FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Loren Jones

Sophomore
Jun 25, 2011
155
0
16
Hampton Roads VA
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

The dual Lab 12 has almost identical low frequency output in a smaller box with the same Fb as the BC18SW115-4.The BC18SW115-4, given twice the power, will get about 3 dB louder than the Lab 2x12.But it takes a bigger box to do it.The exterior dimensions of the box I used to test the BC18SW115-4 are 36 x 24 x 17 inch, 8.5 cubic feet compared to 7.76 for the 2x12. In all but the 38 Fb test, the magnet was outside the box, effectively adding about .56 of a cubic foot. That said, bigger is better (until Xmax is exceeded before Pmax) but the boxes are very close in volume.The BC18SW115-4 with the 37 Hz tuning almost exactly overlays the Lab 12, were it not for the lower upper filter on the Lab 12 , they would look more identical.Art Welter
The dual lab 12 design looks really nice especially if extended LF output in a small box matters more than absolute output at a little higher frequency. I am anticipating a sub build coming up for the church youth system (the 21" RCF cabs I built previously were so good that they got taken from the youth system I built them for and used in our main sanctuary system in place of 3 EAW dual 15's). So I am strongly considering a pair of the dual lab 12's here vs a pair of single 18" cabs. Because of cost I would opt for the tbx100 rather than the sw115 (one tbx100 costs about the same as 2 lab 12's). So from your testing of the dual lab 12 vs sw115 you say the sw115 will give 3db more output with twice the power. B&C has a recommended enclosure for the sw115 with fb of 35 hz and excursion limited output of 124.9 db and their recommended enclosure for tbx 100 gives fb of 34 hz and excursion limited output of 120.3 db. Given that, do you think it would be safe to say the tbx100 in said enclosure would be pretty similar to your dual lab12 design. Granted the box for the tbx 100 is a fair bit larger. Does the single 18" have any advantage I am missing or would the dual lab 12 be a better choice since the box is smaller and output is very similar? Power will likely be an MA2400 so that would be one dual lab 12 per channel or both 18's on the bridged amp so the dual lab 12 would likely see slightly less power but not significantly so.Thanks for any thoughts,Loren Jones
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

So from your testing of the dual lab 12 vs sw115 you say the sw115 will give 3db more output with twice the power. B&C has a recommended enclosure for the sw115 with fb of 35 hz and excursion limited output of 124.9 db and their recommended enclosure for tbx 100 gives fb of 34 hz and excursion limited output of 120.3 db. Given that, do you think it would be safe to say the tbx100 in said enclosure would be pretty similar to your dual lab12 design. Granted the box for the tbx 100 is a fair bit larger. Does the single 18" have any advantage I am missing or would the dual lab 12 be a better choice since the box is smaller and output is very similar?
Loren,

Just looked here and found your questions unanswered for two months..
Given enough power, the B&C18SW115 definitely will outperform a pair of Lab 12" but will require a much larger BR cabinet.
The ceramic magnet B&C18TBW100 is very nearly the equal to the B&C18SW115 but is much lower cost now that Neo pricing has skyrocketed.

The B&C TBX100 series at 11mm has slightly less Xmax than the Lab 12, there is no replacement for displacement.
That said, a pair of B&C12TBX100 can outperform the Lab 12 in all but the VLF range in a smaller cabinet according to simulations.

Art Welter
 

Loren Jones

Sophomore
Jun 25, 2011
155
0
16
Hampton Roads VA
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Loren,

Just looked here and found your questions unanswered for two months..
Given enough power, the B&C18SW115 definitely will outperform a pair of Lab 12" but will require a much larger BR cabinet.
The ceramic magnet B&C18TBW100 is very nearly the equal to the B&C18SW115 but is much lower cost now that Neo pricing has skyrocketed.

The B&C TBX100 series at 11mm has slightly less Xmax than the Lab 12, there is no replacement for displacement.
That said, a pair of B&C12TBX100 can outperform the Lab 12 in all but the VLF range in a smaller cabinet according to simulations.

Art Welter

Art,

Thanks for the reply. I figured you just hadn't noticed and would get to it when you could. I have recently seen 18SW115 in action and will say it is an impressively capable driver. TBW100 certainly looks like a tremendous value if the extra weight and last couple db of output aren't needed.

Loren
 
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Does anybody have any thoughts on building this design with the Lab 12C, wired in series for 8 ohms? I was thinking of using an XTI6002 for power.
 

Ben Gingerich

Sophomore
Oct 19, 2012
188
0
16
Warner Robins Ga
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

The other thought i had was wiring the current version in series and then connecting the 2nd cab to give you a total of 3 ohms.

The only problem i see is no amps are rated at 3ohms, but to be safe i would say only use a 2ohm rated amp.
 
Last edited:
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

The other thought i had was wiring the current version in series and then connecting the 2nd cab to give you a total of 3 ohms.

The only problem i see is no amps are rated at 3ohms, but to be safe i would say only use a 2ohm rated amp.

Any amp rated for 2 ohms should be fine, I don't think I would be adventurous enough to bridge any amps at 3 ohms though.
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Spenser,

I think the 12C is more oriented for car audio, where a single speaker with low impedance is more useful.
The 500 watt Lab 12C is only 3.11 ohms (compared to 400 watt 4.29 ohms for the Lab 12) , so at the impedance minima a pair in series will be about 6.2 ohms.
If you want a lot of power (between 1600-2000) series the pair and run the amp bridged mono.
At 1.55 ohms for a pair in parallel, even some 2 ohm rated amps will cough with that load.

The Lab motor is not very effective at getting rid of heat, my guess is very little (if anything) would be gained using the extra power the 12C can take, I'd just use Lab12 and parallel a pair of them on any amp that puts out more at 2 ohms than 4.

Art
 
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Spenser,

I think the 12C is more oriented for car audio, where a single speaker with low impedance is more useful.
The 500 watt Lab 12C is only 3.11 ohms (compared to 400 watt 4.29 ohms for the Lab 12) , so at the impedance minima a pair in series will be about 6.2 ohms.
If you want a lot of power (between 1600-2000) series the pair and run the amp bridged mono.
At 1.55 ohms for a pair in parallel, even some 2 ohm rated amps will cough with that load.

The Lab motor is not very effective at getting rid of heat, my guess is very little (if anything) would be gained using the extra power the 12C can take, I'd just use Lab12 and parallel a pair of them on any amp that puts out more at 2 ohms than 4.

Art

Thanks for the insight Art. My reason for wanting to wire a pair of Lab 12C in series was so that I could eventually run 2 per channel on a XTi6000 (or a potential IT4000 that I may have a line on), you think it would be smarter to wire a pair of Lab 12 in parallel and then run 1 per channel on an amp that puts out a bit less power then?
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Thanks for the insight Art. My reason for wanting to wire a pair of Lab 12C in series was so that I could eventually run 2 per channel on a XTi6000 (or a potential IT4000 that I may have a line on), you think it would be smarter to wire a pair of Lab 12 in parallel and then run 1 per channel on an amp that puts out a bit less power then?
My experience is that depending on the amp, a rating between 1000 to 2000 watts is about right for a pair of Lab 12 in the ported cabinet.
My experience has been that some switching power supply amps need to be rated at double or more the power of "heavy metal" amps to be equivalent in low frequency output.
I have no A/B experience with the XTi6000 compared to any amps I know, so can't be of much specific help other than I'd want to see a rating of no less than 1000 watts per Lab 12 cone on a switching PSU amp.
 
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

My experience is that depending on the amp, a rating between 1000 to 2000 watts is about right for a pair of Lab 12 in the ported cabinet.
My experience has been that some switching power supply amps need to be rated at double or more the power of "heavy metal" amps to be equivalent in low frequency output.
I have no A/B experience with the XTi6000 compared to any amps I know, so can't be of much specific help other than I'd want to see a rating of no less than 1000 watts per Lab 12 cone on a switching PSU amp.

Thanks Art. Probably going to order up a pair of Lab 12 early next week, I'll try to post some pics.
 
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Project got delayed for the holidays, just ordered some parts today. I've been studying all the attachments in this thread and think I have a good grasp of the build process. Art, you wouldn't happen to have any pictures of the Grill Angle Piece meeting with the baffle. Looks like there is going to be some carefully cut angles involved to get those pieces to mate properly.
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Project got delayed for the holidays, just ordered some parts today. I've been studying all the attachments in this thread and think I have a good grasp of the build process. Art, you wouldn't happen to have any pictures of the Grill Angle Piece meeting with the baffle. Looks like there is going to be some carefully cut angles involved to get those pieces to mate properly.
The grill angle piece is just a 45" angle mitered short enough to not interfere with the grill.
 

Attachments

  • Lab 2x12 Baffle.png
    Lab 2x12 Baffle.png
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  • Four 2x12.png
    Four 2x12.png
    167.5 KB · Views: 35
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Thanks Art. So from the look of the picture, the Grill Angle Piece doesn't come into contact with the Baffle, it merely provides at attachment point for the Grill Piece?

Looking forward to finally making some dust.
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Thanks Art. So from the look of the picture, the Grill Angle Piece doesn't come into contact with the Baffle, it merely provides at attachment point for the Grill Piece?

Looking forward to finally making some dust.
The grill angle piece is glued to the baffle, it directs the port output around the grill.
The grill frame is a 3/4" x 3/4" rectangle which is screwed to the baffle.
 
Last edited:
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

So either we are misunderstanding each other, or I am picturing the port completely wrong in my head.

The piece in questions I have highlighted:
Lab 2x12 Baffle.png

From the look of the picture, that piece does not contact the baffle at all. Is that correct?
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

That 45 degree angle part goes below the grill. The parts simply keep the cross section of the port the same as it goes around the grill without an abrupt change which could cause some turbulence.
 
Sep 12, 2012
647
5
18
SW Ontario
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

Lots of delays getting this project going, finding good lumber in my area is a real pain. Finally started making sawdust earlier this week, build is going pretty quick considering I'm just working on it for about 2 hours a night after work. My last build was a BFM sub (took one of the forum guys up on a "build it before you bash it" challenge), the BFM which took about 25 hours to build was a nightmare of mitre joints, I'm pretty sure I'll be wrapping this one up in 10 hours or so. I used PL for this build because I had some left over from the BFM build, next time I think I'll go with regular wood glue and caulk the seams with PL once the box is together.

Finish is likely going to be flat black enamel paint, simple and easy to touch up.

Lab 12's are currently breaking in with a 20Hz test tone at low volume.

I thought I had the perfect placement for my handles sorted out, until I put the baffle in place and realized that one handle is going to protrude into the area of the upper port. Is this going to be a problem? Would it be worth backing the handles with 1/2" ply instead of 3/4" to minimize it's effects on port area?
 

Art Welter

Senior
Jan 11, 2011
832
19
18
Florida
Re: FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

I thought I had the perfect placement for my handles sorted out, until I put the baffle in place and realized that one handle is going to protrude into the area of the upper port. Is this going to be a problem? Would it be worth backing the handles with 1/2" ply instead of 3/4" to minimize it's effects on port area?
Reduction of port area will slightly lower the tuning and increase velocity.
How much of either will be a problem depends of how much reduction in area you plan to do.
Your description of the problem is hard for me to give any answer, post a picture and I'll give an opinion.