[Bruce Weldy]

Thanks for that tip, Bruce. I will glue the strip(s) to the side panel before putting the foam on. Great tip. The last thing I want to do is bust through the side panel...after Duratexing. That wouldn't be good.

Bruce: BTW, how did you secure the foam behind your grills? I'm obviously not at that point yet, but trying to figure it out in advance. I'd be worried that spray glue (ala 3M 77) would leave the grill all sticky.

I used one of the 3M sprays. But, you don't spray the foam - spray the grill, then pick it up and turn it over on top of the foam. Put some paper or cardboard on top of that, then more foam, grill, etc. until you have 'em all done. Then put a piece of ply with some weight on top of that until they dry.

[miked]

Spray the grill. That makes perfect sense, which I why wouldn't have thought of it. LOL! Any issues with the foam separating from the grill? With garages down here easily hitting 120F in the summer time, if they haven't separated by now, they probably never will. Thanks.

[Bruce Weldy]

Spray the grill. That makes perfect sense, which I why wouldn't have thought of it. LOL! Any issues with the foam separating from the grill? With garages down here easily hitting 120F in the summer time, if they haven't separated by now, they probably never will. Thanks.

Mine sit outside in the trailer and I haven't had one come off yet.....with makes me think I had better go check 'em before the gigs start again.

[miked]

Outside in the trailer? That would be 150F+ inside the trailer in the Jul-Sep timeframe. If they've not come off yet, they never will. I'll be going the 3M spray method then. Thanks.

I have YARDS of black grill cloth that I bought from PE probably 10 years ago...can't figure a way to make it work with a metal grill. I'm sure a few hours of tedious sewing would secure the fabric to the grill, but the sharp edge of the grill material will make short work of the cloth. Oh well.

[Bruce Weldy]

Outside in the trailer? That would be 150F+ inside the trailer in the Jul-Sep timeframe. If they've not come off yet, they never will. I'll be going the 3M spray method then. Thanks.

I have YARDS of black grill cloth that I bought from PE probably 10 years ago...can't figure a way to make it work with a metal grill. I'm sure a few hours of tedious sewing would secure the fabric to the grill, but the sharp edge of the grill material will make short work of the cloth. Oh well.

You can get the AC foam at Walmart. It's a perfect fit for the OT12s, just trim a little off. No splicing.