Conversion of 30" T39 Dual 3012 LF to Single

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Richness
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Conversion of 30" T39 Dual 3012 LF to Single

#1 Post by Richness » Sat May 26, 2018 2:06 am

Good day. My previous carry space manipulated my decision of building 2 Dual 30" T39s. I now want to convert them to Single. Would it be retarded to simply remove one speaker then use the cut out that i kept and PL / Screw to cover up the hole? This would mean that the single sub would now be off to one side and not in the middle. Would I loose performance by not having the sub in the middle of the baffle or is there a better and easy way to convert?


Thanks in advance.
2xT39 30'' 3012LF Dual
1xT39 38" 3012LF Dual

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Bill Fitzmaurice
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#2 Post by Bill Fitzmaurice » Sat May 26, 2018 8:11 am

There's no need to have the driver centered on the baffle.

Richness
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#3 Post by Richness » Sat May 26, 2018 2:07 pm

Awesome thanks Mr. Fitzmaurice. Additionally, would I still be able to crossover at 40hz when using the 2 singe loaded 30" T39 or would it now have to be 45hz? And the final question for now..... I will eventually have 2 Single loaded 30" and 2 dual loaded 38" T39 (38" dual is sweet). What tops would u recommend? I wanna get plans but not sure which. I was looking at OT12 but I would prefer dual compression drivers, as far as I read these are only single. I am scared about the build difficulty of the DRs. The OT8 looks solid and I would only use them coupled with subs. I was worried about the low mids performance of an 8". Suggestions?
2xT39 30'' 3012LF Dual
1xT39 38" 3012LF Dual

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Bill Fitzmaurice
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#4 Post by Bill Fitzmaurice » Sat May 26, 2018 2:54 pm

You'll be OK with 40Hz due to the width of the cabs. There's no advantage to using dual compression drivers in the OTop 12, if there was I'd have made it that way. DR200 would have been OK with one HF driver but there was no way to fit a single driver HF horn to that cab.

Bruce Weldy
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#5 Post by Bruce Weldy » Sat May 26, 2018 3:16 pm

Richness wrote:
Sat May 26, 2018 2:07 pm
I would prefer dual compression drivers,
Interested in why you'd want dual drivers.....with the exception of high-end line arrays, I can't think of a single box out there with dual drivers (with the exception of a few that use cheap drivers on a manifold). One good driver mates up perfectly with the 12 inch in the OT12.

Use the NSD2005 - it gives you a lower crossover point than the ASD1001. A little more expensive, but sounds better. Stack two OT12s per side and you get a really smooth sounding PA and you get your two drivers.

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."

Richness
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#6 Post by Richness » Sat May 26, 2018 4:28 pm

Thanks for replies. Bruce... I heard OT15 with dual ASD 1001 and liked the throw distance of the highs but maybe my knowledge is limited as the dual being the reason for the clarity at 75 feet.

Bill - I was not in any any way questioning the design but wanted to know if a dual was probably in the plans and I didn't read it in description. (deciding on which plans to buy). The OT8 and 15 has a dual option so I thought maybe I missed something. Thanks

Bruce.... I noticed in your sig that u had 4 OT12 Melded Array/NSD. Do u use one melded for closer and wider coverage and stack the NSD ON on top on each side for the distance? This is the approach I was thinking about.
Last edited by Richness on Sat May 26, 2018 8:34 pm, edited 1 time in total.
2xT39 30'' 3012LF Dual
1xT39 38" 3012LF Dual

Grant Bunter
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#7 Post by Grant Bunter » Sat May 26, 2018 4:46 pm

Richness wrote:
Sat May 26, 2018 2:06 am
Good day. My previous carry space manipulated my decision of building 2 Dual 30" T39s. I now want to convert them to Single. Would it be retarded to simply remove one speaker then use the cut out that i kept and PL / Screw to cover up the hole? This would mean that the single sub would now be off to one side and not in the middle. Would I loose performance by not having the sub in the middle of the baffle or is there a better and easy way to convert?


Thanks in advance.
You're not really doing much to increase output if your plan is to "rob" a driver from each dual loaded 30" wide cab to build a second dual loaded 38" wide cab. By the time you add up the +'s and -'s of doing that, output will be much the same.

Seems like you want to build another cab, buy new drivers for that cab. Use all 4, and that will increase subs output.

You might like to edit your last post, as nice a guy as he is, Bruce is not Grant, and Bruce has the Otops...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
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...

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Bill Fitzmaurice
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#8 Post by Bill Fitzmaurice » Sat May 26, 2018 4:47 pm

The OT8 and OT15 are taller cabs, so they need dual drivers so they're not spaced too far apart.

Richness
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#9 Post by Richness » Sat May 26, 2018 8:51 pm

Grant Bunter wrote:
Sat May 26, 2018 4:46 pm
Richness wrote:
Sat May 26, 2018 2:06 am
Good day. My previous carry space manipulated my decision of building 2 Dual 30" T39s. I now want to convert them to Single. Would it be retarded to simply remove one speaker then use the cut out that i kept and PL / Screw to cover up the hole? This would mean that the single sub would now be off to one side and not in the middle. Would I loose performance by not having the sub in the middle of the baffle or is there a better and easy way to convert?


Thanks in advance.
You're not really doing much to increase output if your plan is to "rob" a driver from each dual loaded 30" wide cab to build a second dual loaded 38" wide cab. By the time you add up the +'s and -'s of doing that, output will be much the same.

Seems like you want to build another cab, buy new drivers for that cab. Use all 4, and that will increase subs output.

You might like to edit your last post, as nice a guy as he is, Bruce is not Grant, and Bruce has the Otops...


So sorry ....fixed names.

Wouldn't 2 dual 38" and 2 single 30"s be noticeably louder than 2 dual 30"and 1 Dual 38"?

Yes my plan was to keep the same number of drivers and have 2 single 30" and 2 dual 38"s. Let me elaborate on why I wanted to do this. The dual 38" hits much nicer than the 30"s. Also I want to be able to use my 15amp Furman on 1 15A circuit to run the entire rack. I currently have 3 Crown XLS 1502 bridged at 4 ohms for 3 dual boxes. If I will need to run another 2 amps for 4 OT12 then I may now need to have to think about power requirements. Please tell me if my logic is way off. Lol.

I was gonna ask after getting plans but here goes... I am planning on running mids and highs on separate amps. Which Crown XLS would be good for mids in 4 OT12 ran in stereo at 4 ohms and which amp for tweets and or CD Drivers. Yet another question if I decide to do both melded array and ASD for 2 boxes on each side do they crossover at same point and how would I adjust power for their different requirements?
2xT39 30'' 3012LF Dual
1xT39 38" 3012LF Dual

Grant Bunter
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#10 Post by Grant Bunter » Sat May 26, 2018 10:51 pm

Richness wrote:
Sat May 26, 2018 8:51 pm

Wouldn't 2 dual 38" and 2 single 30"s be noticeably louder than 2 dual 30"and 1 Dual 38"?

Yes my plan was to keep the same number of drivers and have 2 single 30" and 2 dual 38"s. Let me elaborate on why I wanted to do this. The dual 38" hits much nicer than the 30"s. Also I want to be able to use my 15amp Furman on 1 15A circuit to run the entire rack. I currently have 3 Crown XLS 1502 bridged at 4 ohms for 3 dual boxes. If I will need to run another 2 amps for 4 OT12 then I may now need to have to think about power requirements. Please tell me if my logic is way off. Lol.

I was gonna ask after getting plans but here goes... I am planning on running mids and highs on separate amps. Which Crown XLS would be good for mids in 4 OT12 ran in stereo at 4 ohms and which amp for tweets and or CD Drivers. Yet another question if I decide to do both melded array and ASD for 2 boxes on each side do they crossover at same point and how would I adjust power for their different requirements?
It isn't absolutely necessary to biamp tops. If you run them all in mono, you can use one side of an amp as a power shade for the melded array cabs, and one for the CD's. With ASD's, the crossover filters in the plans are at the same point as the melded (but with different values component wise).

Subs.
Put it this way. If you elected to build 2 x T39 dual loaded subs at maximum width of 56", you would notice a big difference in output!
Really, a 30" wide dually is the same as 2 x 15" wide singles. 15" wide is the minimum width for a 12" loaded T39, so really, all you have done is built a dual loaded slim.
Even the 38" wide is basically 2 x 19" wide cabs together.
I've noticed a significant change in output when comparing a 20" wide T39, to a 28" wide single.

Noticeably louder is only +3dB. Yes, your plan will make that. But it's not really a lot of return for all the effort involved in modding the 30" cabs and building a new 38" wide cab.

It sound like your carry space has increased. Fill it with a pair of as wide a dual loaded cab you can fit into that space to make some significant moves in output
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
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...

Bruce Weldy
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Location: New Braunfels, TX

Re: Conversion of 30" T39 Dual 3012 LF to Single

#11 Post by Bruce Weldy » Sat May 26, 2018 11:10 pm

Richness wrote:
Sat May 26, 2018 4:28 pm
Bruce.... I noticed in your sig that u had 4 OT12 Melded Array/NSD. Do u use one melded for closer and wider coverage and stack the NSD ON on top on each side for the distance? This is the approach I was thinking about.
That's what I do. However, I like the sound of the NSD better and I don't really need the extra 30 degrees of horizontal dispersion most of the time. But, if you do use the horns, stick with the NSD because of its lower crossover point than the ASDs.

One of these days, I might replace the melded with some more NSDs or build another set of cabs. But, the older I get, the lazier I seem to get........

On another note....just got home from mixing a show on a hired PA. No crossover, just aux fed subs using the EQ on the X32 as a crossover. The subs were running up to 300 and the tops were down to 60......AAARRRRGGGHHHH........fixed that in a hurry. The bottom end cleaned up nicely.

Amazing that someone would set their system up like that.

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."

Richness
Posts: 19
Joined: Mon Dec 04, 2017 10:16 am

Re: Conversion of 30" T39 Dual 3012 LF to Single

#12 Post by Richness » Sat May 26, 2018 11:56 pm

Bruce Weldy wrote:
Sat May 26, 2018 11:10 pm
Richness wrote:
Sat May 26, 2018 4:28 pm
Bruce.... I noticed in your sig that u had 4 OT12 Melded Array/NSD. Do u use one melded for closer and wider coverage and stack the NSD ON on top on each side for the distance? This is the approach I was thinking about.
That's what I do. However, I like the sound of the NSD better and I don't really need the extra 30 degrees of horizontal dispersion most of the time. But, if you do use the horns, stick with the NSD because of its lower crossover point than the ASDs.

One of these days, I might replace the melded with some more NSDs or build another set of cabs. But, the older I get, the lazier I seem to get........

On another note....just got home from mixing a show on a hired PA. No crossover, just aux fed subs using the EQ on the X32 as a crossover. The subs were running up to 300 and the tops were down to 60......AAARRRRGGGHHHH........fixed that in a hurry. The bottom end cleaned up nicely.

Amazing that someone would set their system up like that.

Thanks Bruce. Think I have made up my mind with 4 OT12 with 2512 and NSD. Subs pushing 300hz. Wow. Now that's what I call mid bass. Lol
2xT39 30'' 3012LF Dual
1xT39 38" 3012LF Dual

SethRocksYou
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#13 Post by SethRocksYou » Sun May 27, 2018 2:08 pm

Pretty sure you'd want to build 4 more 30" singles to maximize on the drivers you already have. V-plated, that's a seven and a half foot tall stack.

FWIW, even though all the marketing and comparative graphs state 30" as the widest and most effective single, the new plans state that 28" is the new magic number. Just food for thought.

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Bill Fitzmaurice
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Re: Conversion of 30" T39 Dual 3012 LF to Single

#14 Post by Bill Fitzmaurice » Sun May 27, 2018 3:05 pm

I recommend 28" because that's the actual opening width of 30" doors.

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Re: Conversion of 30" T39 Dual 3012 LF to Single

#15 Post by SethRocksYou » Sun May 27, 2018 6:08 pm

Bill Fitzmaurice wrote:
Sun May 27, 2018 3:05 pm
I recommend 28" because that's the actual opening width of 30" doors.
Interesting, good to know. Thank you Bill. Is there a width that offers absolute optimum results for a single 12?

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