OTop8 dispersion angle and Bi-amping

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Keryn O'Shea
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Location: Brisbane, Australia

Re: OTop8 dispersion angle and Bi-amping

#61 Post by Keryn O'Shea »

Thanks for the kind words Lads!
Seth wrote: Wed May 21, 2025 9:58 am Which amp/s did you run it all on?
20250520_192536.jpg
A CVR2004 for subs & mids, and a 2x800w amp l built with Wondom modules & a 60v DC power source for HF.
https://store.sure-electronics.com/product/638
Further feedback from neighbours two properties up, felt Astrix through their concrete floor, and others 1/8 mile away (the system was facing them) couldn't hear their TV inside the house :D
Is there any sense in spiralling the array for the nutters who want the be right up close to the stage, this for example, would be the LH side
20250519_104927.jpg
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FA, J12 FA, OT8 CD, OT12 FA, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 MA, XF210. Next J10L

Keryn O'Shea
Posts: 559
Joined: Sat Jan 26, 2013 5:50 pm
Location: Brisbane, Australia

Re: OTop8 dispersion angle and Bi-amping

#62 Post by Keryn O'Shea »

And Seth,
This one is following your lead...
20221113_160504.jpg
This is how l feel when thinking about, working on, looking at or listening to Bf cabs.
And also when cruising the forum seeing what you guys are up to :D
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FA, J12 FA, OT8 CD, OT12 FA, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 MA, XF210. Next J10L

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Bill Fitzmaurice
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Re: OTop8 dispersion angle and Bi-amping

#63 Post by Bill Fitzmaurice »

Yes, you can spiral the array. For the best result the mouths of the HF horns should be in a vertical line. That will minimize any comb filtering of the highs. The mouths of the low frequency sections need not be on a vertical line as the wavelengths they pass are too long to require it.

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Seth
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Re: OTop8 dispersion angle and Bi-amping

#64 Post by Seth »

Keryn O'Shea wrote: Thu May 22, 2025 4:25 am And Seth,
This one is following your lead...
It's darn near like meeting you in person, putting a face to the name.

Thanks for that, Keryn.

As far as the subs go, it won't really matter where they're aimed. The dispersion angle/pattern of those frequencies are 360º for a stack that size. You could aim them at the sky, at the ground, toward the audience, away from the audience... won't matter much at all outdoors. Indoor placement though, that's where placement and orientation can make a huge difference.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Keryn O'Shea
Posts: 559
Joined: Sat Jan 26, 2013 5:50 pm
Location: Brisbane, Australia

Re: OTop8 dispersion angle and Bi-amping

#65 Post by Keryn O'Shea »

Bill Fitzmaurice wrote: Thu May 22, 2025 6:49 am Yes, you can spiral the array. For the best result the mouths of the HF horns should be in a vertical line. That will minimize any comb filtering of the highs. The mouths of the low frequency sections need not be on a vertical line as the wavelengths they pass are too long to require it.
Understood 👍
Seth wrote: Wed May 28, 2025 1:10 am You could aim them at the sky, at the ground, toward the audience, away from the audience... won't matter much at all outdoors.
If the T48s were to be setup outdoors in a line with the horn mouths towards the top..
20250507_073657.jpg
There'd be no noticeable difference? This wouldn't look as appealing, but is easier setup as they'll be trucked out of the trailer upside down
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FA, J12 FA, OT8 CD, OT12 FA, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 MA, XF210. Next J10L

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Bill Fitzmaurice
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Re: OTop8 dispersion angle and Bi-amping

#66 Post by Bill Fitzmaurice »

No measurable difference either, so long as the bottom of the cab is less than 1/4 wavelength from the ground. At 100Hz that's 85 Cm.

Keryn O'Shea
Posts: 559
Joined: Sat Jan 26, 2013 5:50 pm
Location: Brisbane, Australia

Re: OTop8 dispersion angle and Bi-amping

#67 Post by Keryn O'Shea »

More great news, thanks mate :)
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FA, J12 FA, OT8 CD, OT12 FA, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 MA, XF210. Next J10L

Bruce Weldy
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Re: OTop8 dispersion angle and Bi-amping

#68 Post by Bruce Weldy »

Bill Fitzmaurice wrote: Sat Jun 07, 2025 4:01 pm No measurable difference either, so long as the bottom of the cab is less than 1/4 wavelength from the ground. At 100Hz that's 85 Cm.
But, won't gravity make all the sound fall to the bottom of the cab?

:mrgreen:

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: OTop8 dispersion angle and Bi-amping

#69 Post by Bill Fitzmaurice »

An audiophool would say so. :roll:

Keryn O'Shea
Posts: 559
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Re: OTop8 dispersion angle and Bi-amping

#70 Post by Keryn O'Shea »

Bill Fitzmaurice wrote: Thu Jan 23, 2025 4:22 pm Black hot melt glue.
I finally got around to doing this, and it turned out much better than l thought! Great tip there, cheers Bill :)
20250614_155858.jpg
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FA, J12 FA, OT8 CD, OT12 FA, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 MA, XF210. Next J10L

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