Hey guys, I've got a need for some LF extension and some odd issues to try and overcome. I don't really know where to start and so I'm coming to you for help.
I need to build two enclosures for a very large room. Seats about 1800 with 80ft ceilings. I've got two floor pockets I can fill with enclosures. The openings are just under 20"x59" and they open up in length past the mouth. Overall box dimensions would need to be at or inside of 72"L x 21"H x 19" D.
I don't need amazing performance or output. It's a church and we rarely touch the 100db mark for Sunday services (91-97db at the console mid room.) But we run some events for younger ages and I would love to have a little extra headroom. FOH HF cabs are EAW KF300's. A dozen of them. They start to get flappy when pushed hard until the HPF hits about the 120hz mark. Cab dimensions will obviously dictate how low they'll play, but I can't imagine needing much extension past 40hz. I don't have any preexisting drivers to load them with, and my amplifier choices are limited atm, but I'll probably pick up some Nuke's and whatever drivers, if any, that you recommend.
I'll check this thread as often as I can. Thank you for your help.
-Nate
I need to build two enclosures for a very large room. Seats about 1800 with 80ft ceilings. I've got two floor pockets I can fill with enclosures. The openings are just under 20"x59" and they open up in length past the mouth. Overall box dimensions would need to be at or inside of 72"L x 21"H x 19" D.
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An externally hosted image should be here but it was not working when we last tested it.
I don't need amazing performance or output. It's a church and we rarely touch the 100db mark for Sunday services (91-97db at the console mid room.) But we run some events for younger ages and I would love to have a little extra headroom. FOH HF cabs are EAW KF300's. A dozen of them. They start to get flappy when pushed hard until the HPF hits about the 120hz mark. Cab dimensions will obviously dictate how low they'll play, but I can't imagine needing much extension past 40hz. I don't have any preexisting drivers to load them with, and my amplifier choices are limited atm, but I'll probably pick up some Nuke's and whatever drivers, if any, that you recommend.
I'll check this thread as often as I can. Thank you for your help.
-Nate
Always, if in a hall or room, use one enclosure. This will ensure thetre is no phase shift as one moves around the hall/room causing no bass in pockets. The human ear does not detect where sub bass comes from and there is no need for more cabinets. If you have two cabinets supplying sub bass, put them together to avoid phase shift issues.
Put them together as in physically touching each other/coupled? Or do you mean put them near to each other. They'll be within two of feet of each other in the floor pockets.
Regardless of SPL, the better sub coupling you have, the less you need to drive your amps. As long as you're within 1/4 wavelength center-to-center of the highest frequency produced by the subs, you're good to go. For a crossover point of 120Hz, that's around 28.25" C-to-C. You might try underlapping the crossover; for instance, 100Hz subs & 120Hz tops.
Driver & DIY design suggestions can only follow budget limitations...?
Driver & DIY design suggestions can only follow budget limitations...?
~16.5 cubic feet of space per box, which might mean about 14-15 cubic feet when accounting for enclosures. Not sure what fits, but output/$ seems to be the 8 12"ers for $100 (edit to add: www.zalytron.com). Yes, they have a xmax of around 5mm, but 4 of those sealed in each space would get you a Qtc ~0.88 and a mid 30's f3. Not amazing, and there are single cabinets that will outpace what this would do, but with some simple eq'ing (~25hz 2nd order high pass) and pretty modest power, it should throw a lot of volume around for $600ish. ($150 speakers, $150 wood/etc +$300 amp)
Sealed boxes are easy, too, which is why this came to mind. The 16 hz organ thread might also be of use to read, even though you're not looking for anything near that kind of output.
Sealed boxes are easy, too, which is why this came to mind. The 16 hz organ thread might also be of use to read, even though you're not looking for anything near that kind of output.
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I'm absolutely certain that eight low SPL 12" car/home audio woofers in sealed enclosures aren't going to come anywhere close to keeping up with a dozen KF300 tops. Especially in a sealed box, you'll likely fry them before you even know they're working. You need as many 15" or 18" pro audio drivers in vented boxes as can fit, or go horn-loaded with competent DIY designs featuring pro audio 12" or 15" drivers. Look for drivers with an Xmax no less than 8mm; 10mm or longer is better. Horns take more space & don't go quite as low as bass reflex, but it's hard to argue with an SPL of 105dB (or more).
Don't be in a hurry to buy into our suggestions until you do your homework. Buy once, cry once....
Don't be in a hurry to buy into our suggestions until you do your homework. Buy once, cry once....
I completely agree as far as global output, but am I reading too much into the OP? It seems he's looking for something relatively inexpensive and not needing absolutely gargantuan output (nor does it sound like those dozen KF300's are being pushed at all), so that was the premise of my suggestion.
If he needs that ~130 dB/1m output at 40hz, then, yes, he'd better bring a healthy budget and be looking at a few 15-18"ers. (Looking, a few B&C 18's do well in 7 cubic foot boxes tuned to 35hz). Your point about budget does drive everything.
If he needs that ~130 dB/1m output at 40hz, then, yes, he'd better bring a healthy budget and be looking at a few 15-18"ers. (Looking, a few B&C 18's do well in 7 cubic foot boxes tuned to 35hz). Your point about budget does drive everything.
Four Dayton 295-120 12's, 100dB/2.83V/1M, 8Ω, will handle over 1KW (130dB) with no x-max issues.
W24" x H48" x D24", but may be stretched and squeezed to fit your space. F3=40hz, with Q=2 filter, Fb=27hz, F3=27hz.
(cat is optional)
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I'll try and speak with the powers that be to determine what my budget is. I meant to add, but forgot to, we own 4 QSC KSubs. They're each a pair of 12's at 1000w rms. They're floaters for various events and can't be installed permanently. Plus they don't fit in the holes. QSC advertises 130db max (at a meter, I guess). We have tried them in the room in the past and they did decent. For a Sunday service, they didn't do bad, but I wouldn't mind a little more extension on the low side. For events that occasionally go mid-concert level, I would love to have more output. We ran an event for kids with peaks at around 105db and they did ok, but they were at their limits. I was seeing a lot of clip lights on the boxes. Specs say 48Hz-134Hz (±6dB). They're pretty small boxes meant to be transported easily, so that may have something to do with the freq limitations.
I add this to try and help establish what my needs are. Sorry for my lack of knowledge, guys. I'm not really a forum goer, and I'm certainly not a system expert. I definitely appreciate the help so far and will continue to answer as many questions as I can.
I add this to try and help establish what my needs are. Sorry for my lack of knowledge, guys. I'm not really a forum goer, and I'm certainly not a system expert. I definitely appreciate the help so far and will continue to answer as many questions as I can.
To add to that, I'm not in a hurry to throw any money away for sure. This project is near the top of my to-do list, but it isn't incredibly critical. I'll be sure to do as much research as I can before pulling the trigger on anything. Thanks again.
It's better to use multiple subs to get a more diffuse sound field. Search for 'multiple subs' to get papers/articles on the subject of 3+ subs and what it does to room effects. It's also much more reliable due to higher thermal handling and more than 1 breaking points.
I'm focused on the OP's placement restrictions. It seems the most bang-for-the-buck may be horns or DJK's PPSL idea. Either way, don't cut too many quality corners where drivers are concerned.
I don't know anything about the merits of a PPSL cabinet, but I have looked at a tapped horn design. However, as I'm starting from scratch with little to no knowledge, I don't know where to start when it comes to choosing a driver and designing a cab for it. Some of the long tall skinny tapped horn builds that I've seen would fit the bill for space, but most of those are for home theater and are tuned extremely low. If I understand correctly, it's horn length that affects tuning frequency the most, so maybe the groundwork has already been laid somewhere and I can just shorten an existing design. Assuming of course that a folded or tapped horn is the best choice for my setup.
To add to that: It isn't incredibly critical that this performs at new found levels of efficiency or anything. I'm not looking to set records or squeeze every last possible hair of performance out of this. I understand that there is a point of diminishing returns, and there will be an element of "close enough" to this build. I hope that you don't mistake that as laziness. I want to do the very best I can, but if the difference between $200 and $600 drivers is a few db, I'll just have to lose a few db.
To add to that: It isn't incredibly critical that this performs at new found levels of efficiency or anything. I'm not looking to set records or squeeze every last possible hair of performance out of this. I understand that there is a point of diminishing returns, and there will be an element of "close enough" to this build. I hope that you don't mistake that as laziness. I want to do the very best I can, but if the difference between $200 and $600 drivers is a few db, I'll just have to lose a few db.
Those papers all refer to acoustically small rooms, so would be largely irrelevant here in a 1800 seat venue.
If 4x KSubs struggled, then you're going to need something bigger, as that was 8x decent 12"s with plenty of power.
I'd be looking at 8x Keystone subs, 4ohm drivers, and a channel of an NU6k per box.
I'd estimate a gain of 12dB on your pile of KSubs.
Chris
I don't know that 8x keystones are going to fit in my floor pockets. Looking at the original keystone plans, one of them won't fit without massaging some dimensions.
I may be just out of my mind here with this project and it may not be possible to get what I'm looking for due to the space limitations. Eventually we intend to run something like RCF's powered arrays and fly the subs with the arrays, but that's about 5 years down the road and I was hoping to find a placeholder in the interim. And also maybe something that we could continue to use even with the RCF flown cabs in place, to supplement them, if needed.
I may be just out of my mind here with this project and it may not be possible to get what I'm looking for due to the space limitations. Eventually we intend to run something like RCF's powered arrays and fly the subs with the arrays, but that's about 5 years down the road and I was hoping to find a placeholder in the interim. And also maybe something that we could continue to use even with the RCF flown cabs in place, to supplement them, if needed.
I wouldn't pay $600 for a single driver, either! There's more to a good subwoofer driver than a few dB (altho an SPL at or above 95dB should be considered), such as motor strength (BL), VC size, RMS or AES power handling (ignore Peak), Xmax, etc. Personally, I look for a Qts between 0.28 & 0.36 for sub duty. Risking over-simplification, if the Vas is too large, the box will be too big.
Imports from high-profile manufacturers will be pricey, so stay local with brands like Eminence, or retail-outlet imports like Dayton, etc. Decide on a budget for your drivers & find a model which has the T/S closest to your design criteria.
I'm sure the denizens of this forum will help you with prediction programs, or you can download FREE copies of WinISD & Horn Response, then get forum input on their use.
Imports from high-profile manufacturers will be pricey, so stay local with brands like Eminence, or retail-outlet imports like Dayton, etc. Decide on a budget for your drivers & find a model which has the T/S closest to your design criteria.
I'm sure the denizens of this forum will help you with prediction programs, or you can download FREE copies of WinISD & Horn Response, then get forum input on their use.
Years ago I did a pair of double 15 PPSL for a similar sized church in the D.C. area, with only 400W per box they could bring you to your knees.
The local orchestra needed an effects sub for dinosaur stomps to accompany the Jurrasic Park piece in a 2000 seat theater. A block of four dual 15 PPSL driven with a 650W amp was knocking pieces out of the ceiling, they were thinking of putting in a net.
The local River of Life church installed the same block of four dual 15 PPSL for their Easter service, wanting it to feel like an earthquake. A 100W Rolls amplifier was used.
Note the older style 650W Adcom GFA555 in the rack (used in the 2000 seat theater). The Crest CA9 was used for EDM in this 3000 seat ballroom, it played 122dB on program material at 20', which translates back to 138dB at 1M, only 1KW on the low end!
The local orchestra needed an effects sub for dinosaur stomps to accompany the Jurrasic Park piece in a 2000 seat theater. A block of four dual 15 PPSL driven with a 650W amp was knocking pieces out of the ceiling, they were thinking of putting in a net.
The local River of Life church installed the same block of four dual 15 PPSL for their Easter service, wanting it to feel like an earthquake. A 100W Rolls amplifier was used.
Note the older style 650W Adcom GFA555 in the rack (used in the 2000 seat theater). The Crest CA9 was used for EDM in this 3000 seat ballroom, it played 122dB on program material at 20', which translates back to 138dB at 1M, only 1KW on the low end!
Four Dayton 295-120 12's, 100dB/2.83V/1M, 8Ω, will handle over 1KW (130dB) with no x-max issues.
W24" x H48" x D24", but may be stretched and squeezed to fit your space. F3=40hz, with Q=2 filter, Fb=27hz, F3=27hz.
(cat is optional)
This is funny. I have the same end table, carpet, paint, trim and piles of wire in my basement.
Overall, this Dayton 15" driver looks like it might be a good candidate for a PPSL:
Dayton Audio PA385S-8 15" Pro Subwoofer 4" VC 8 Ohm
Dayton Audio PA385S-8 15" Pro Subwoofer 4" VC 8 Ohm
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