T-48 best driver?

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singtall
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T-48 best driver?

#1 Post by singtall »

I think I'm gonna build four T-48's and I'm just wondering if anyone knows what is the absolute best 15" speaker that can be installed in the cabinet?

also, which four tops would you suggest to match?

for live PA system mixing rock/metal. some outdoor gigs with 300-400 people possible.

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Seth
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Re: T-48 best driver?

#2 Post by Seth »

3015LF is the go to driver for that design. There are others that have a very slight edge in peak output, but at the cost of either weight or money. The LAB15 weighs considerably more and might give you 1dB more output at the limit, barely noticeable. (hint: if you're constantly on the limiter, you need to build more cabs.) The 18Sound 15NLW9300 is nearly double the cost of the 3015LF and there may or may not be any noticeable gain in output capability.

Probably best to go with Omni Top 12's with those, unless you're a skilled woodworker with patience... DR200 or DR250

What size venues do you play? Indoors/outdoors?
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

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Seth
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Re: T-48 best driver?

#3 Post by Seth »

Another thing to take into consideration and shop for is a loudspeaker management system, like a dbx Driverack. It will keep you from blowing drivers and allow you to tune your system with built in EQ, Crossovers, and more.
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: T-48 best driver?

#4 Post by Grant Bunter »

singtall wrote: Sun Mar 21, 2021 9:08 pm I think I'm gonna build four T-48's and I'm just wondering if anyone knows what is the absolute best 15" speaker that can be installed in the cabinet?

also, which four tops would you suggest to match?

for live PA system mixing rock/metal. some outdoor gigs with 300-400 people possible.
Depends.
If money is no object, and you can get them, in a T48 the 15" driver with the greatest displacement voltage limit (you'll get used to that term), and hence the greatest output, is the 18Sound 15NLW 9300
Next down from that is the Eminence 3015lf, or, for a similar output and voltage limit, the Lab15. as mentioned by Seth.
The Lab15 has a weight penalty compared to the other 2 drivers I mentioned, and the Lab15 costs a fair bit more than the 3015lf, and the Lab15 is a little less than 18sound.

I agree with the Otop12's, or the DR's. and the driverack...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

jemo1234567890
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Re: T-48 best driver?

#5 Post by jemo1234567890 »

If I would have time in the future (and a little money left over) it tickles in my fingers to build a double Lab12 loaded Titan48.
I know it's a waste of efficiency per driver because you build the narrow width for each driver and have the highest costs per cab and a very heavy Titan48 but with this option I would have the most displacement for each cab.
Like a double loaded T60 but not as low as the T60 but the most bang in the upper bandwidth.

But first step by step my two Otops8 and four T39 with 3012lf :P

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Seth
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Re: T-48 best driver?

#6 Post by Seth »

Grant Bunter wrote: Mon Mar 22, 2021 2:42 am If money is no object, and you can get them, in a T48 the 15" driver with the greatest displacement voltage limit (you'll get used to that term), and hence the greatest output, is the 18Sound 15NLW 9300
Now that you mention it, I seem to recall a conversation about the 18Sound 15NLW9300 and Bill saying that they measure and rate their Xmax in a way that is conservative compared to how Eminence rates their drivers. And with an 80 volt limit, all else being equal, could/should have about a 2.5dB advantage in maximum output over the 3015LF.






Singtall,

To put that into perspective, perceived volume is somewhat subjective. Each person has a different perception of what double or half a given volume is. What's generally accepted as twice as loud is a10dB measured increase. 1dB is a perceivable increase when playing single tones and comparing A:B, but not so easily perceptible in listening to actual musical content. A crowd isn't likely to notice if you increase or decrease the PA's output by 1dB in the middle of a song. Where a 3dB change would likely be noticed by some, depending on how abruptly the change was made.

To achieve a 3dB increase, it takes twice the power. +6dB 4x the power, 9dB = 8x
A 10dB increase requires 10x the power
A 13dB increase requires 20x the power
A 20dB increase requires 100x the power
A 23dB increase requires 200 x the power
A 30dB increase requires 1000 x the power
A 33dB increase requires 2000 x the power
36dB... 4000 x the power... And so on... If your starting figure was one watt and you wanted a 39dB increase, it would take 8000 watts.




Every doubling of cab count gives you an increase of 6dB (generalized breakdown; +3dB for doubling the radiating plane area and +3dB for doubling the system power)
For instance, if you built 24" wide, 3015LF loaded, T48's you'd have the following result for one, 2, 4, and 8 cabs... at 1, 2, 4, and 8 watts total system power, measured at a distance of 1 meter outdoors.
Image

Some people like to look at the average sensitivity, but I prefer to base my calculations on the point of the lowest sensitivity within the target bandwidth. Between 40Hz and 125Hz, the lowest point is 40Hz. So, that's what I base everything on. Whether you EQ your system flat or with a boost on the bottom end, it's that frequency that will limit the overall volume your system can attain without engaging the limiter. That assumes you're actually playing content that low. If you're not DI-ing your bass player and just mic-ing his cab, chances are there's not going to be much down there anyway, which potentially means you can get more out of the complete system, at the expense of not fully utilizing what the cab is capable of... Which then leads into a conversation of using the T39, which in my experience is very worthy of covering your needs as well, even with DI'd bass guitar. But, that's another conversation.

Anyway, back to the point...

Cabs are typically measured at one watt at a distance of one meter (3.3 feet) in half-space unless otherwise noted. Half-space is typical outdoor conditions where there are no boundaries to the propagation of soundwaves other than the ground (picture outer space kind of space, with a floor so sound energy can't propagate downwards). For every doubling of cabs you get +6dB. For every doubling of distance you get a -6dB reduction in volume. Indoors, with the mouth of the sub aimed at a wall +6dB (requires half the amount of cabs as outdoors for to create same output(or the same amount of cabs but at 25% of the required outdoor power)), indoors aimed in a corner +12dB.

Putting all this together, you can calculate your actual cab count and power needs for a given venue and whether or not you think the additional 2.5dB premium the 18Sound driver offers is worth the additional cost of the drivers as well as the additional cost of the amps to drive them (800 watts per cab with the 18Sound driver vs. 450 with the 3015LF). 4 cabs is 3200wats to get only 2.5dB more output than 1800 watts with the 3015LF drivers. That's a lot of amplifier money for 2.5dB. But, if your pack space is more limited than your cash, it could make sense.

Just to clarify, that 2.5dB is not cumulative. It's not +2.5dB per cab, +10dB for 4. It's +2.5dB no matter how many cabs you use, period.

4 24" cabs penciled out assuming a wood cost of $100 per cab looks like this...
Wood, 18Sound drivers, 800wpc amp = roughly $4000 (give or take) for a maximum output of 138dB at 40Hz at 1M outdoors.
Wood, 3015LF drivers, 450wpc amp = a little below $2000 for a maximum output of 135.5dB at 40Hz at 1M outdoors.

Add a v-plate? Add 3dB to that figure for an extra $30.
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: T-48 best driver?

#7 Post by Grant Bunter »

Other than Seth's excellent essay above lol;

If you're looking to eke every last drop out of any build in terms of output, you should probably think about more subs from the outset...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

singtall
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Re: T-48 best driver?

#8 Post by singtall »

Though the cost per driver isn't much more, the cost per amplifier is. I'm thinking that I'm gonna stay with the recommended 3015lf and build at least 4 to start with.

the omni tops look like a decent easy build. i did look at the DR series but wasn't sure which one would pair the best with the sub. I'm also looking at things like total cabinet height with the top stacked on top of the sub. I'm a fairly skilled woodworker and I also build guitars, so I'm not afraid of a complex build if it's the far superior solution. I may build some omni 12's for small clubs and look at building the bigger DR for outdoor gigs.

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Seth
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Re: T-48 best driver?

#9 Post by Seth »

singtall wrote: Mon Mar 22, 2021 7:04 pm I'm also looking at things like total cabinet height with the top stacked on top of the sub.
I know you see this done all over the place and even big companies advertise systems set up this way... It sells products, but 95% of the time it's the worst location for a subwoofer. Better to put the subs where they work well and put the tops on tripods.

Here's a quick read that speaks to the subject; Rules for Subwoofer placement and stacking
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

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Re: T-48 best driver?

#10 Post by Grant Bunter »

singtall wrote: Mon Mar 22, 2021 7:04 pm Though the cost per driver isn't much more, the cost per amplifier is. I'm thinking that I'm gonna stay with the recommended 3015lf and build at least 4 to start with.

the omni tops look like a decent easy build. i did look at the DR series but wasn't sure which one would pair the best with the sub. I'm also looking at things like total cabinet height with the top stacked on top of the sub. I'm a fairly skilled woodworker and I also build guitars, so I'm not afraid of a complex build if it's the far superior solution. I may build some omni 12's for small clubs and look at building the bigger DR for outdoor gigs.
Fair call on the subs plan.

Otops or DR's. It's always been said, if you can build DR's then do so. They are not a quick build for most people. Not extraordinarily difficult, just take a lot of time. There's lots of pieces making the whole, but man they sound great!
Tin tacks, DR250's are a couple of dB louder per cab than Otop12's. Otop12's will stack flat, DR's are splayed angled so can be used for J arraying. Otops12's can utilize a better more expensive compression driver, allowing a lower crossover point. DR's can't use that same CD until you get to the DR280.
Once you go past DR250''s (which I can handle by myself), you need crew, so DR280's and 90's. 300's are concert tops, so have a minimum audience capacity way beyond your expectation of crowd size at this time.
I think DR250's would be fine for you if you went with DR's.

Build 2 different lot's of cabs? Nah. Make a decision, stick with it. You can always turn down, even using 1 mains a side. If you're going to invest more build time though, make it the same to upscale your system I reckon...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Seth
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Re: T-48 best driver?

#11 Post by Seth »

In regards to the DR vs OT12 considerations, I'll add to Grants excellent input... It's been my understanding that the OT12 and DR200 are roughly equivalent to each other in output. The sales page lists recommended audience sizes per cab count at the bottom of the page and has the same recommended audience size per cab count for both of these designs. The DR250 has a higher audience size rating for 2 & 4 cabs, but all three options share the same recommended audience size for 6 & 8 cabs, of 1200 and 2000 people.

The DR200 is the lightest and least expensive option and can be built for about $175 each with the base driver. The premium recommended driver is no longer in production, so it's pretty much limited to the Beta 8 or searching for other drivers within the allowable spec range.

The DR250 has more driver options available, a higher average sensitivity than the other two options, and higher power handling than the DR200. But cost, weight, and size is slightly more than the DR200.

The OT12 is an easy straight forward build, weighs more than a DR200 and less than a DR250, has the lowest cab height of all three designs, and can be built in the light weight "J" Array version.


I have chosen to go the route of building 8 DR200's (4 initially and I have not assembled them yet), Grant has DR250's, and Bruce has OT12's. I think the right answer for you will be any one of those cabs based on the little differences and how they fit in your plan and personal values. I value light weight and low cost. I'm not sure why Grant and Bruce chose what they chose. But, I imagine Grant valued the additional output of the 250 and didn't mind the cost/size/weight difference and Bruce probably preferred a quicker, less intricate build.

Something to add is, in the case of all three designs, it's been noted several times over the years that using them in stacks of at least two per side, even when the gig doesn't require them for additional output, helps smooth out the response and creates a noticeable improvement to the overall sound quality. So, whatever design you choose, consider building at least 4 of them to take advantage of that benefit.

Here's an interesting thread comparing some of the cabs: DR-200-250 A/B



I could see building a couple Omni's or Jacks for small pub gigs. Alternatively, I could also see using whatever top you choose for the big rig with a more compact sub in those cases, as an option too... A slim 12" (or even 10") loaded T39, corner loaded. Lots and lots of different possible configurations depending on what your vision is. My current small gig/rehearsal rig is a 16" wide 3012LF loaded T39 and two 2x6 SLA Pro's. It's a potent little package, the 2x6 cabs don't block a whole lot of stage/crowd view, and the whole package is quite portable.
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: T-48 best driver?

#12 Post by Bruce Weldy »

Seth wrote: Tue Mar 23, 2021 12:22 pm I'm not sure why Grant and Bruce chose what they chose.
I was looking at all the designs while I was building my first two T39s. But one day, one of the authorized builders from Ohio put up some OT12s for sale. I figured that would get my system up and running faster, so I bought two from him. Cost me about the same that I would have spent building them and they had the 1.2 crossover option in 'em. So, timing and expediency determined my path more than chart-reading and hand-wringing.

That said, I've been really happy with the OT12s. I later built two more - this time with the melded array, which goes on the bottom and the CD version on top. I always use two per side for the coupling. They really sound great and get kudos all the time for the great vocal reproduction. I've come to really like the fact that they are square and stack great in the trailer. I'd have to totally re-think packing with DRs due to the angles.

I've done dozens (hundreds?) of shows over the last ten years with these boxes and have never regretted the decision. I'm sure Grant would say the same about his DR250s.

In fact, just got the go ahead to provide sound again this year for our local Concerts in the Park. 6-T39s and 4 OT12s handle the crowd of 500 outside quite nicely. It's been a year since my trailer has left the driveway....

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."

himhimself
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Re: T-48 best driver?

#13 Post by himhimself »

Seth wrote: Tue Mar 23, 2021 12:22 pm Something to add is, in the case of all three designs, it's been noted several times over the years that using them in stacks of at least two per side, even when the gig doesn't require them for additional output, helps smooth out the response and creates a noticeable improvement to the overall sound quality. So, whatever design you choose, consider building at least 4 of them to take advantage of that benefit.
+1
I built 4 otop j-arrays. The simplicity of the otop build, the trapezoid design like the DRs, and light weight. Two per side can do amazing things. I'm building a third and fourth T30 (3012LF) to hopefully keep up with the tops, and I only have Beta-12s, not the premium drivers. I went with the piezos. I'm sure the CDs could sound even better, but without A-B'ing, I'm very happy with my melded-straight sets. And the cost was easy.
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

Grant Bunter
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Re: T-48 best driver?

#14 Post by Grant Bunter »

Seth wrote: Tue Mar 23, 2021 12:22 pm I'm not sure why Grant and Bruce chose what they chose. But, I imagine Grant valued the additional output of the 250 and didn't mind the cost/size/weight difference and Bruce probably preferred a quicker, less intricate build.
In my case it was quite simple:
Build DR's if you can. "I'll give that a crack".
On the sales page it says something like: The DR250 is the flagship of the DR's. "So let's have a crack at the flagship"
:)

The extra output was a bonus, the mid woofer was cheaper for a DR250 than for a Otop12, and I was finding ply pretty cheaply at that time...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Grant Bunter
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Re: T-48 best driver?

#15 Post by Grant Bunter »

singtall wrote: Mon Mar 22, 2021 7:04 pm 3015LF
Hey, don't know where you live, but if you're anywhere near Des Moines Iowa, there's 4 x 30" wide 3015lf loaded T48's for sale in the For Sale section.
You probably couldn't build yours for the asking price from the seller...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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