1.2 vs 1.8 crossover? pros and cons

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burnsze15
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Re: 1.2 vs 1.8 crossover? pros and cons

#16 Post by burnsze15 » Mon May 04, 2020 5:34 pm

Here’s a question, has anyone loaded a driver like a B&C DE990TN or the new Em 314TX on the horn to achieve a 700-800Hz Xover point to put more of the vocal in the horn? Not sure how one would load on the horn of the Ot12 With a high power capacity and lower crossover, combined with a doible 3012HO would be pretty interesting in terms of output capability per cab. If the CD loaded on the horn my guess is that horn design is too small to yield any directivity below 1.2 anyhow and things would go omni.

Anyway food for thought?

Aside from the lower XO, if you put a high output driver like the 990 on the horn at 1.2 and a pair of 3012HOs what would that output look like per cab? I bet pretty damn amazing? Yes cost goes up to 780$ in drivers alone per cab.

Grant Bunter
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Re: 1.2 vs 1.8 crossover? pros and cons

#17 Post by Grant Bunter » Mon May 04, 2020 6:03 pm

burnsze15 wrote:
Mon May 04, 2020 5:34 pm
Here’s a question, has anyone loaded a driver like a B&C DE990TN or the new Em 314TX on the horn to achieve a 700-800Hz Xover point to put more of the vocal in the horn? Not sure how one would load on the horn of the Ot12 With a high power capacity and lower crossover, combined with a doible 3012HO would be pretty interesting in terms of output capability per cab. If the CD loaded on the horn my guess is that horn design is too small to yield any directivity below 1.2 anyhow and things would go omni.

Anyway food for thought?

Aside from the lower XO, if you put a high output driver like the 990 on the horn at 1.2 and a pair of 3012HOs what would that output look like per cab? I bet pretty damn amazing? Yes cost goes up to 780$ in drivers alone per cab.
In which cab are you talking about?
Like every half decent cab in the world, Bill's designs are based on TS parameters, modelling, custom filters, and size of components.
So, your suggestion would require knowing what will fit size wise for a CD in a particular cab, a total redesign of the custom filters to cater for the lower filter point etc etc.
The DR250 already averages 106dB @1W/1M, the Otop 12 not much lower. There's not a lot on the market that beats that.

The suggestion of spending nearly $800 per cab in drivers is almost the antithesis of DIY as well.
The goal here is cheap cabs that you can build yourself, that perform amazingly, for as little cost as possible.

And that's achievable using the components listed in the 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...

burnsze15
Posts: 43
Joined: Wed Nov 12, 2014 2:44 pm

Re: 1.2 vs 1.8 crossover? pros and cons

#18 Post by burnsze15 » Mon May 04, 2020 6:13 pm

Got it thanks! I digress. Just threw it out there for discussions sake.

Grant Bunter
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Re: 1.2 vs 1.8 crossover? pros and cons

#19 Post by Grant Bunter » Mon May 04, 2020 10:11 pm

burnsze15 wrote:
Mon May 04, 2020 6:13 pm
Got it thanks! I digress. Just threw it out there for discussions sake.
It's all good!
Sorry, I see now you're asking in regards to an Otop 12.
Seriously, the B&C CD is only 1dB 1W/1m higher in sensitivity than the premium recommended NSD2005, which not long ago was replaced with another driver.
So if you want to check out the specs for both, you'll know if the B&C will fit, but I don't think so.
Given the above also, you probably wouldn't need 2 x 3012HO's to keep up...
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...

burnsze15
Posts: 43
Joined: Wed Nov 12, 2014 2:44 pm

Re: 1.2 vs 1.8 crossover? pros and cons

#20 Post by burnsze15 » Fri May 29, 2020 6:25 am

Thanks for the feedback gang. I’m really just exploring ALL possibilities before I invest in a build.

I guess my thoughts on high sens/high power handling capable drivers is merely attainable clean output. So if you had a 3012HO that is capable of 800w program and 99db say, and you had a 12NDL88 thats equally as sensitive and can handle 1400w program at 98db sens, combined with a driver like a B&C 1” or 1.4” which has 108db sens and 200-220w program capability, the overall total output of each cab would increase with no decrease in quality, thus maximizing the sound per dollar/minute ratio invested in the array. Its basically taking the OT12 to its ultimate capability maximizing its excellent cost/perf ratio even with the increased cost of the drivers. If each cab was 5db more capable on the books, then an entire 6-8 cab array would be that much more capable and have that much more headroom. The comprimise is increase in driver cost, probably about 100$ per cab from the NSD replacement to and HO to these more capable drivers.

Anyway, having said all that, the design is amazing as is and those drivers surely match the big bang for the buck ratio as is, and its very respectable.

Grant Bunter
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Location: Ilfracombe Queensland Australia
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Re: 1.2 vs 1.8 crossover? pros and cons

#21 Post by Grant Bunter » Fri May 29, 2020 7:22 am

burnsze15 wrote:
Fri May 29, 2020 6:25 am
Thanks for the feedback gang. I’m really just exploring ALL possibilities before I invest in a build.

I guess my thoughts on high sens/high power handling capable drivers is merely attainable clean output. So if you had a 3012HO that is capable of 800w program and 99db say, and you had a 12NDL88 thats equally as sensitive and can handle 1400w program at 98db sens, combined with a driver like a B&C 1” or 1.4” which has 108db sens and 200-220w program capability, the overall total output of each cab would increase with no decrease in quality, thus maximizing the sound per dollar/minute ratio invested in the array. Its basically taking the OT12 to its ultimate capability maximizing its excellent cost/perf ratio even with the increased cost of the drivers. If each cab was 5db more capable on the books, then an entire 6-8 cab array would be that much more capable and have that much more headroom. The comprimise is increase in driver cost, probably about 100$ per cab from the NSD replacement to and HO to these more capable drivers.

Anyway, having said all that, the design is amazing as is and those drivers surely match the big bang for the buck ratio as is, and its very respectable.
Yep, I understand.
The thing is, these mains/tops are horns too, so that increases sensitivity. So, as loud as, or louder than, the same drivers in direct radiators, with less power to get there.
There's a kinda saying here;
It's not the driver(s), it's the design, that dictates response.

Like any design, there are limits. So the next thing that's said here, is;
If you're pushing your cabs to their limit, you need to build more cabs.
Each doubling of cabs adds +6dB. You can double the cab count for well under the cost of the drivers you've mentioned.

It's sometimes a huge leap of faith to build these designs, but, can I respectfully say, if you haven't ever heard these cabs in RL, don't think about ways to "improve" them from the get go. Let us know where you are. We might be able to point you to a fellow builder for a demo, local suppliers, gigs etc, to try and help out...
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...

himhimself
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Location: Bloomington IN

Re: 1.2 vs 1.8 crossover? pros and cons

#22 Post by himhimself » Fri May 29, 2020 7:55 pm

It's sometimes a huge leap of faith to build these designs, but, can I respectfully say, if you haven't ever heard these cabs in RL, don't think about ways to "improve" them from the get go. Let us know where you are. We might be able to point you to a fellow builder for a demo, local suppliers, gigs etc, to try and help out...
+1 !!!
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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Tom Smit
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Re: 1.2 vs 1.8 crossover? pros and cons

#23 Post by Tom Smit » Sat May 30, 2020 1:15 pm

Grant Bunter wrote:
Fri May 29, 2020 7:22 am
Each doubling of cabs adds +6dB. You can double the cab count for well under the cost of the drivers you've mentioned.
Not only that, but you also get smoother response (bonus!)
TomS

Mikesummers
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Re: 1.2 vs 1.8 crossover? pros and cons

#24 Post by Mikesummers » Mon Mar 08, 2021 5:03 pm

Jumping in...i am planning to build an OTop12 (one) to try it out. Sounds like most folks think the 1.2k xover sounds best. I assume that is built with the recommended F151M8? So 2 questions about that driver. Recommended xover is 1.8k, useable range is 1.8k-20k...no worries? Also the response curve takes a hard dive above 10k. ??

I know, it has always been thus and it probably works fine...just askin. Home hifi application, fyi
Thx

Bruce Weldy
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Re: 1.2 vs 1.8 crossover? pros and cons

#25 Post by Bruce Weldy » Mon Mar 08, 2021 5:34 pm

Mikesummers wrote:
Mon Mar 08, 2021 5:03 pm
Jumping in...i am planning to build an OTop12 (one) to try it out. Sounds like most folks think the 1.2k xover sounds best. I assume that is built with the recommended F151M8? So 2 questions about that driver. Recommended xover is 1.8k, useable range is 1.8k-20k...no worries? Also the response curve takes a hard dive above 10k. ??

I know, it has always been thus and it probably works fine...just askin. Home hifi application, fyi
Thx
The reason that you can cross lower than the specs is that they typically spec with a 12db slope. Bill's design has a much steeper slope thus giving you more usable frequency.

I love the 1.2k crossover......I haven't used the F151. I built mine with the NSD2005 before it was discontinued.

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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