Again with a design that tries to fit too much deep LF into too little space, love to have everyone have a quick look to make sure I'm not missing something obvious before I pull the trigger on the build as it's been a very. long. day.
The space is primarily a lecture hall, but the client wants the capability to do minor musical performances and possibly decent quality cinema in the rig...without going too deep on budget. He is also pretty solid on wanting the subs to live under the stage, which limits us to 4 spaces that are maximum dimensions of 16"w x 12.75"h x up to 72" deep. The rectangular room dimensions are 42' long, 25' wide, with 11' ceiling that is flat. Seating starts at 3' out from the front of a 6' deep stage. The back 4 rows of desk/seats will be on progressive 6" risers. Room has acoustic ceiling treatment and carpet. Walls are untreated drywall over 'soundboard'.
Mid/high will be a single Yorkville U15 flown L&R driven by Peavey IPR2 5000DSP, Subs will be driven by IPR2 3000DSP.
I ended up recommending 4 Lab 12 in ported boxes. Here is some hornresp, a crappy cad, and a rather nice cutlist that gets it all out of 3 sheets of 3/4" ply.
Please share thoughts & if improvements come quickly enough I may be able to squeak them into the quote...and if I've missed something obvious in my haste I'll HAVE to squeak it into the quote 😉
Thanks all
The space is primarily a lecture hall, but the client wants the capability to do minor musical performances and possibly decent quality cinema in the rig...without going too deep on budget. He is also pretty solid on wanting the subs to live under the stage, which limits us to 4 spaces that are maximum dimensions of 16"w x 12.75"h x up to 72" deep. The rectangular room dimensions are 42' long, 25' wide, with 11' ceiling that is flat. Seating starts at 3' out from the front of a 6' deep stage. The back 4 rows of desk/seats will be on progressive 6" risers. Room has acoustic ceiling treatment and carpet. Walls are untreated drywall over 'soundboard'.
Mid/high will be a single Yorkville U15 flown L&R driven by Peavey IPR2 5000DSP, Subs will be driven by IPR2 3000DSP.
I ended up recommending 4 Lab 12 in ported boxes. Here is some hornresp, a crappy cad, and a rather nice cutlist that gets it all out of 3 sheets of 3/4" ply.
Please share thoughts & if improvements come quickly enough I may be able to squeak them into the quote...and if I've missed something obvious in my haste I'll HAVE to squeak it into the quote 😉
Thanks all
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You might want to look at 6th order band pass to squeeze the max SPL outbof a small volume with the lab12's. I had a design for a pretty compact 2.08 cu. ft. 40Hz box. I could probably stretch it to 20Hz at the expense of max SPL. But given that you have 4, it may be fine. Also another option since the length is long, maybe a MLTL?
Here is work on 6th order band pass:
http://www.diyaudio.com/forums/subwoofers/259509-new-sub-design-constricted-transflex-simple-build-series-tuned-6th-order-80.html#post4178367
Here is work on 6th order band pass:
http://www.diyaudio.com/forums/subwoofers/259509-new-sub-design-constricted-transflex-simple-build-series-tuned-6th-order-80.html#post4178367
I'd drop the 20Hz requirement, go to 30, and make it a TH.
You'll gain a huge pile of SPL - you're simulating for 123dB peaks at 1m. Factor in the dynamic range of a movie, plus large listening distances and you could be left wanting.
Chris
You'll gain a huge pile of SPL - you're simulating for 123dB peaks at 1m. Factor in the dynamic range of a movie, plus large listening distances and you could be left wanting.
Chris
The LAB 12 is perfect for a sealed Linkwitz Transform which will give you sub 20Hz and a small box.
Thanks guys, I looked at a few more options today. The customer insisted that getting to 120dB at source would be plenty for his vision of the room as an initial build & anything above that was a bonus, but he's also convinced that he wants it to get to 20Hz if possible, so at least I'm meeting his official spec already. He's more worried about initial schedule & costs to bring it to the table...then augment the system down the road if it seems that it needs it.
A TH was my first thought, but I was unable to come up with one that both fit and didn't look like moldy butt in response. He rejected the idea of a slim corner mounted cab, which would have made it just easy to accomplish.
Bjorno's TL idea was nice, but when I ran the models it looked to me like it was basically interchangeable with what I had so far...A touch more forgiving in the stretch around 30Hz where everything I try with this driver runs out of steam, but not dramatically so. Your posts always strike me as cryptic, but when I get the time to sit down & figure out what you're showing me I always learn useful things (thank you for that), so I'll be looking at that more later on to see if I missed something in my haste.
I've never modeled a 6th order box in hornresp, mucked with it for a few minutes as well but basically I ran out of time at that point & had to submit a plan so the carpenters at the build site could move forward assured that they left enough space...so I guess I'll run with this as an initial quote.
A TH was my first thought, but I was unable to come up with one that both fit and didn't look like moldy butt in response. He rejected the idea of a slim corner mounted cab, which would have made it just easy to accomplish.
Bjorno's TL idea was nice, but when I ran the models it looked to me like it was basically interchangeable with what I had so far...A touch more forgiving in the stretch around 30Hz where everything I try with this driver runs out of steam, but not dramatically so. Your posts always strike me as cryptic, but when I get the time to sit down & figure out what you're showing me I always learn useful things (thank you for that), so I'll be looking at that more later on to see if I missed something in my haste.
I've never modeled a 6th order box in hornresp, mucked with it for a few minutes as well but basically I ran out of time at that point & had to submit a plan so the carpenters at the build site could move forward assured that they left enough space...so I guess I'll run with this as an initial quote.
just a question... why did you not increase rear chamber size? you had more depth to play with.... a larger rear chamber and a shorter port would have increased output below 30hz (excursion maxima at 30ish hz would have restricted it to the same output)
with a 12 db/octave BW filter at 22hz, you would still have the same power handling of 35v in that your current box has.
with a 12 db/octave BW filter at 22hz, you would still have the same power handling of 35v in that your current box has.
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Well...my thinking was I'd still be limited in power handling and output volume at that 30Hz point, so there's my flat response output limit, didn't really need more below that as I'd met the output at 20Hz that was asked for (actually his literal request was 25 Hz or lower so I took 22 Hz as my goal), & it would take more wood, more bracing & more labor to go bigger. Anything larger would at least have increased my costs by another sheet of plywood & baltic 3/4 ain't cheap here. If there's an aspect I missed in favor of a bigger box I'd love to have it pointed out...'cuz vented boxes really ain't my normal thang 😉
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fwiw the SVS PC subs were designed for low freq extension in a limited space. why couldnt someone fit a pair of lab12s in sonotube tuned to about 22-24hz with a Behringer 2ch pro amp?
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