I'd like to add a pair of subwoofers to the system described here. The bass, except for the bottom octave, is extremely satisfying as is. Acoustic bass is more convincing than I've heard from most conventional boxed speakers. But the 20-40 Hz requires a lot of cone excursion with open baffles, so I'm looking for suggestions for subwoofer drivers.
While the current system is optimized for music (my priority), I'd like to add to the home theater fun and reduce the risk of bottoming out the open baffle woofers when the T-rex footsteps arrive. It's only happened once or twice, but it makes me cringe. So I'd like to back off on the very-low frequency equalization on the open baffle woofer array, and make up (and then some) the bottom octave output with a pair of sealed box subwoofers.
I've already pushed the tolerance of my co-listener with the twin tower speakers, and more recently, the addition of sound absorbing panels behind the speakers. So I need subwoofers that are not visually intrusive: small but capable. I have zero interest in bragging about an extra 2 dB at 16 Hz, and I never listen at really high SPLs. But the speakers are at the end of a large great-room (about 20' x 60') so there's a lot of room to fill with sound.
I have two channels of ICEpower to drive the woofers (500 watts/channel into 8 ohms, 1 kW into 4 ohms). I've been eyeing the Sound Integrity SQL 12" and 15" woofers so far. They're currently offered at slightly reduced prices. They're described as working in 1 ft^3 and 2 ft^3 sealed boxes, respectively, although modeling shows them to start rolling off at pretty high frequencies in those boxes. I'm assuming they're intended to be used with lots of bass boost to get good response down to 20 Hz.
I'd like to avoid going any higher in price, if possible, and to keep the box volume low I'm aiming for sealed enclosures. Are there other drivers I should be considering? I haven't spent a lot of time learning what's out there in the subwoofer driver market.
Thanks in advance for any suggestions.
Few
While the current system is optimized for music (my priority), I'd like to add to the home theater fun and reduce the risk of bottoming out the open baffle woofers when the T-rex footsteps arrive. It's only happened once or twice, but it makes me cringe. So I'd like to back off on the very-low frequency equalization on the open baffle woofer array, and make up (and then some) the bottom octave output with a pair of sealed box subwoofers.
I've already pushed the tolerance of my co-listener with the twin tower speakers, and more recently, the addition of sound absorbing panels behind the speakers. So I need subwoofers that are not visually intrusive: small but capable. I have zero interest in bragging about an extra 2 dB at 16 Hz, and I never listen at really high SPLs. But the speakers are at the end of a large great-room (about 20' x 60') so there's a lot of room to fill with sound.
I have two channels of ICEpower to drive the woofers (500 watts/channel into 8 ohms, 1 kW into 4 ohms). I've been eyeing the Sound Integrity SQL 12" and 15" woofers so far. They're currently offered at slightly reduced prices. They're described as working in 1 ft^3 and 2 ft^3 sealed boxes, respectively, although modeling shows them to start rolling off at pretty high frequencies in those boxes. I'm assuming they're intended to be used with lots of bass boost to get good response down to 20 Hz.
I'd like to avoid going any higher in price, if possible, and to keep the box volume low I'm aiming for sealed enclosures. Are there other drivers I should be considering? I haven't spent a lot of time learning what's out there in the subwoofer driver market.
Thanks in advance for any suggestions.
Few
Parts express reference HO woofers do well small sealed and boosted.
Grimm audio uses the peerless divers in small boosted (servo) boxes also.
I'd do a small dual opposed push push with 8 Ohm 10's. Parts express reference HO. Will take all of your power amp and lots of excursion. Nice thick aluminum cones to handle the internal pressure.
Grimm audio uses the peerless divers in small boosted (servo) boxes also.
I'd do a small dual opposed push push with 8 Ohm 10's. Parts express reference HO. Will take all of your power amp and lots of excursion. Nice thick aluminum cones to handle the internal pressure.
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By the way, funny you should mention Grimm Audio. I've been bingeing on Grimm for the last three days (videos and white papers). What an interesting collection of people working toward a laudable goal! I noticed they mentioned Dayton Audio drivers as one option for their servo sub, but the white paper says they went with SEAS. Maybe they changed drivers after writing things up?
A pair of the Dayton 10" drivers is about the same cost as one of the 15" SI SQL woofers. Quite a difference in x_max, though (28.4 mm vs. 13.25 mm). I do like the dual-opposed configuration. As an alternative, I considered mounting a single woofer with its magnet pressed against my concrete floor as a mechanical ground. That would require risking suspension sag, though. And I've have to be sure the magnet didn't rattle against the floor.
A pair of the Dayton 10" drivers is about the same cost as one of the 15" SI SQL woofers. Quite a difference in x_max, though (28.4 mm vs. 13.25 mm). I do like the dual-opposed configuration. As an alternative, I considered mounting a single woofer with its magnet pressed against my concrete floor as a mechanical ground. That would require risking suspension sag, though. And I've have to be sure the magnet didn't rattle against the floor.
I'd try for some smaller push pulls smaller drivers.
They "vanish" better.
But you lose sensitivity and usually higher FS (thusly higher sealed F3's) with smaller drivers.
Otherwise, if you can tolerate 4ft3 (F3 around 32hz), I'd do a 14mm xmax rss390hf for cost ($200) vs size (of a .707 qtc) vs sealed output (xmax).
With the power losses in a subwoofer, 200w is probably not 3db louder than 100w, and at 400w, you are probably only 3db louder than what you got at 100w. So careful thinking you can just put hundreds of watts into a lower sensitivity driver and get more output, there is a balance. I only figure 100w per driver. 4 drivers are way less harmonically distorted than 1 driver moving 4 times as far.
They "vanish" better.
But you lose sensitivity and usually higher FS (thusly higher sealed F3's) with smaller drivers.
Otherwise, if you can tolerate 4ft3 (F3 around 32hz), I'd do a 14mm xmax rss390hf for cost ($200) vs size (of a .707 qtc) vs sealed output (xmax).
With the power losses in a subwoofer, 200w is probably not 3db louder than 100w, and at 400w, you are probably only 3db louder than what you got at 100w. So careful thinking you can just put hundreds of watts into a lower sensitivity driver and get more output, there is a balance. I only figure 100w per driver. 4 drivers are way less harmonically distorted than 1 driver moving 4 times as far.
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Thanks NB,
4 ft^3 is outside the acceptable range, I'm afraid. I don't harbor delusions about the magic of kilowatts. I understand that chasing SPLs by increasing kW is not a promising trajectory. Fortunately, I'm not aiming for record-breaking SPLs. I just want to augment what I have without triggering a divorce.
My goal is high fidelity bass, with small sealed enclosures, with the understanding that I'll have to pay a price through efficiency and probably maximum SPL. Since I don't need 110 dB at 20 Hz, I"m hoping I can find a sensible compromise.
Few
4 ft^3 is outside the acceptable range, I'm afraid. I don't harbor delusions about the magic of kilowatts. I understand that chasing SPLs by increasing kW is not a promising trajectory. Fortunately, I'm not aiming for record-breaking SPLs. I just want to augment what I have without triggering a divorce.
My goal is high fidelity bass, with small sealed enclosures, with the understanding that I'll have to pay a price through efficiency and probably maximum SPL. Since I don't need 110 dB at 20 Hz, I"m hoping I can find a sensible compromise.
Few
high fidelity bass, less distortion ?
definitely push pull then.
check this review out.
KEN KREISEL DXD-12012 Dual 12" Push-Pull Subwoofer - HomeTheaterHifi.com
how are you going to integrate it ?
The subwoofer's crossover and its delay really make a mess of timing, thus quality, but that is another huge issue.
so, 2 boxes, how many ft3 each can you tolerate ?
And, are you adding eq ?
Most store bought big subwoofers are in too small boxes with a bunch of eq, and then subsonic protection below that.
If you are into circuits, I recommend LR transfer. You basically put a driver in a too small box (so it rolls off at 80hz) then you add a low pass filter with a 12db rolloff (starting at say 20hz). Overall you get pretty flat from 20-80hz in a small box, but 20hz has +24db of boost, and maybe 90db @ 20hz, but it is an option.
Anyone else know of any sealed (un boosted) F3's near 30hz ?
definitely push pull then.
check this review out.
KEN KREISEL DXD-12012 Dual 12" Push-Pull Subwoofer - HomeTheaterHifi.com
how are you going to integrate it ?
The subwoofer's crossover and its delay really make a mess of timing, thus quality, but that is another huge issue.
so, 2 boxes, how many ft3 each can you tolerate ?
And, are you adding eq ?
Most store bought big subwoofers are in too small boxes with a bunch of eq, and then subsonic protection below that.
If you are into circuits, I recommend LR transfer. You basically put a driver in a too small box (so it rolls off at 80hz) then you add a low pass filter with a 12db rolloff (starting at say 20hz). Overall you get pretty flat from 20-80hz in a small box, but 20hz has +24db of boost, and maybe 90db @ 20hz, but it is an option.
Anyone else know of any sealed (un boosted) F3's near 30hz ?
there is isobaric (think of clamshelling 2 drivers together).
2 x 8ohm coiled subs is now a 4ohm load but needs a box half as big as required as one.
Oh, and you lose 3db also...….
I think that is how they are, I don't see much about them.
2 x 8ohm coiled subs is now a 4ohm load but needs a box half as big as required as one.
Oh, and you lose 3db also...….
I think that is how they are, I don't see much about them.
this 15" makes 35Hz Qtc=0.7 in a 60L closed enclosure the weight is enormous though
https://www.parts-express.com/pedoc...ess-stw-350f188pr01-04-technical-overview.pdf
https://www.parts-express.com/pedoc...ess-stw-350f188pr01-04-technical-overview.pdf
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I use a pair of 10" Scanspeak 26W/8534G00 in 77L (2.2cuft) sealed enclosures and that has an F3 of 41Hz and an F6 (the one that matters for sealed indoor) of 31Hz. In room i have all the bass i need for bass heavy music like UK steppers dub that i like. The only disadvantage is a maximum of 95dB for one box (98dB for a pair) at that F6. But that is plenty loud in an average living room or music room i think. The driver is one of the Scanspeak (relative) cheaper drivers but sounds very good lik all of Scanspeak.
The 12" SB34NRX75-6 works in the same cabinet (but i build mine before that SB driver was availble) and goes lower and louder. An F3 of 36,4Hz and an F6 of 29.6Hz, with a maximum volume of 103dB at that F6 for one box. The driver is slightly more expensive (but not that much) and would be what i would use now. I did build it with the SB for a friend, and the sound is equal quality as the Scanspeak i have to say (they stood side by side while testing).
The 12" SB34NRX75-6 works in the same cabinet (but i build mine before that SB driver was availble) and goes lower and louder. An F3 of 36,4Hz and an F6 of 29.6Hz, with a maximum volume of 103dB at that F6 for one box. The driver is slightly more expensive (but not that much) and would be what i would use now. I did build it with the SB for a friend, and the sound is equal quality as the Scanspeak i have to say (they stood side by side while testing).
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The op wants it crossed higher, his OB's that he will use with this sub go to 150Hz, so this does not work. Pushpull subs work if you can crosso lower at 75 to max 100Hz, sealed can go a lot higher.
Very near field is the go then if you need small sealed enclosures. Right behind the couch or one either side pointing inwards at both of you. PR cabs are another alternative for low freq (sub 20hz easily), 12" with a 12" PR in 1.2-1.5cuft. Drivers need 30hz or lower FS and both driver and PR need plenty of excursion.
The Linkwitz Transform as mentioned is another way but requires a lot of power and a lot of excursion along with if your recording (bluray copy, pirated etc) isn't the same volume then things can go pear shaped quickly so being able to repair damaged equipment (is pretty easy just time consuming) should be a factor.
Either way Nearfield is the go...
The Linkwitz Transform as mentioned is another way but requires a lot of power and a lot of excursion along with if your recording (bluray copy, pirated etc) isn't the same volume then things can go pear shaped quickly so being able to repair damaged equipment (is pretty easy just time consuming) should be a factor.
Either way Nearfield is the go...
Thanks for the assistance!
I wil be using a MiniDSP for the crossover and equalization. I’m going to use the existing open baffles for as much of the range as I can because I’m very happy with them. It’s really the bottom octave that I’m focused on. I’ll likely set the crossover at 40-50 Hz. So far I’ve been using IIR filters to minimize latency issues; the speakers are used for movies as well as music.
I did consider isobaric but I’m not sure I’d shed enough enclosure size to justify it. The motors on the subwoofers are so big that by the time they’re accommodated I think I’d be close to where I started.
The Kreisel subwoofer looks great. I’m surprised the dual drivers aren’t aligned on opposite walls to cancel the forces but clearly they do what they’re supposed to. I wonder what they’re using for drivers.
Few
I wil be using a MiniDSP for the crossover and equalization. I’m going to use the existing open baffles for as much of the range as I can because I’m very happy with them. It’s really the bottom octave that I’m focused on. I’ll likely set the crossover at 40-50 Hz. So far I’ve been using IIR filters to minimize latency issues; the speakers are used for movies as well as music.
I did consider isobaric but I’m not sure I’d shed enough enclosure size to justify it. The motors on the subwoofers are so big that by the time they’re accommodated I think I’d be close to where I started.
The Kreisel subwoofer looks great. I’m surprised the dual drivers aren’t aligned on opposite walls to cancel the forces but clearly they do what they’re supposed to. I wonder what they’re using for drivers.
Few
That is why I suggested dual opposed 10's. Motor force cancels and enclosure vibration is reduced. I was thinking 12 inch cubic enclosure but you could make one end longer inset the baffle and reverse mount the driver. This would reduce driver mechanical distortion. But then you would have to seal the driver lead wires really well going back into the enclosure.
Thanks Troy. I caught your meaning. I think it’s a good idea.
Thinking out loud... I want the subwoofers near the main speakers because they’ll be less intrusive and I think it’s a reasonable spot acoustically. My current thinking is that I could build small boxes that fit under the 15” x 18” base of each open baffle woofer tower. I would want to minimize the height that I add, but if I make the box barely tall enough to accommodate 10” or 12” drivers, that would probably work.
If I use 3/4” thick (braced) side walls, and 13” height, I get about 1.8 ft^3 (without accounting for the volume displaced by the woofers). Doing the “one facing in, one facing out” trick, with the drivers along the same axis, I could point one forward and one toward the rear. Maybe I could get that to work with dual 12” Reference OH Daytons to get a bit more volume displacement at relatively little cost increase relative to the 10” woofers.
I like the distortion cancelling effect of woofers facing in and out of the box. Too bad it makes it harder to couple the magnets together to minimize vibrations transferred to the cabinet. Has anyone figured out a way of accomplishing both goals simultaneously?
I’ve had servo-woofers on my “that would be fun” list forever but I think I’ll avoid adding that to this project for now.
Again, thanks for the helpful suggestions and ideas.
Few
Thinking out loud... I want the subwoofers near the main speakers because they’ll be less intrusive and I think it’s a reasonable spot acoustically. My current thinking is that I could build small boxes that fit under the 15” x 18” base of each open baffle woofer tower. I would want to minimize the height that I add, but if I make the box barely tall enough to accommodate 10” or 12” drivers, that would probably work.
If I use 3/4” thick (braced) side walls, and 13” height, I get about 1.8 ft^3 (without accounting for the volume displaced by the woofers). Doing the “one facing in, one facing out” trick, with the drivers along the same axis, I could point one forward and one toward the rear. Maybe I could get that to work with dual 12” Reference OH Daytons to get a bit more volume displacement at relatively little cost increase relative to the 10” woofers.
I like the distortion cancelling effect of woofers facing in and out of the box. Too bad it makes it harder to couple the magnets together to minimize vibrations transferred to the cabinet. Has anyone figured out a way of accomplishing both goals simultaneously?
I’ve had servo-woofers on my “that would be fun” list forever but I think I’ll avoid adding that to this project for now.
Again, thanks for the helpful suggestions and ideas.
Few
I have always wanted to couple the divers mechanically with aluminum rod with threaded holes on the ends. Just four rods on an eight hole basket. Make the rods 1/16 to 1/4" short so the bolts pull in and pretention the baffle.. wala, rigidly coupled the drivers. Could be used for drivers mounted in either direction.
But I don't have a machine shop or metal tools so I never got around to trying it.
Instead I use dual voice coil drivers and series one coil on each woofer so the drivers are coupled electronically. When one has voltage and moves the other moves. Four 4 Ohm voice coils in series/parallel maintains a 4 ohm load but the drivers are now coupled. Add the rods and bam!
But I don't have a machine shop or metal tools so I never got around to trying it.
Instead I use dual voice coil drivers and series one coil on each woofer so the drivers are coupled electronically. When one has voltage and moves the other moves. Four 4 Ohm voice coils in series/parallel maintains a 4 ohm load but the drivers are now coupled. Add the rods and bam!
Push pull had minimal vibrations.
And you can get a push pull up to 150hz, just keep the slot no wider than 1/4 octave of 300hz.
And you can get a push pull up to 150hz, just keep the slot no wider than 1/4 octave of 300hz.
Well I have the machine shop, but I really want to couple things at the motor (magnet) rather than at the periphery of the cone. All the forces are applied where the magnet and voice coil reside, so I’d like to avoid relying on a perfectly rigid basket. The new KEF dual-opposed subwoofer driver, with concentric voice coils, and shared magnets, really takes the problem head-on. Clearly, their approach won’t be available to the proletariat buying woofers individually.
The open baffle woofers in my current system are mounted by their magnets, rather than via the usual basket mounting points, in an effort to take the basket out of the equation.
The open baffle woofers in my current system are mounted by their magnets, rather than via the usual basket mounting points, in an effort to take the basket out of the equation.
My biggest suggestion is to remember A-weighting. You need a lot more spl at 20hz than 40hz.I strongly suggest you model whatever you plan on making in bassboxpro and look at the output graphs closely.
I had similar goals and made a sump-woofer. It only weighs ~45lbs so you could hang it over the tv horizontally from the ceiling. It's a good solution to large enclosure placement, the ceiling mount uses zero floor-space.
I modified the port design to use a single 6" diameter ~26" long piece of foam core pvc pipe. I also sandwiched a skeletalized circle of particle board in-between the two basins to hold the internal end of the port at roughly the center of the enclosure. It works very well, bass guitars and pianos sound a lot more real, T-rex shakes the house.
I had similar goals and made a sump-woofer. It only weighs ~45lbs so you could hang it over the tv horizontally from the ceiling. It's a good solution to large enclosure placement, the ceiling mount uses zero floor-space.
I modified the port design to use a single 6" diameter ~26" long piece of foam core pvc pipe. I also sandwiched a skeletalized circle of particle board in-between the two basins to hold the internal end of the port at roughly the center of the enclosure. It works very well, bass guitars and pianos sound a lot more real, T-rex shakes the house.
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