Best Ending to a Long Weekend - OT12s

[kkip]

A coat of Durtex of course!

[kkip]

My second pair of OT12s. This pair will be loaded with Deltalite 2512s and Selenium D220Ti compression drivers. Started them just over two weeks ago. Definitely my fastest build ever. But I already had the diffusion horns and crossovers built before starting the cabinets. They are made mostly out of AraucoPly. However, I did buy baffles and spacers from Leland to save a little time. So those parts and the compression horns are made with Baltic Birch.

Now I just need to complete another pair of T-39s by mid June! Here are a few more build photos.

[commander_dan]

Looking good! Can't wait to build my first pair of Otops!

[kkip]

Another busy week, unfortunately not a lot of time to finish up the build. I did manage to get the cabinets covered with two coats of Duratex, mounted the diffusion horns, installed the damping material and installed the connector plates.

Also, I've included a picture of one of the 2KHz compression driver crossovers that I built earlier. If anyone is interested, I was able to re-purpose a 2-way crossover bare circuit board from Parts Express (Part #260-116) to build the crossover. Note that I followed the circuit from the OT12 plans, not the schematic or placement diagram that came with the circuit board.

[kkip]

I finally finish up the OT12s. I am delighted with the way they came out. Also, they sound great. In fact, they sound so good that I was concerned that there might be something wrong with my older pair. It may be that I simply prefer the tone of the compression driver over the melded piezo array. But there is a noticeable dip in the older cabinets at the crossover point and they sound a little honky. But I tore one apart and tried reversing the connection to the melded array, but that didn't help. I also checked the array wiring and the crossover, but everything was correct.

Here are a couple pictures of the new build after final assembly.

[J_Dunavin]

Looks great! Where did you get your grill material from?

[Tom Smit]

Very good!

[doncolga]

Those look awesome. I really should put a grill and new coat of Duratex on mine.

[kkip]

I had the grills made by eBay seller spkrparts!-2007. He sells several standard sizes, but will make other sizes if you ask for a custom quote. I ordered these 20" x 14" x 1/2". Then I cut 1/2" strips of 1/2" plywood to make a frame for each. I painted them black and screwed them on from the front. I've seen some other members use a slick side-screw mounting technique. But I am fine with the screws in the front.

Here is a link to one of the standard size grills.
http://www.ebay.com/itm/Pair-15-x-22-x- ... 415a5423c5
I know that there are several other members who have used these grills. They are similar to the grills made by Reliable Hardware, but are generally less expensive. Also he can make them pretty quick. Mine were shipped within a couple of days of ordering.

[commander_dan]

Thanks for the grill link! I'll be squirreling that one away for when I get my otops underway

[kkip]

I did some outdoor RTA testing and ran a DEQ auto-EQ on these Omnitops. I found that although I am pleased with the way that they sound, they are a little hot in the 2K-8K region. Not horrible, but they did take a bit of EQ cutting in that region to make them flat.

After doing the tests, I went back and looked at the spec sheet for the Selenium TI220 compression driver that I used vs. the recommended Eminence ADS drive. Sure enough the TI220 is 4-5db more sensitive. In hindsight, I think the 16 ohm version of the TI220 (and 16 ohm crossover) would have been a better match. I guess I could go back and retrofit with the 16 ohm diaphragm and update the crossover. It might be worthwhile to flatten then a bit.


I have a question for those who have used the DL 2512. Given the tight spacing behind the motor assembly, I did cut out an area in the dampening material. But when peaking in through the handle hole, it looks like barely enough. Does this look like enough in the attached photo? Has anyone had heat problems with these 2512s? I haven't run these hard yet, but will this weekend.

[Bill Fitzmaurice]

I have a question for those who have used the DL 2512. Given the tight spacing behind the motor assembly, I did cut out an area in the dampening material. But when peaking in through the handle hole, it looks like barely enough. Does this look like enough in the attached photo?

Even 1/8 inch will allow sufficient air flow.

[kkip]

]Even 1/8 inch will allow sufficient air flow.

Great, glad to not have to crack them open!

[Bill Fitzmaurice]

Great, glad to not have to crack them open!

Do so anyway after using them a couple of times to re-torque the screws, as the gasket will probably compress a bit.