OmniTop 15 vs Jack 15 lowest distortion

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Bens-Alley
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OmniTop 15 vs Jack 15 lowest distortion

#1 Post by Bens-Alley » Fri May 07, 2021 10:58 pm

I’ve purchased OmniTop 15 plans and have my drivers but before I build I wanted to ask this question:

Between the OmniTop 15 and the Jack 15, which has the lowest distortion at low and high output levels? I will be running the cab from 100Hz up to 700Hz and using dsp to crossover. Ultimate output is not really an issue as they looked very close on the SPL charts here on the forum.


Just curious before I build as I could always purchase Jack 15 plans.

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Seth
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Re: OmniTop 15 vs Jack 15 lowest distortion

#2 Post by Seth » Fri May 07, 2021 11:55 pm

Interesting question, and I see why the curiosity occurred.



I don't know.
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

Grant Bunter
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Re: OmniTop 15 vs Jack 15 lowest distortion

#3 Post by Grant Bunter » Sat May 08, 2021 12:53 am

Hi and welcome :)

Both are horn designs, so will naturally filter harmonics to some extent, meaning neither will particularly exhibit distortion at low volumes.

High output volume distortion is a different story though.
The following quote is from an old version of the J15 plans. I'm not sure if it's in more current plans.
Low frequency power capacity is determined by the driver excursion limit, xmax. The 3015 has 5.9mm xmax, so it has the highest distortion free displacement limited power handling at 350 watts. At 4.0mm xmax the Kappa 15 will take 150 watts without reaching excursion limits; the 2515 with 4.8mm xmax will handle 200 watts.
Since all those drivers are also recommended for the Otop15 (at least in my older plans for them), the answer to your question is driver dependant, not design dependant.

I reckon J15's loaded with 3015's is the answer.

What drivers did you buy?

The next questions are also important.
What tops are you using that don't cover down to 100Hz adequately now?
Kick bins by and large mostly disappeared not long after the dinosaur sub cabs in the 70's.
Why are you thinking kick bins?

Otop 15's (and Jack 15's) will adequately cover from 100Hz all the way through to the top of HF if you build them as per plans
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

Bens-Alley
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Re: OmniTop 15 vs Jack 15 lowest distortion

#4 Post by Bens-Alley » Sat May 08, 2021 3:43 am

Thanks for input. To answer your driver question, I’m using FaitalPRO 15PR400’s. They are good for 5.75mm of Xmax so they will do just fine. Got a great deal on them last year then life got in the way before I could start my original OmniTop build.

I might just go ahead and order a set of Jack 15 plans anyways.

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Bill Fitzmaurice
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Re: OmniTop 15 vs Jack 15 lowest distortion

#5 Post by Bill Fitzmaurice » Sat May 08, 2021 7:45 am

If you're only using them above 100Hz build the OTop, it has better midrange and the box is smaller. The main difference between the J15 and OTop 15 is that the larger box size of the J15 allows larger port area, to prevent low frequency chuffing. Since the OTop 15 is intended for use with subs low frequency port chuffing isn't a concern. Distortion isn't a factor, either is cleaner than any direct radiating 115. As to why you're only running them to 700Hz, I can't think of a logical reason for that.

Bens-Alley
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Re: OmniTop 15 vs Jack 15 lowest distortion

#6 Post by Bens-Alley » Sat May 08, 2021 1:07 pm

700Hz is the lowest my compression driver can go and it sounds amazing down to there so I know I have that range covered if need be. I was curious what I was looking at from that range down. I have active crossovers so I will definitely be playing around with the crossover and can cross higher easily.

Thanks Bill! The forum is a big help as well 👍

Bruce Weldy
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Re: OmniTop 15 vs Jack 15 lowest distortion

#7 Post by Bruce Weldy » Sat May 08, 2021 1:34 pm

Bens-Alley wrote:
Sat May 08, 2021 1:07 pm
700Hz is the lowest my compression driver can go and it sounds amazing down to there so I know I have that range covered if need be. I was curious what I was looking at from that range down. I have active crossovers so I will definitely be playing around with the crossover and can cross higher easily.

Thanks Bill! The forum is a big help as well 👍
Just being curious.....are you looking to put your compression driver in an OTop15 using the diffraction horn in the plans? Or, do you have a separate enclosure for that?

I like the lower crossover point also. I use the passive crossover in the plans along with the horn in the plans and have a 1.2khz highpass on the horn.

Any reason for the 15 over the OTop 12? It handles 100hz with no problem and is a lot smaller and lighter.

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."

Bens-Alley
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Re: OmniTop 15 vs Jack 15 lowest distortion

#8 Post by Bens-Alley » Sun May 09, 2021 2:53 pm

Had the 15” drivers already from an open baffle HiFi project that didn’t happen. Ordered the OmniTop plans and the specs worked in the cab. The 15” cab gives me lots of overlap with the sub and definitely plenty of overlap with my compression driver. This is definitely more of an experiment than anything else and I love to build things. I do plan on putting the compression driver horn on top for now to play around.

Bruce Weldy
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Re: OmniTop 15 vs Jack 15 lowest distortion

#9 Post by Bruce Weldy » Mon May 10, 2021 7:56 am

Bens-Alley wrote:
Sun May 09, 2021 2:53 pm
Had the 15” drivers already from an open baffle HiFi project that didn’t happen. Ordered the OmniTop plans and the specs worked in the cab. The 15” cab gives me lots of overlap with the sub and definitely plenty of overlap with my compression driver. This is definitely more of an experiment than anything else and I love to build things. I do plan on putting the compression driver horn on top for now to play around.
got it.....have fun with it.

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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