Weatherproof Otop 15 Build . . . finally

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Hackomatic
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Weatherproof Otop 15 Build . . . finally

#1 Post by Hackomatic »

Not sure if this is an historic occasion or not, but at least as far back as I could dig, I found no other Otop 15 build thread . . so here goes! As a number of you know I've been kicking this one around for awhile. Lots of good ideas and options, but eventually, after sifting through it all, I had to make a decision and pull the trigger.
Sanity check in order . . .
I've decided to give sheet PVC a try . . Gray, type 1, 1/2" thick, AND INCREDIBLY HEAVY! I knew that when I ordered it, but realizing this will be a permanent install without repeated schlepping, I ignored the back breaking properties. 8- 2 X 2 sheets, 120 lbs. :shock:
PVC sheet.jpg
The re-coned Delta Pro 15 needing its tinsels trimmed and a coat of Wet Look sealant on the paper, begging for a place to land . . .
Delta Pro recone.jpg
. . AND the high frequency section with the LP/ HP filter components. Again, preferred CD drivers, so got 4 JBL/ Selenium D202Ti drivers with HM 17-25 lenses. The 202s use the identical diaphragm as the 220s but with a smaller magnet and therefore smaller diameter, they will nestle nicely into the mouth. The four lenses stacked will fit PERFECTLY into the opening of the Otop 15. Jantzen 15 gauge .6mH choke and a 15uF Audyn cap for the woofer, and 10uF Audyn blockers for the 4 CDs.
Horn Array.jpg
Not real sure when I'll start paring plastic, but I have the beginnings of a good prototype in front of me. Figure when I get done slicing and dicing, these things are likely to come in in the 80 to 90 pound range. I guess we'll find out . . :lol:
Ice storm going on right now so I may end up in the dark, but I'm gonna start assembling the filters and get them out of the way.

Stay tuned! :fingers:
Dave H

jimbo7
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Re: Weatherproof Otop 15 Build . . . finally

#2 Post by jimbo7 »

1/2" solid plastic seems like overkill. I don't think any of the plastic cabs come that thick. Would 1/4" or 3/8" worked too? I know modifiying plans for material thickness is a PITA but jesus!

Waiting for updates
BFM builds:
XF212
T24 BP102 24"
2x SLA's 6-5" mids, 9- gt-302's
2x AT 14" MCM 55-2421
TrT 5" MCM 55-2421
AT 18" JBL GTO804
2x OT12 flat array
2x SLA Pro 2-Alpha 6's 2-Goldwoods
2x T39 24" 3012lf
Simplex 10 BP102

miked
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Re: Weatherproof Otop 15 Build . . . finally

#3 Post by miked »

Hey, no kill like overkill, right? I am assuming you will use some PVC cement to assemble the cab? Not sure if PL will stick to plastic. I would also run beads of silicone on all seams to ensure air tightness, as well as to ensure no water seeps in.

On a weird, related note; I have always thought that those 1" thick PVC partitions you see in restrooms would make for some solid subwoofer boxes. :loler:

Been looking forward to this build!

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#4 Post by Hackomatic »

miked wrote:Hey, no kill like overkill, right? I am assuming you will use some PVC cement to assemble the cab? Not sure if PL will stick to plastic. I would also run beads of silicone on all seams to ensure air tightness, as well as to ensure no water seeps in.

On a weird, related note; I have always thought that those 1" thick PVC partitions you see in restrooms would make for some solid subwoofer boxes. :loler:

Been looking forward to this build!
I like the way you think! Yes . . The thick, gray PVC cement that, of all things, is designed to fill the gaps. :lol: And again, yes . . beads of silicone on all the seams. I'm even considering doing that around the back cover . . could always be removed with a utility knife if access was necessary. In addition to the NL4MPR on the bottom, I'll be cutting the ports down there as well and mesh them to keep trespassing pests at bay.

Oh . . and these will be bi-amped. QSC GX5 and GX3
Dave H

miked
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Re: Weatherproof Otop 15 Build . . . finally

#5 Post by miked »

I'm scratching my head a little bit...I'm assuming a 15" OTop is built the same way as a 12" OTop? I.E. the cab looks exactly the same, just larger.

Per the plans, the ports/handles are supposed to go on the sides. Many have wanted to put them on the back panel or the horn panels (of all places) but I've never heard of anyone putting them on the bottom. I know (very) little bit about ported cab design, but I know you don't want to put a port where it would be in a "direct reflection line" (that's a highly-technical term I just invented) with the rear of the cone. I.E. the back panel or the horn panels would be a very bad idea. Frankly, I don't see a diff b/t putting the ports on the side or the bottom panels, so hey, thumbs up, buddy. Of course I will defer to Master Yoda on that.

Being that you will be bi-amping, you won't have passive crossovers taking up space inside the cab, so making adequate room for the ports shouldn't be a problem. Just be sure that you allow enough "breathing room" around the ports with the mattress topper or whatever absorbent material you use.

I noticed you specified two amps for biamping....I'm assuming you're building a pair? The GX series aren't bridgeable, so you must be building a pair. The GX series punch above their weight; a pair of 15" OTops with the CDs you're using with those two amps will cover a football field nicely. Albiet a highly directional coverage, but darn if it won't be LOUD AND CLEAR.

Please post lots of pics. AFAIK, you're actually "making a first" here by building OTops out of PVC. So cool. 8)

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#6 Post by Hackomatic »

miked wrote:I'm scratching my head a little bit...I'm assuming a 15" OTop is built the same way as a 12" OTop? I.E. the cab looks exactly the same, just larger.

Per the plans, the ports/handles are supposed to go on the sides. Many have wanted to put them on the back panel or the horn panels (of all places) but I've never heard of anyone putting them on the bottom. I know (very) little bit about ported cab design, but I know you don't want to put a port where it would be in a "direct reflection line" (that's a highly-technical term I just invented) with the rear of the cone. I.E. the back panel or the horn panels would be a very bad idea. Frankly, I don't see a diff b/t putting the ports on the side or the bottom panels, so hey, thumbs up, buddy. Of course I will defer to Master Yoda on that.

Being that you will be bi-amping, you won't have passive crossovers taking up space inside the cab, so making adequate room for the ports shouldn't be a problem. Just be sure that you allow enough "breathing room" around the ports with the mattress topper or whatever absorbent material you use.

I noticed you specified two amps for biamping....I'm assuming you're building a pair? The GX series aren't bridgeable, so you must be building a pair. The GX series punch above their weight; a pair of 15" OTops with the CDs you're using with those two amps will cover a football field nicely. Albiet a highly directional coverage, but darn if it won't be LOUD AND CLEAR.

Please post lots of pics. AFAIK, you're actually "making a first" here by building OTops out of PVC. So cool. 8)
From the Master himself . .second post down . . .
http://billfitzmaurice.info/forum/viewt ... =3&t=20634

Actually, the plan is to build four of these things . . ultimately! 8) . . .The system was originally built and wired for discreet Left/ Right audio. It sounded pretty cool when the recorded material had been mixed with hard left to right pans . .sound effects as well, left to right . .especially the "Wildcat" roar when the home team made a first down!

And that is where I'm going to seek out the collective's insight on placement based on what I have to work with. Pictures of that arrangement will be forthcoming . . .
Dave H

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#7 Post by Hackomatic »

Got the panels all drawn up y-day. Fiddled with the filters today. Mounted the components on some salvaged polycarb.Crimped and soldered ring connectors on everything, a dab of silicone sealant/ adhesive on the bottom of the caps and coil, and of course, the obligatory cable ties to secure the coil and keep it there.
Voila!
Filters.jpg
Dave H

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#8 Post by Hackomatic »

Just so I don't run out of things to think about, make some plans on the "complete" project, and enlist the opinions, knowledge and experience of the group, here is what I'm facing . . .
stadium config.jpg
The pic is from 2005, before the four 20 foot towers and (what are now former) speakers were in place, hence the crude graphics. The system was (is) set up as a tri-amped arrangement. Each tower having a bi-amped 2-way on top and a separate amped sub on the bottom . .8 cabs total. The Press box had (has) two additional 18" sub boxes PLUS another pair of horns on top of those. Despite all the combing and nulls, if you sat in one spot it sounded pretty darn good, walk down the track perpendicular, however, and YIKES! :lol: Everything was reflex direct radiator. The two little cones showing at the top of the outside towers are Atlas Sound CobraFlex horns driven by the aux 1 send buss on the Yamaha console. The one on the right faces the parking lot, the one on the left, the concession stand. Their purpose is simply to carry the PA announcers voice to the far reaches of the site not covered by the other speakers. Nothing but voice goes through them. The big round horns on the big tower behind the press box do nothing except provide a place for wasps to build their nests.

So . . gimme some thoughts on how to arrange the 4- Otop 15s on the towers, any additional subs, and also think along the lines that I may eventually V plate a pair of T48s on the press box roof.
:feedback:
Dave H

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DJPhatman
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Re: Weatherproof Otop 15 Build . . . finally

#9 Post by DJPhatman »

They have to go as in the picture?
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#10 Post by Hackomatic »

DJPhatman wrote:They have to go as in the picture?
Not necessarily. . The four towers are permanent fixtures, and I'm pretty sure they school is not gonna want to move them. BUT. . what if the cabinet configuration was shuffled? As in, splayed Otops on the inner towers with subs on the outer towers? or vice versa . . . And the press box roof can become whatever is necessary. I'll entertain all ideas . .short of relocating the four towers. :?
Dave H

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Re: Weatherproof Otop 15 Build . . . finally

#11 Post by Grant Bunter »

Subs work best on the ground.
If you stick them up on the poles, you'll simply need more...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Re: Weatherproof Otop 15 Build . . . finally

#12 Post by DJPhatman »

Grant Bunter wrote:Subs work best on the ground.
If you stick them up on the poles, you'll simply need more...
+100. Having the subs off the ground puts them in free space, or -6dB, IIRC. I know for sure it is NFG. As far as tops placement is concerned, I would want to be able to place them near each goal line, turned in toward the center of the field, for the most coverage. Put the subs on the ground, under the bleachers if possible.

You could also place all 4 OTops on top of the press box, 2 on each side, cross-fired for maximum coverage, and tilted probably 15-30 degrees down.
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#13 Post by Hackomatic »

Yeah, I'm painfully aware that subs work better at ground level. Unfortunately, the chances are pretty much zilch on being able to do that. As you will notice in the pic, the bleachers are in the side of a hill . . nothing but solid concrete where the seats are set. I fear sub placement will end up being a series of compromises, or as Grant points out just keep building and adding!
Dave H

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Re: Weatherproof Otop 15 Build . . . finally

#14 Post by Grant Bunter »

Hackomatic wrote:Yeah, I'm painfully aware that subs work better at ground level. Unfortunately, the chances are pretty much zilch on being able to do that. As you will notice in the pic, the bleachers are in the side of a hill . . nothing but solid concrete where the seats are set. I fear sub placement will end up being a series of compromises, or as Grant points out just keep building and adding!
Yep.
I'm pretty sure DJP's assessment of -6db sounds right by putting them up in the air.
That means you will need to double cab count to bring you back to equivalent of ground placed subs.
But if you throw in a V plate on a pair, that normally ups output by 3dB, but will not be that figure when not at ground level. Maybe half ie 1.5dB.
So if you built 4 cabs, put them up on the booth and V plated both pair you might be, at best, a bit above a pair V plated on the ground...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Hackomatic
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Re: Weatherproof Otop 15 Build . . . finally

#15 Post by Hackomatic »

Sounds like I'm gonna need to do a structural analysis of the roof! And speaking of the roof . . is there any thing to be gained by its boundary?
Dave H

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