OTop12 and T45

[Chips and Palsa]

Hello Wonderful forum members! After much reading and second guessing of SPL charts vs pack space vs intended use, I HAVE DECIDED! For house parties and backyard barbecue all around fun (with the ability to scale in the future), I will be building one 2512 loaded melded array OTop12 and one LAB12 loaded 18" Wide T45 (I like a lot of bass-heavy electronic music)

Using a great online panel cut optimizer, I found that I can get this whole build to fit on 3 sheets of BB after I downsized the T45 to 18" wide. Which brings up a question. According to Bill's plans, panels up to 17" in width require only 1 set of braces. I have heard that panel flex robs performance from Subwoofers so being on the outer limits of a single brace cab, would I be gaining anything from adding an additional set of braces (even if its just to the mouth of the cab) or is the single set plenty for an 18" outside width T45?

Back to the build:



Very happy to have access to a HAAS CNC. It made cutting the OT Baffle a breeze!





Can't Wait to make progress on this big guy!



More updates in the near future. Thanks for looking everyone!

[Grant Bunter]

Looking good!

Braces:
If your panels are 17" wide for 18" wide cabs, then 1 brace is fine, as per the plans.
If you panels are 18" wide, go with 2 braces.
If your panels are 17" wide and your concerned, it's DIY, put in 2 braces...

[Tom Smit]

A single brace between each panel of your build is plenty. I think that Bill errs on the side of safety by keeping it down to 8" rather than using a larger distance.

[Chris_Allen]

A single brace between each panel of your build is plenty. I think that Bill errs on the side of safety by keeping it down to 8" rather than using a larger distance.

With birch yes, but with softwood ply, there is far more flex.

[Chips and Palsa]

With birch yes, but with softwood ply, there is far more flex.

Good to know. I was astounded at how much more solid the OT12 Baffle felt than the pieces of Arauco I used on the AutoTuba.

I should have the corners, casters, and top hat coming in the mail today. Now I've gotta see if I can sneak a Deltalite or a LAB12 onto the birthday list

School and work is keeping me super busy during the week so this may have gotten pushed to weekend build status But thanks to the helpful Eminence Spec Page, I'll try to get the driver spacers cut ASAP with no shortage of help from the machine shop!

Now, off to SolidWorks to come up with a cool single brace setup...

[escapemcp]

Don't forget to include the braces in your sheet layout, especially if doubling up on them.

[Chips and Palsa]

Don't forget to include the braces in your sheet layout, especially if doubling up on them.

Definitely going to need to grab some more wood for this! Really diggin' the Cerwin Vega style bracing. Would like to use 3/8" if I go this route, or more Arauco. Now I just need to figure out how to brace the rest of the inside without adding a bunch of weight.

[Chris_Allen]

That does look nice, especially the grey finish.

[MissileCrisis]

Don't forget to include the braces in your sheet layout, especially if doubling up on them.

Definitely going to need to grab some more wood for this! Really diggin' the Cerwin Vega style bracing. Would like to use 3/8" if I go this route, or more Arauco. Now I just need to figure out how to brace the rest of the inside without adding a bunch of weight.

Window all your braces to save weight. Meaning cut out the centers. Typically it isn't done on the small braces because it only saves like 3 pounds total. But hey if that's worth it go for it.

[DJPhatman]

Definitely going to need to grab some more wood for this! Really diggin' the Cerwin Vega style bracing. Would like to use 3/8" if I go this route, or more Arauco. Now I just need to figure out how to brace the rest of the inside without adding a bunch of weight.

Use 1/4" Baltic birch and 1/16" to 1/8" deep dados for the braces. Saves half the weight over 1/2" Baltic birch, but is still very strong and stable.

[Chips and Palsa]

Those are all good points for the bracing. I may need to source another approved grade of ply though... Not sure if the old Chevy is up for another 2 hour trip for some BB!

Super Excited for the speakers to arrive tomorrow!! Can't wait to see that hefty beauty known as the LAB12

Also rather astonished at how big the 15uF Cap and the 15AWG low-pass inductor is! Speaker building is really making my electrical engineering concepts class much more interesting. (Coming from a Mechanical who formerly accepted electricity as magic)

Some good times in the OTop camp this weekend too!





I busted out the cast iron Craftsman table saw for the throat panels and now I'm sincerely depressed that it only has a 2 ft wide table IT MAKES LIFE SO EASY! Looking forward to making a jig for cutting 45s on the tweeters.

...Which brings me to my next question...

While at work one day I used the Bridgeport mill to trim tweeter frames down. I had started by band sawing off the majority and milling the rest down to the molding rib thats located halfway down the mounting hole.




Some quick math shows that with top and bottom tweeters containing only one trimmed side and all of the in-betweens at 2.15", the full array would still come in at 13.4" total height. In favor of more material to bond while gluing, is there any reason I cannot leave these tweeters at 2.15" outside height?

Thanks for replies!

[escapemcp]

I ended up cutting mine too much, and had to use 14 (7x2) tweeters in my melded array, rather than the usual 12. Has caused no issues at all The only worry about going the other way would be if the centre to centre spacing on the tweets becomes too much - can someone (with more knowledge than me) chip in to confirm/deny if this would be a problem?

You might want to make them a touch smaller than 2.15" if you are 'allowed' to do it, as you probably don't want them touching at the top/bottom. I've never liked the gaps at the top & bottom of the array... and I think the Wedgehorn's setup of 4 tweets on a pair of sticks is just plain ugly (sorry Bill!), but I guess that's what foam backed grilles are for. Bet those WHs still sound good tho

[ripNdeb]

"In favor of more material to bond while gluing"
I asked this very same question and the answer was they are cut that way to keep them as close together as possible for HF coupling/HF integration/or, something like that. Stick to the plans. I thought 'WOW' perfect jig!!!. I had to shim it up a little on the first cut to get the desired result from the plans. Worked out well.

[Chips and Palsa]

GRRR I MADE A BIG MISTAKE (Kind of)

Whilst attaching the top panel I had noticed that the horn panels were going to have an uneven amount of overlap so I loosened the attaching screws and gave it a shimmy, not realizing this would be the trickle down effect:



DARNIT! My OCD already brought up the fact that a perfectly square cab is only $26 and a truck ride back to the lumberyard...

We shall see how the DuraTex hides this goof up. After all, the warp could be emphasizing it since with a little manipulation:



(Its much less out of wack than the pictures suggest) I should only have to deal with 1/16" trimming after I attach them tomorrow)



(A little End mill cleanup after hole sawing)

Meanwhile, I've constructed this guy for assistance



And the tweeters came out (to the correct 2" height) wonderfully!



(test setup, not gluing)

I've also have big plans for finishing up my AutoTuba nicely with Duratex and even a Speakon on the access panel for use with the OTop until the T45 is ready to roar.

Officially fallen in love with this thing


I had been set on a Pioneer DDJ-SR until I found this Vestax VCI-380 for less money with more awesome features! Gonna be a little while before that comes around though...

hoping to get some music playing through the OTop sometime in the next week or 2!! Thanks for staying tuned guys!

[sine143]

keep your eyes peeled for used vestax controllers. DJtechtools forum has a pretty active buy/sell forum. Its likely you could snag the 380 for around $200 in very good condition.