OmniTop 12 build

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Bill Fitzmaurice
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Re: OmniTop 12 build

#61 Post by Bill Fitzmaurice »

You may need EQ. You absolutely need a crossover. You can't send the same full range signal to the tops and subs.

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Tom Smit
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Re: OmniTop 12 build

#62 Post by Tom Smit »

Looking good so far. I have a question: is the veneer on the plywood stuck real well to the main plies?
TomS

Fastskiguy
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Re: OmniTop 12 build

#63 Post by Fastskiguy »

Tom Smit wrote: Sun Apr 30, 2023 9:51 pm Looking good so far. I have a question: is the veneer on the plywood stuck real well to the main plies?
No. Not at all. Last stuff I got was the sweet 9 ply. This was more expensive and 5 ply plus some thin ass veneer. It doesn’t hold the screws as well and has the occasional void. It isn’t warping so I’ll give it that. But I hope I can get the 9 ply for the second one.

Joe

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Re: OmniTop 12 build

#64 Post by Fastskiguy »

Bill Fitzmaurice wrote: Sun Apr 30, 2023 8:41 pm You may need EQ. You absolutely need a crossover. You can't send the same full range signal to the tops and subs.
The little 2.1 amp has a variable crossover for the sub like a lot of consumer sub amps do. Currently I’m running the tops with the full range. But is it that if I don’t have a high pass for the tops at around 100hz they’ll “fight” with the t45? I mean, it sounds decent with the sub I’m using at the moment but I do’t really know what I’m doing lol.

Joe

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Bill Fitzmaurice
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Re: OmniTop 12 build

#65 Post by Bill Fitzmaurice »

Not having a high pass on the tops amp means you're wasting amp power and driver excursion trying to reproduce sound below their pass band. That's far worse than not low passing the subs.

Fastskiguy
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Re: OmniTop 12 build

#66 Post by Fastskiguy »

Just checked the little amp to see but it looks like it's sending full range to the "tops" and variable bass to the sub. I was just hoping that it would split them up....but maybe that's a lot to ask for a $40 amp. It'll low pass the subs though....so maybe that's something (but probably not much!)

So does everybody have this problem or am I just inadvertently going about the the hardest possible way? Should I be looking at an inexpensive X.1 receiver and then running bluetooth adapter->some kind of equalizer->2.1 receiver?

Joe

Bruce Weldy
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Re: OmniTop 12 build

#67 Post by Bruce Weldy »

Fastskiguy wrote: Mon May 01, 2023 4:30 pm Just checked the little amp to see but it looks like it's sending full range to the "tops" and variable bass to the sub. I was just hoping that it would split them up....but maybe that's a lot to ask for a $40 amp. It'll low pass the subs though....so maybe that's something (but probably not much!)
So, is this the little Lepai amp you referenced a few pages back? If so, the manual is pretty worthless, but it does say that it crosses over the sub. The way it said it is less than definitive.

Here's what you do. Unhook the subs from the amp. Run a 100 hz signal (or even some music) through it. As you listen, turn the crosoover frequency higher - as you do, you should hear the bottom end disappear. If it doesn, then the amp is highpassing bases on the crossover point. Do the same thing in reverse - unplug the tops and run just the subs. You should here higher frequencies as you increase the crossover point. If so, then it's lowpassing too.

If it doesn't high pass the tops (and it may not), then you'll want to get something a little more sophisticated.....OR.....if you are happy the way it sounds, then crank it up, enjoy it, and don't fret with it anymore.....ultimately, that's all that matters.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Fastskiguy
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Re: OmniTop 12 build

#68 Post by Fastskiguy »

Bruce Weldy wrote: Mon May 01, 2023 4:47 pm So, is this the little Lepai amp you referenced a few pages back? If so, the manual is pretty worthless, but it does say that it crosses over the sub. The way it said it is less than definitive.

Here's what you do. Unhook the subs from the amp. Run a 100 hz signal (or even some music) through it. As you listen, turn the crosoover frequency higher - as you do, you should hear the bottom end disappear. If it doesn, then the amp is highpassing bases on the crossover point. Do the same thing in reverse - unplug the tops and run just the subs. You should here higher frequencies as you increase the crossover point. If so, then it's lowpassing too.

If it doesn't high pass the tops (and it may not), then you'll want to get something a little more sophisticated.....OR.....if you are happy the way it sounds, then crank it up, enjoy it, and don't fret with it anymore.....ultimately, that's all that matters.
That makes perfect sense....with no sub hooked up I adjusted the crossover frequency....no change. With just the sub hooked up it did change. So I'm pretty sure there is no high pass to the tops but there is a variable low pass to the sub.

But I like your idea of "just try it out and see". I mean....the T45 isn't even up and running yet so maybe it'll sound good enough. Heck, it sounds good enough now, just need a little more low end. I'll give it a shot :)

Joe

Fastskiguy
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Re: OmniTop 12 build

#69 Post by Fastskiguy »

On a completely different topic....I'd like to put some kind of fabric grill over the speakers and sub, just to keep bugs and some of the dust out of them. The edge is 1/2" wide...is there an easy way to do it? And am I looking for anything special as far as fabric? Thanks :)
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Grant Bunter
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Re: OmniTop 12 build

#70 Post by Grant Bunter »

Fastskiguy wrote: Mon May 01, 2023 7:02 pm On a completely different topic....I'd like to put some kind of fabric grill over the speakers and sub, just to keep bugs and some of the dust out of them. The edge is 1/2" wide...is there an easy way to do it? And am I looking for anything special as far as fabric? Thanks :)
Sure.
Make a frame that fits just inside the cab edges with a gap big enough for the cloth, cover that with "speaker grille cloth" (fold over the back of the frame and staple on to secure).

To attach, add some small blocks to the inner side of the cab (enough so the grille won't flex) that determines depth of the grille.
Add some magnets to the blocks and the grill and it should snap in place. Or same thing with fancy do dad speaker grille mounting parts (one half will be male, the other female).

Or go nuts; check out my DR250 build thread on page 2.
About 3/4 of the way through that, you'll see what I did for grille, which now has 1/4" speaker grille foam behind it...
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...

Bruce Weldy
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Re: OmniTop 12 build

#71 Post by Bruce Weldy »

Fastskiguy wrote: Mon May 01, 2023 7:02 pm On a completely different topic....I'd like to put some kind of fabric grill over the speakers and sub, just to keep bugs and some of the dust out of them.
Grills - yes....fabric- no. If they are going to be outside, it's easier to wipe down the inside than to try and get the dust off of fabric. My T24 has been sitting in my garage since I built it. I just hit it with the air hose every now and then. And the SLA has a grill with foam behind it....with all the sawdust I create in there - it just doesn't hold any dust.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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Bill Fitzmaurice
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Re: OmniTop 12 build

#72 Post by Bill Fitzmaurice »

Grille options are shown in the plans and the sketchup model.

Fastskiguy
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Re: OmniTop 12 build

#73 Post by Fastskiguy »

Oh awesome, thanks guys for the grill ideas :)

Today was a big day for the T45....say it with me...."Generous Bead"!!!

She's all sealed up, never to be opened again. Historic!

Ok, who among us write fun little thoughts inside just before closure? I know I always do!
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howiez
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Re: OmniTop 12 build

#74 Post by howiez »

Looking great!

Fastskiguy
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Re: OmniTop 12 build

#75 Post by Fastskiguy »

I came up a bit short on the bottom edge and glued on a thin strip of plywood. Hit it with the router and Duratex and it turned out ok. Just wanted to throw in a little something….it is a build thread after all.

Joe
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