OT15 - XO to sub and nominal gain?

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burnsze15
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OT15 - XO to sub and nominal gain?

#1 Post by burnsze15 » Mon Jan 18, 2021 11:49 am

Two seperate questions:

1. I have folded horns curently with a top response of 120hz. For the OT 15, would a 100-110 hz XO seem pretty smooth? Building with the 3015. It seems it comes into its wheel house around 120 or so. The -3db point would be just about 120hz as I see it. Where are you guys crossing your OT12 and 15s to the subs?

2. Looking to confirm Im calculating the nominal spec gain from the KL3015 to the cabinet design gain to be about 5-6db across the 150-1000hz spectrum (average)?

I ask because I may try and use these for mids in a MTM or MMT large format modular horn project (XO to a mid/high coaxial around 500-700hz). I inagine there would be no detriment to having the comp driver disconnected in the path of the midbass/midrange propogation pattern (vs removing the CD assembly)

Thanks for the help.

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Bill Fitzmaurice
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Re: OT15 - XO to sub and nominal gain?

#2 Post by Bill Fitzmaurice » Mon Jan 18, 2021 11:58 am

There is no advantage to an MTM, and quite a few disadvantages, compared to the coincident stock HF horn of the OT12 and OT15.
I'll leave the crossover frequency question to users.

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Seth
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Re: OT15 - XO to sub and nominal gain?

#3 Post by Seth » Mon Jan 18, 2021 1:08 pm

burnsze15 wrote:
Mon Jan 18, 2021 11:49 am
...1. I have folded horns curently with a top response of 120hz. For the OT 15, would a 100-110 hz XO seem pretty smooth? Building with the 3015. It seems it comes into its wheel house around 120 or so. The -3db point would be just about 120hz as I see it. Where are you guys crossing your OT12 and 15s to the subs?
I don't have any personal experience with the OTops. But, being a charts and numbers guy myself, I've come to realize there's not usually a one-and-done solution. The guys have been saying it for years and my scientific based mind didn't want to concede, but in the end it really boils down to "how does it sound". If it were me, I'd do exactly as you're doing. Prepare and plan. Then, try all the variations out and see if one combination stands out as better or worse.

You'll likely be fine crossing the OT15 anywhere in the range you're looking at.
Last edited by Seth on Mon Jan 18, 2021 7:09 pm, edited 1 time in total.
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

Bruce Weldy
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Re: OT15 - XO to sub and nominal gain?

#4 Post by Bruce Weldy » Mon Jan 18, 2021 4:01 pm

I high pass my OT12s at 125hz and low pass my subs at 118hz. This helps alleviate some of the build-up at the crossover point. Don't have a chart or analysis to back it up.....just tried it....it worked....been that way for years now....

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
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."

burnsze15
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Re: OT15 - XO to sub and nominal gain?

#5 Post by burnsze15 » Mon Jan 18, 2021 5:17 pm

Bruce Weldy wrote:
Mon Jan 18, 2021 4:01 pm
I high pass my OT12s at 125hz and low pass my subs at 118hz. This helps alleviate some of the build-up at the crossover point. Don't have a chart or analysis to back it up.....just tried it....it worked....been that way for years now....
Thanks Bruce great info. What slopes?

burnsze15
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Joined: Wed Nov 12, 2014 2:44 pm

Re: OT15 - XO to sub and nominal gain?

#6 Post by burnsze15 » Mon Jan 18, 2021 5:18 pm

Thanks for the info.


If anyone can confirm the cabinet gain being about average 5-6db over raw driver spec from 150-1000hz, I would appreciate it. Just want to ensure Im analyzing the charts correctly and apples to apples

Bruce Weldy
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Re: OT15 - XO to sub and nominal gain?

#7 Post by Bruce Weldy » Mon Jan 18, 2021 7:11 pm

burnsze15 wrote:
Mon Jan 18, 2021 5:17 pm
Bruce Weldy wrote:
Mon Jan 18, 2021 4:01 pm
I high pass my OT12s at 125hz and low pass my subs at 118hz. This helps alleviate some of the build-up at the crossover point. Don't have a chart or analysis to back it up.....just tried it....it worked....been that way for years now....
Thanks Bruce great info. What slopes?
LR24 on both....

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
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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Seth
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Re: OT15 - XO to sub and nominal gain?

#8 Post by Seth » Mon Jan 18, 2021 7:12 pm

Here's the trace for a 3015 in an OT15

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

himhimself
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Location: Bloomington IN

Re: OT15 - XO to sub and nominal gain?

#9 Post by himhimself » Mon Jan 18, 2021 7:53 pm

Set my x-over points with a gap like Bruce although a little lower. I think 105 and 115, but not 100% sure and the driverack is buried in the trailer right now. I have T30s on the bottom, not Titans. I used the steepest slopes my PA2 has. Seems to keep the x-over range clean and clear. Play with it and see what sounds good to you, using some material that you are super familiar with.
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

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