First Build: Omni Top 112s

[Tom Smit]

Which reminds me, what is rigid foam? insulation?

Yes

[ripNdeb]

ttt with plug extensions question:
three or four?
Plans text says three; pictures and Sketchup show four (from the baffle).
I'm going to use Kappalite 3012HOs, 5" plug and extensions, no slots in the baffle.
Thanks in advance,
Dana

[ripNdeb]

Well, since no one was answering my question, I had enough time to actually come up with my own phase plug extension design. I figured the answer was probably three extensions, like the plans text says. But, what if it was indeed four like the plans pictures and Sketchup says; wouldn't that be better? Then I started thinking, "What if I just used all six that I had cut out so far?" Surely that would be better still:


Then I thought, "Why stop there?". I could use this old coffee cup and have the best extension ever!!!

[Bill Fitzmaurice]

Well, since no one was answering my question, I had enough time to actually come up with my own phase plug extension design. I figured the answer was probably three extensions, like the plans text says.

Read them again, there is a procedure for determining the extension depth.

[ripNdeb]

Read them again, there is a procedure for determining the extension depth.

Touche'; but I don't have the drivers yet
And, I did see that section. And, I have read the plans; a lot.
Now, with two 'read the plans' responses in one thread, I will shut up and just do the best I can.

[ewetho]

Relax and keep asking. We all stumble on to stuff that we miss or just does not make much sense because we come from different point of views. But if it is in the plans we will be glad to point you back to the source. At least generally you know that it will in fact be there and you just missed it. Better than pulling your hair out thinking it is not there.

Keep plucking away and don't be afraid of asking. You just may need to find a certain piece of info on Pg 14 while on 4 or something.


Those cabs sound real nice. You will love them.

[Tom Smit]

Well, since no one was answering my question, I had enough time to actually come up with my own phase plug extension design. I figured the answer was probably three extensions, like the plans text says. But, what if it was indeed four like the plans pictures and Sketchup says; wouldn't that be better? Then I started thinking, "What if I just used all six that I had cut out so far?" Surely that would be better still:
[img]/images/OTop9.jpg[/img]

Then I thought, "Why stop there?". I could use this old coffee cup and have the best extension ever!!!
[img]/images/OTop8.jpg[/img]

ROTFL!

[ewetho]

He should see the bronze propeller nuts we used in the navy that would give that smooth transition to a fine point. Or the lightweight aluminum ones for small or model aircraft.

Think Bill mentioned before not much advantage or worse. On the driver side beforelong you'llhit the driver so that won't work either.

[ewetho]

Hey I know I am bogarting the thread a bit but for those who have built both especially those who have both the last design with the slot and the new phase plug designed OTops (12 or 15)...

How do you compare the 2 designs?

[doncolga]

After about one month or so of making NO saw dust, here is the current state of my OT12's.

http://www.flickr.com/photos/monoheadph ... otostream/

http://www.flickr.com/photos/monoheadph ... otostream/

Right out of the gate I discovered a problem. One of the panels had separated a little from the top...I believe some wax paper may have gotten stuck into the joint and the PL didn't set good. I clean it up re-PL"ed and screwed this time. I didn't have the screws before, so I'm comfortable that it's stuck and sealed. Man, do I ever work slow....

[loudsubz]

I just started building 4 of them with a buddy yesterday. Just need phase plugs, mounting ring, and back and box is done. Melded array is another issue

[doncolga]

CRAP!!!! One of my boxes is turning up a bit off square...guess I'll see the best way to fix it...trying to find the best place to minimize this. I wouldn't say these have been hard, but the Tubas seemed alot easier to me.

[ripNdeb]

First major blunder:
I used a random orbital sander to take down a high edge on one of the back corners. Happily sanding away, trying to match the lower edge, I was wondering why when I was pulling the sander toward me it felt like it was working so much better. The red flag was thrown but I chose to ignore it.
This is the lovely result:



I didn't even notice it until after I had corner rounded the back edges, including this one, and stood it up on it's side to admire my work.
Do you think this a job for bondo or should I try to fashion a little shim type of piece to repair it? It is about an eighth inch lower now.

[LelandCrooks]

bondo

[ripNdeb]

Does the space above and below the melded array on the OT112 make a difference? Does the reflector use that space to, well, to reflect?
The reason I ask is I made this great tweeter jig, slightly (1/8") oversized so when finished the array will be 3/4" taller. The extra leaves enough for a near perfect mounting hole between each element ( I realize I don't need these extra holes but it could come out looking similar to the DR250 on the home page) AND leaves a ridge intact for extra strength.



Hopefully my 45 degree angle jig will work this nicely. Looks like I could possible glue a couple together and cut two at once when I make the 45s?

Edit: in the pic, they are just sitting there on the counter, not glued yet