BillFitzmaurice.info

Hi all.

I've been enjoying reading though the forum and picking up such great knowledge from you all.
I'm planning on building two T48 subs with 3015LF driver, 30 inches wide, and then in the future build two more - when I can afford two more drivers

I've read that the T48s are best when loaded against a wall or corner, which makes sense, but how well do they perform outside on their own? ie, before i build an extra two, will just one either side of an outdoor stage have any impact? This is for small gigs - 200 - 300 people, paired with 2000w EV tops. and are aimed at replacing a pair of small front loaded cabs.

cheers!

Matt

Hey Matt, welcome to the party I'm Seth.

Whenever possible, more times than not, it's better to have the Subs grouped together on one side of the stage (or centered in front) than it is to have one one each side. It's even the first thing covered in the Rules for Subwoofer placement and stacking thread.

Are you doing live sound or recorded? What kinda stuff do you like to play?

Thanks Seth!

These will mostly be used for live music, although I also work on a bunch of festivals and small outdoor raves where it's predominantly DJ's playing and I hope that this system will be able to be used on these gigs too. I can see that grouping them together in the middle might be the best way to go, although that's not always practical - nor is putting them together on one side, as a bunch of people on the other side of the stage will just be getting the tops! But yea, I would definitely try grouping them whenever practical.

I play DnB at these same festivals (So I'm typically stage managing, running tech, and then playing a DJ set at some stage over the weekend) so I did consider building tubas for that extra sub extension, but realistically the Titan is going to be more useful for 90% of my jobs.

I guess what I really want to know is: is one T48 going to be better, or worse, than a front loaded mackie sub? if it's no worse then I can deal with that until building a second pair. thanks!

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pm I guess what I really want to know is: is one T48 going to be better, or worse, than a front loaded mackie sub? if it's no worse then I can deal with that until building a second pair. thanks!

Better than Mackie front loaded. Yes.

Better than two Mackies.

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pm...is one T48 going to be better, or worse, than a front loaded mackie sub?...

(engage facepalm)

If you build any of Bill's plans, you're guaranteed to thumb your nose at any consumer grade speakers from then on.

jimbo7 wrote: ↑Tue Jun 15, 2021 11:24 pm

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pm...is one T48 going to be better, or worse, than a front loaded mackie sub?...

(engage facepalm)

If you build any of Bill's plans, you're guaranteed to thumb your nose at any consumer grade speakers from then on.

haha, well yea I figured that It's just reading through forums and people saying stuff like 'one horn loaded sub on it's own wont work' etc etc that made me think twice.

Mattsoniclab wrote: ↑Tue Jun 15, 2021 5:48 pm ...This is for small gigs - 200 - 300 people, paired with 2000w EV tops...

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pm...is one T48 going to be better, or worse, than a front loaded mackie sub?...

Personally, I've used a single 12" 3012LF loaded 16" wide T39 with a pair of QSC K12.2 tops and seemed to run out of bottom the same time the tops started screaming with distortion. My guess is you'll be pleased if you're going to play it/them with a pair of EV tops.

Here's my single 16" T39 in action with the pair of K12.2's at roughly 100' out off stage.

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pmThanks Seth!

These will mostly be used for live music, although I also work on a bunch of festivals and small outdoor raves where it's predominantly DJ's playing and I hope that this system will be able to be used on these gigs too. I can see that grouping them together in the middle might be the best way to go, although that's not always practical - nor is putting them together on one side, as a bunch of people on the other side of the stage will just be getting the tops! But yea, I would definitely try grouping them whenever practical.

I play DnB at these same festivals (So I'm typically stage managing, running tech, and then playing a DJ set at some stage over the weekend) so I did consider building tubas for that extra sub extension, but realistically the Titan is going to be more useful for 90% of my jobs.

If you've got more than enough sub with extra output to spare, split up side to side is okay as long as you have them separated by at least 2 wavelengths distance of the lowest frequency you expect to play. For less than 4 T48's that is roughly 40Hz or 35Hz with 4 or more cabs (clustered together, not 2 per side. 2 per side is still 40Hz). To calculate that distance you divide the speed of sound in feet per second (roughly 1125fps) by the frequency and multiply by 2 (2 wavelengths). 1125fps/40Hz= 28.125 foot wavelength x2= 56.25... the subs need to be separated 56'3" for best results. If you prefer to work in meters, use the speed of sound in meters per second, roughly 341mps (depending on temperature). 341/40=8.525x2=17M

If you just barely have enough sub to cover your needs, you'll get better results clustering them together, even on one side. The +3dB increase in sensitivity that mutual coupling gives you is equal to the effect of running twice the power. It will provide better coverage over the entire venue and the people on the other side will have plenty and won't know what they're missing.

Ultimately, it's just best practices guidelines. Play around with it and see for yourself what works and what doesn't. Tons and tons of sound professionals don't know or choose to ignore the science and physics of sound and still make money with mediocre sound. So, it's not like you'll burn in hell if you don't follow the advice. But it's there if you want the best results you can get.

If you can transport the 36" wide version... that deal is a beast on the sensitivity chart, very loud! In all reality, the T39 will outperform the Mackie too and may suite you well and make transport easier.

Oh! BTW... if you haven't bought plans yet, you may consider getting the whole CD. Cheap, good reading, and you'll likely end up making a few other designs too once you experience the goodness.

Hi and welcome

Mattsoniclab wrote: ↑Tue Jun 15, 2021 7:11 pm I can see that grouping them together in the middle might be the best way to go, although that's not always practical - nor is putting them together on one side, as a bunch of people on the other side of the stage will just be getting the tops!

^This is a very common misconception.
Frequencies reproduced by subs are omnidirectional, so it matters not one iota where they are placed from that point of view.

Another misconception is to set up based on aesthetics rather than science.
Tops/mains placed on top of subs is also more often than not the wrong way to setup based on science, because it tends to allow one to ignore adequate sub separation, the distance required already having been explained earlier by Seth.

Not separating subs adequately leads to frequency cancellation in the lower part of the subs output region.

Is the T48 the right cab? Well, it's more than fine for live music, most rock, and top 40 recorded.
But you mentioned DnB.

Pick out your most bass heavy songs, load them into Audacity, and use the "content" function to work out if T48's really are going to be ok.
At least you then know, rather than guessing.
If the 10% of songs you want to play has significant sub 35Hz content (which you can cover with 4 cabs) then the only cab that does under 30Hz with total authority is the T60.

You also need to factor into your budget DSP. The driverack series from DBX are nowadays the best value for money in that regard, since it does all you need (and more) in a 1 RU box. This is not desirable, it's mandatory.
Horn subs don't complain like direct radiators (ie, display distortion), they simply stop working because they blow the drivers if you exceed their limits. That, in itself, is embarrassing, and hurts your "business"...

Ask as many questions as you need! Nothing worse than going to the time and effort to build, only to find out you made the wrong choice...

The +3dB increase in sensitivity that mutual coupling gives you is equal to the effect of running twice the power.

It's +6dB, equivalent to quadrupling power.

Bill Fitzmaurice wrote: ↑Wed Jun 16, 2021 6:45 am

The +3dB increase in sensitivity that mutual coupling gives you is equal to the effect of running twice the power.

It's +6dB, equivalent to quadrupling power.

Clarification on this for the casual reader...

Adding a second subwoofer(or doubling a stack of subs), yet placing it more than ½ wavelength of a produced frequency from the initial subwoofer will not mutually couple and the system output will typically see a 3dB average increase. However, if the second sub (or stack of subs) is moved closer to the initial sub/stack (between ¼-½ wavelength), the cabs output couple and act as one single cab and the output increases another 3dB for free, just for having them close enough to couple... ultimately a 6dB gain over not having the second sub (stack) to begin with.

There are plenty of reference sources available. A quick googling brings up a decent article on the QSC website; What does Subwoofers Mutual Coupling Mean

I use T48s outside without reinforcement frequently. Clustering is important. General rule of thumb is 2x the number of tops. Simply stated, I’ve never wished for something different doing live music and most recorded tracks. These subs absolutely perform.

Seth wrote: ↑Mon Jun 21, 2021 6:00 pm Adding a second subwoofer(or doubling a stack of subs), yet placing it more than ½ wavelength of a produced frequency from the initial subwoofer will not mutually couple and the system output will typically see a 3dB average increase. However, if the second sub (or stack of subs) is moved closer to the initial sub/stack (between ¼-½ wavelength), the cabs output couple and act as one single cab and the output increases another 3dB for free, just for having them close enough to couple... ultimately a 6dB gain over not having the second sub (stack) to begin with.

I didn't notice this when originally posted, but now that the thread has been resurrected...the difference between when sources are mutually coupled or not isn't 3dB. When mutually coupled you get a 6dB sensitivity increase across the full bandwidth. When not mutually coupled you still get 6dB at most frequencies, but not at all frequencies, depending on the relative positions of the sources and the listener. There can even be cancellation notches at some frequencies. Preventing that is why you should either place subs less than 1/2 wavelength or more than 2 wavelengths apart.

Bill Fitzmaurice wrote: ↑Tue Jun 07, 2022 6:37 am

Seth wrote: ↑Mon Jun 21, 2021 6:00 pm Adding a second subwoofer(or doubling a stack of subs), yet placing it more than ½ wavelength of a produced frequency from the initial subwoofer will not mutually couple and the system output will typically see a 3dB average increase. However, if the second sub (or stack of subs) is moved closer to the initial sub/stack (between ¼-½ wavelength), the cabs output couple and act as one single cab and the output increases another 3dB for free, just for having them close enough to couple... ultimately a 6dB gain over not having the second sub (stack) to begin with.

I didn't notice this when originally posted, but now that the thread has been resurrected...the difference between when sources are mutually coupled or not isn't 3dB. When mutually coupled you get a 6dB sensitivity increase across the full bandwidth. When not mutually coupled you still get 6dB at most frequencies, but not at all frequencies, depending on the relative positions of the sources and the listener. There can even be cancellation notches at some frequencies. Preventing that is why you should either place subs less than 1/2 wavelength or more than 2 wavelengths apart.

Is the information in the link I posted incorrect or incomplete? Have I misinterpreted it, maybe?
What does Subwoofers Mutual Coupling Mean

As far as I am concerned, the horn loaded designs being promoted and discussed on this forum are superior to all other subwoofer design options and configurations. The reality is that superiority is situationally subjective. The cost savings with the trade off requiring time, skills and resources. If you do not have wood working tools, shop space and some fabrication skills, as well as some time on you hands to build the speakers than these loud speakers may not be the best path. If you do have a DIY tendency and funds are more limited than time you should be able to carefully acquire enough tooling and the material to build the gear for less than commercially available equivalents. Efficiency, the compromise between size of equipment, power/energy consumption, output spl and fidelity, with these horn loaded designs at the cost of larger more complex cabinetry you get a lot of output on very little power consumption. I personally resent the likes of Bose, who’s visual appeal trumps the acoustic accuracy target. I personally could care less what it looks like as long as it sounds right, then once sounding right the visual aspects get addressed. I also really value the “I built it myself” factor especially after a successful show, it’s that little decorative icing on the cake that really completes the package. If your room and pack space is highly limited than these large horns may not be the best option.