This is a new project for my friend Mark who has an enormous "great room"
30x52' with vaulted peak ceiling >20' high. The goal is not to fill the entire space with sound but the LR portion, which is about a quarter of the total floor space. Mark seeks a game-ending system, with some financial limits. He also happens to be a master metals fabricator with a lot of skills & tools, which will be brought to play.
I post this as a reality-check / peer-review of my plans.
This pic shows a fraction of the big room.
Initially, Mark wanted scaled-up versions of my LX521 clones with dual 15" SBA Nero-15SW800 in a W-frame force cancellation setup. But after examining the room again, I persuaded him that OB might be too expensive & difficult to achieve 20Hz bass at >100 dB even in just his LR space. I've heard his EV Sentry II & JBL L212 speakers in the space & there's little question the sheer size of the room is a challenge. Amending the acoustics with floating absorbers/diffusers in the ceiling (and elsewhere) is not an option due to WAF. A large rug in the LR is in the works; currently the entire space is reflective.
The current plan is a pair of 12" woofers firing sideways in opposition to each other in a sealed enclosure, topped by an OB lower mid, mid & tweeter. This would be an active system with miniDSP Flex 8 & a mix of amplifiers for the various bands, a turntable, and a Wiim Ultimate streamer/preamp.
The physical design will draw from the iconic Acoustic Research AR9 (1978-82), the modified sealed-bass LX521 I recently made for my son, and the Linkwitz Orion. Mark likes the look of my Orions, which also garner better WA. I believe I can replicate that with side-firing 12" woofers in a sealed box + a WG tweeter to reduce diffraction & control vertical directivity.
The drivers:
Woofer: SBA SB34SWPL76-4 Low sensitivity of 85 dB/2.83V, but 19Hz Fs, a low 79 liters Vas & 0.31 Qts allows 0.7 Q in a 40 liter (or smaller) box, with a slow roll-off easily amended by DSP. Two woofers in a box double that size could easily provide >100 dB to below 30Hz with force cancellation minimizing vibrations to the OB above. 15mm Xmax is excellent, as is the FR claimed in the spec sheet.
Lower Mid: Satori WO24TX -- Since it will be OB & needs to move a lot of air in this big space, I paid attention to Xmax as well as effective piston area. A 12" driver might work better in the lower frequencies (as it will get quite a lot of EQ boost to compensate for the dipole cancellation effects), but this Textreme driver is flat out to 2.5kHz on axis, with little beaming to ~1.5kHz. 8.75mm Xmax is pretty good for a driver like this, and it's an opportunity to find out first hand what a Textreme driver can do. If it can be made to cross well at 2kHz or lower to a WG dome, we might be able to keep it 3-way instead of the usual 4.
High Mid: The Satori MW13TX is a natural choice, given the WO24TX lower mid choice. It will not be necessary if we go 3-way.
Tweeter: My favorite dipole tweeter Aurum Cantus AST2650 will get a shallow waveguide on both sides. The waveguide has yet to be made, but I've seen enough iterations of such that it should not be a big challenge, executed in 3D printing or CNC cut directly in the baffle board.
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Tweeter, if 3-way: Satori TW29TXNWG Textreme is a natural. The reviews of the Beryllium WG guide version in both Audioxpress & Hificompass state they are good as low as 1kHz, and there's no reason to believe the Textreme version would be much different. The back tweeter would be the non-waveguide version -- Satori TW29TXN, which is shallow enough not to require cosmetic adjustments for the hole which might end up having to go through the baffle board with the deeper WG tweeter.
One feature that will likely be adopted from the Orion is the mounting of the lower-mid 9.5" driver by its magnet to the top of the bass bin. This config positions the driver on the baffle without touching it, preventing mechanical conduction of the driver's vibrations into the baffle. There's a foam gasket to prevent spurious vibration between the baffle hole and the driver rim. The force cancellation of the bass drivers should keep most of the larger vibrations out of both the box & baffle. This method of mounting the low mid driver will complete the primary anti-vibration scheme.
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EDIT: Forgot to mention that we'll consider adding one or 2 custom made subs, either like the one I just built with a Nero-15SW800 15" Pro driver, or the SB12" in the main speakers. The main speakers would be treated as subs (because they will be subs) and another 1 or 2 subs added to the sides of the listening area. A challenge is power outlets on one side only.
30x52' with vaulted peak ceiling >20' high. The goal is not to fill the entire space with sound but the LR portion, which is about a quarter of the total floor space. Mark seeks a game-ending system, with some financial limits. He also happens to be a master metals fabricator with a lot of skills & tools, which will be brought to play.
I post this as a reality-check / peer-review of my plans.
This pic shows a fraction of the big room.
Initially, Mark wanted scaled-up versions of my LX521 clones with dual 15" SBA Nero-15SW800 in a W-frame force cancellation setup. But after examining the room again, I persuaded him that OB might be too expensive & difficult to achieve 20Hz bass at >100 dB even in just his LR space. I've heard his EV Sentry II & JBL L212 speakers in the space & there's little question the sheer size of the room is a challenge. Amending the acoustics with floating absorbers/diffusers in the ceiling (and elsewhere) is not an option due to WAF. A large rug in the LR is in the works; currently the entire space is reflective.
The current plan is a pair of 12" woofers firing sideways in opposition to each other in a sealed enclosure, topped by an OB lower mid, mid & tweeter. This would be an active system with miniDSP Flex 8 & a mix of amplifiers for the various bands, a turntable, and a Wiim Ultimate streamer/preamp.
The physical design will draw from the iconic Acoustic Research AR9 (1978-82), the modified sealed-bass LX521 I recently made for my son, and the Linkwitz Orion. Mark likes the look of my Orions, which also garner better WA. I believe I can replicate that with side-firing 12" woofers in a sealed box + a WG tweeter to reduce diffraction & control vertical directivity.
The drivers:
Woofer: SBA SB34SWPL76-4 Low sensitivity of 85 dB/2.83V, but 19Hz Fs, a low 79 liters Vas & 0.31 Qts allows 0.7 Q in a 40 liter (or smaller) box, with a slow roll-off easily amended by DSP. Two woofers in a box double that size could easily provide >100 dB to below 30Hz with force cancellation minimizing vibrations to the OB above. 15mm Xmax is excellent, as is the FR claimed in the spec sheet.
Lower Mid: Satori WO24TX -- Since it will be OB & needs to move a lot of air in this big space, I paid attention to Xmax as well as effective piston area. A 12" driver might work better in the lower frequencies (as it will get quite a lot of EQ boost to compensate for the dipole cancellation effects), but this Textreme driver is flat out to 2.5kHz on axis, with little beaming to ~1.5kHz. 8.75mm Xmax is pretty good for a driver like this, and it's an opportunity to find out first hand what a Textreme driver can do. If it can be made to cross well at 2kHz or lower to a WG dome, we might be able to keep it 3-way instead of the usual 4.
High Mid: The Satori MW13TX is a natural choice, given the WO24TX lower mid choice. It will not be necessary if we go 3-way.
Tweeter: My favorite dipole tweeter Aurum Cantus AST2650 will get a shallow waveguide on both sides. The waveguide has yet to be made, but I've seen enough iterations of such that it should not be a big challenge, executed in 3D printing or CNC cut directly in the baffle board.
------------
Tweeter, if 3-way: Satori TW29TXNWG Textreme is a natural. The reviews of the Beryllium WG guide version in both Audioxpress & Hificompass state they are good as low as 1kHz, and there's no reason to believe the Textreme version would be much different. The back tweeter would be the non-waveguide version -- Satori TW29TXN, which is shallow enough not to require cosmetic adjustments for the hole which might end up having to go through the baffle board with the deeper WG tweeter.
One feature that will likely be adopted from the Orion is the mounting of the lower-mid 9.5" driver by its magnet to the top of the bass bin. This config positions the driver on the baffle without touching it, preventing mechanical conduction of the driver's vibrations into the baffle. There's a foam gasket to prevent spurious vibration between the baffle hole and the driver rim. The force cancellation of the bass drivers should keep most of the larger vibrations out of both the box & baffle. This method of mounting the low mid driver will complete the primary anti-vibration scheme.
EDIT: Forgot to mention that we'll consider adding one or 2 custom made subs, either like the one I just built with a Nero-15SW800 15" Pro driver, or the SB12" in the main speakers. The main speakers would be treated as subs (because they will be subs) and another 1 or 2 subs added to the sides of the listening area. A challenge is power outlets on one side only.
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Very interesting and completely out of my league.
You might be interested in checking out what this guy has done with active systems
Pat McGinty at:
Meadowlarksings.com
You might be interested in checking out what this guy has done with active systems
Pat McGinty at:
Meadowlarksings.com
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Thanks for the link. Some interesting builds. A pair of these might be able to do it all, but they're a bit too big & kinda ugly.
https://meadowlarksings.com/merlin.htm
Food for though.
https://meadowlarksings.com/merlin.htm
Food for though.
http://meadowlarkaudio.com Bad link!
Presume this one: https://www.meadowlarksings.com/
Info@patmcginty.com
Presume this one: https://www.meadowlarksings.com/
Info@patmcginty.com
Thanks GM,
Mikessi,
Kinda funny you’re comment, but I have to agree, at least somewhat. They are a bit plain and in that sense I suppose not the most attractive. They are meticulously constructed and the sound quality is exemplary imho. The designer is very open to working directly with those interested which I’ve not found to be very common. Seemingly not just to sell products, at least that’s been my experience. Ymmv of course.
Mikessi,
Kinda funny you’re comment, but I have to agree, at least somewhat. They are a bit plain and in that sense I suppose not the most attractive. They are meticulously constructed and the sound quality is exemplary imho. The designer is very open to working directly with those interested which I’ve not found to be very common. Seemingly not just to sell products, at least that’s been my experience. Ymmv of course.
On the second hand market,
Couldn’t really afford much in their line. So much from many manufacturers is so expensive. Always looking for high value, which is very subjective I know. I will be following along. That’s a huge space to conquer
Best
Couldn’t really afford much in their line. So much from many manufacturers is so expensive. Always looking for high value, which is very subjective I know. I will be following along. That’s a huge space to conquer
Best
No kidding!!
It's why I started this thread. A high budget system in a room like my studio (420sf, sloped ceiling) or even double the size would be easy, familiar territory. This is borderline PA. The primary listening area isn't that big, but when there's a party, then it's naturally going to get cranked up & the system will have to sound at least OK beyond the immediate area.
@mikessi wow that house is amazing as are all your projects! Someday I need to post some pics so y'all can see how we bumpkins do it. Gotta go feed the pigs and practice on my jug bass now and check my squirrel traps fur supper.
In my last home I had a very large vaulted space that I filled with sound using a system consisting of a 3-way dipole type loudspeaker operating above about 80Hz and sealed subs below. I deployed stereo subs, with four 12" drivers per side each in their own cube of about 1.25cuft. I stacked them on top of each other into a column and placed the columns against the wall behind the speaker. The speakers were positioned about 1.5-2m out from the wall. The system was active with DSP used to implement the crossover and address the main LF room mode.
With a 3-way dipole you can get down to around 100Hz using a single 12" or 15" driver, or use four 8" drivers in a panel arranged 2x2. The midrange can be a 6" class which can cover 350Hz to about 2kHz, with a dipole tweeter above like Mundorf or I used Aurum Cantus ast2560 or ast25125 with the faceplate removed. For my systems the mid and tweeter were nude. This can reach pretty good SPL levels with the woofer relived of low bass duty.
This concept could work well in the space that is shown in the first post.
With a 3-way dipole you can get down to around 100Hz using a single 12" or 15" driver, or use four 8" drivers in a panel arranged 2x2. The midrange can be a 6" class which can cover 350Hz to about 2kHz, with a dipole tweeter above like Mundorf or I used Aurum Cantus ast2560 or ast25125 with the faceplate removed. For my systems the mid and tweeter were nude. This can reach pretty good SPL levels with the woofer relived of low bass duty.
This concept could work well in the space that is shown in the first post.
Thanks for sharing your solution, Charlie.
It's not far from what I've planned, tho the # of subs you used is way more. We will adjust as the system gets assembled.
The primary difference is the low frequency driver in the OB. I've planned on the 9.5" SBA Textreme, but do have both 12 & 15" pro drivers on hand.
I'll start with a modular OB setup kind of like the pureaudioproject designs so those drivers can be swapped in/out easily.
It's not far from what I've planned, tho the # of subs you used is way more. We will adjust as the system gets assembled.
The primary difference is the low frequency driver in the OB. I've planned on the 9.5" SBA Textreme, but do have both 12 & 15" pro drivers on hand.
I'll start with a modular OB setup kind of like the pureaudioproject designs so those drivers can be swapped in/out easily.
Mark's house really is amazing. I've never seen anything quite like it before. Mark harvested the lumber for the beams, milled them and had them installed himself when the house was being built. The view from his house of the southern bay is stunning & you can see clearly out to Mt. Baker in Washing state (11k' tall, 125km west). There's are lots of hardy, talented DIY types here, but Mark takes the prize among the people I know. He has a 2000sf 2-storey 100' long Quonset hut workshop that is utterly full of heavy duty tools (including 7 different welding machines & a plasma cutter with a 4x8 bed & a full-size ventilated car painting space).
The island I live is very forested still (mostly Douglas fir, cedar, arbutus, alder) & more so in the past. Climate change is knocking down the trees a lot faster than before.
Not sure my projects are quite so amazing; there are lots more capable designers/builders here. I mostly copy, borrow, beg, try not to steal and fumble/stumble/fake it till it turns out. 😉 When I'm not working on audio projects, I plant garlic, help my honey with the greenhouse & veg gardens, fight beavers chopping down our fruit trees, chop wood for the wood stove...
Was this overkill for headroom or just enough? Did it give you balanced FR at the listening area? How was the sound beyond the listening area? Any pics or measurements?
Whether that many subs is overkill depends on the drivers used. I made the mistake of choosing some pretty cheap GRS drivers just because I already had the cabinets from a buyout and the drivers fit the recessed hole in the cabinet that was designed for "old school" 12" driver frames, and now the normal frame OD is about 0.125 larger and most 12" drivers would not fit. My listening space was pretty large because of an open plan home and dimensions up to 40 feet across, so eight 12" drivers was not overkill and the sealed subs could provide satisfying bass better than dipole type subs below 35 Hz. See attached pics for the room and speakers. I could only find one pic that shows the subs. They were just utilitarian subs, nothing special, but they did their job. In any case I did not think of taking pictures of them per se, so they only happen to appear in the background of other pics.
The first two pics are from when our home was up for sale last spring. The subs were normally positioned on either side of the rock fireplace hearth but I took them out when we were showing the home to potential buyers. IMO when in this position they disappeared nicely into the area and centrally located them along the long wall of the room. In a more regular sized room I would put them in the corners if possible and then use some delay compensation for the main speakers. I liked how the speakers could disappear and did not draw one's eye too much. Contrast this with some larger planar OB systems e.g. from PAP which are not my style or design approach for a dipole loudspeaker. But it's not a look for everyone...
The nice thing about a true dipole system is that the FR seems about the same everywhere. I could walk around the immediate area or even be farther away in the house and except for the HF the tonal balance remained the same. This is because a dipole with flat FR will also produce a flat power response. There is always some attenuation of the HF due to adsportion by room surfaces, however. Otherwise I tend not to use room treatment and prefer a more live/reflective environment with a dipole speaker.
The first two pics are from when our home was up for sale last spring. The subs were normally positioned on either side of the rock fireplace hearth but I took them out when we were showing the home to potential buyers. IMO when in this position they disappeared nicely into the area and centrally located them along the long wall of the room. In a more regular sized room I would put them in the corners if possible and then use some delay compensation for the main speakers. I liked how the speakers could disappear and did not draw one's eye too much. Contrast this with some larger planar OB systems e.g. from PAP which are not my style or design approach for a dipole loudspeaker. But it's not a look for everyone...
The nice thing about a true dipole system is that the FR seems about the same everywhere. I could walk around the immediate area or even be farther away in the house and except for the HF the tonal balance remained the same. This is because a dipole with flat FR will also produce a flat power response. There is always some attenuation of the HF due to adsportion by room surfaces, however. Otherwise I tend not to use room treatment and prefer a more live/reflective environment with a dipole speaker.
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Also, I have used four of the WO24P per side as a dipole woofer system in a panel just large enough to fit them, and they are fantastic. Clean all the way up to Xmax and until you bottom them out! But still not really producing enough SPL below 40Hz as a dipole in a small baffle. I crossed them over to a mid around 300Hz.
If your customer is interested in dipole all the way down, there is a great driver by OneAudio in Vegas called the IB318 (an 18") that has 36mm Xmax Fs=24Hz and Qts=0.72. I used this in a U-frame and was very impressed, but I had to dismantle it before the move. I have plans to re-use this driver, for sure... loaded into a U-frame one or more of them can do dipole bass to 20Hz but need about 1kW each to take advantage of the driver's capabilities (e.g. to reach Xmax when used OB). The only negative is some motor noise from the gap venting but I think this can be remedied by directing that through/via a vented magnet cover. Small company and the owner is nice and likes OB. See:
https://www.oneaudiousa.com/product-page/ib3
If your customer is interested in dipole all the way down, there is a great driver by OneAudio in Vegas called the IB318 (an 18") that has 36mm Xmax Fs=24Hz and Qts=0.72. I used this in a U-frame and was very impressed, but I had to dismantle it before the move. I have plans to re-use this driver, for sure... loaded into a U-frame one or more of them can do dipole bass to 20Hz but need about 1kW each to take advantage of the driver's capabilities (e.g. to reach Xmax when used OB). The only negative is some motor noise from the gap venting but I think this can be remedied by directing that through/via a vented magnet cover. Small company and the owner is nice and likes OB. See:
https://www.oneaudiousa.com/product-page/ib3
Charlie, what's the benefit of having the four wo24 mounted in two baffles in tandem like this? Does it get additional output compared to two in a single baffle? I get you get reduced distortion compared to two drivers.
There are two baffles. Let's call them the front baffle and the back baffle for convenience. Each in itself is a dipole consisting of two drivers in a planar baffle. Using two of them is just placing two dipole sources in proximity to each other, just like using two drivers in a sealed box. And likewise, at low frequencies when the distance between them is small compared to the wavelength, they will add coherently. As frequency increases you get to a frequency where the distance between them starts being more than 1/4 wavelength, and on axis and above that frequency there will be dips (destructive intereference) and higher in frequency a peak again (constructive interference). As long as you keep the passband below the first dip, you get the advantage of twice the radiating area (+6dB SPL) but front the front the "size" of the baffle looks about the same. You could potentially use N drivers in this way, as long as you account for how they will interefere as frequency increases. Also, by keeping the drivers at the floor level you get boundary reinforcement up to a higher frequency compared when the woofer is located above the floor by e.g. 12" or more. In this setup I was able to cross over at about 300Hz with the front and rear baffles separated by about 10" -12" although I forget the exact distance. The speaker pictured actually uses four 10" drivers by Scan Speak, but the SB Acoustics WO24P would work out about the same since it is a 9" or 9.5" driver IIRC. With the woofers at the floor only the midrange and tweeter are up above the floor where they are more visible, and this tends to reduce the "visual footprint' of the loudspeaker no matter whether you use a small baffle or the nude approach I am using in this system
In this configuration I did get 2nd order distortion reduction by mounting the drivers in the rear baffle opposite to those in the front baffle, e.g. the front two point forward and the rear two point backwards and all four magnets are in the middle between the two baffles.
In this configuration I did get 2nd order distortion reduction by mounting the drivers in the rear baffle opposite to those in the front baffle, e.g. the front two point forward and the rear two point backwards and all four magnets are in the middle between the two baffles.
Thanks for all the info, Charlie. Your old space looks awesome, btw! LM guess -- the new space is similar?
OK, so less than ideal woofers, hence 8 of them.
I'm not confident that OB all the way into the bass is feasible in Mark's space w/o blowing the budget. Four SBA SB34SWPL76-4 12" subwoofers are on order & they could be set up as single sub units rather than dual-opposed. Or maybe 2 more for 4 subs + 2 woofers in the primary speakers. I might consider a pair of the SB Audience Nero-15SW800 if I get the DSP setup to work well enough for <25Hz. Still haven't had time to refine the sub I built with one.
Your wire frame OB setup could be interesting to try in my studio but for Mark, WAF dictates a more traditional look, and the design of my old Orions was deemed the most non-traditional look that would be acceptable.
I'm a bit surprised that the SBA SB34SWPL76-4 isn't discussed more here (at DIYaudio) because on paper it's quite the driver for an old time "acoustic suspension": 15mm Xmax, 19Hz, 79l Vas -- WinISD predicts~40 liter sealed box for 0.7 Q w/ F3: 43Hz & F10: 25Hz. DSP would easily flatten the response to 25Hz, with 300W power handling. From a box under 1.5cf, that's pretty impressive, and the cost relatively modest at Solen: CA$332 = USD237
I plan to drive the subs with 2x300W class-D amp modules by @Erica.C At USD100 a pop, they are cheap enough to try bridged for 600W, tho the 4ohm impedance could be an issue. So far, the dozen or so amp modules I've got from Eric have performed well w/o issues & are sonically difficult to differentiate from Hypex NC252MPs. They are noisier, but any concern about SN/noise is moot because <120Hz, it will never be audible.
OK, so less than ideal woofers, hence 8 of them.
I'm not confident that OB all the way into the bass is feasible in Mark's space w/o blowing the budget. Four SBA SB34SWPL76-4 12" subwoofers are on order & they could be set up as single sub units rather than dual-opposed. Or maybe 2 more for 4 subs + 2 woofers in the primary speakers. I might consider a pair of the SB Audience Nero-15SW800 if I get the DSP setup to work well enough for <25Hz. Still haven't had time to refine the sub I built with one.
Your wire frame OB setup could be interesting to try in my studio but for Mark, WAF dictates a more traditional look, and the design of my old Orions was deemed the most non-traditional look that would be acceptable.
I'm a bit surprised that the SBA SB34SWPL76-4 isn't discussed more here (at DIYaudio) because on paper it's quite the driver for an old time "acoustic suspension": 15mm Xmax, 19Hz, 79l Vas -- WinISD predicts~40 liter sealed box for 0.7 Q w/ F3: 43Hz & F10: 25Hz. DSP would easily flatten the response to 25Hz, with 300W power handling. From a box under 1.5cf, that's pretty impressive, and the cost relatively modest at Solen: CA$332 = USD237
I plan to drive the subs with 2x300W class-D amp modules by @Erica.C At USD100 a pop, they are cheap enough to try bridged for 600W, tho the 4ohm impedance could be an issue. So far, the dozen or so amp modules I've got from Eric have performed well w/o issues & are sonically difficult to differentiate from Hypex NC252MPs. They are noisier, but any concern about SN/noise is moot because <120Hz, it will never be audible.
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It sounds as though your upper frequency plans are pretty locked down, but as an alternative--the Radian 5208c and 5210 coax units are 95-96 db and handle a few hundred watts for the low end. Likely enough for that space, especially if kept to 300 Hz, and good directivity.
It's interesting how a huge space in one context is small in another.
That One Audio driver is neat. I have no feeling for when large, heavier cones do or don't work well for music vs HT. Or where PA effectively starts and stops.
This 100 lb / 45 kg cutie from Stereo Integrity is a 24" IB driver with a claimed 72 mm one way xmax (70% BL) and 93 db. About the 3.5x the Vd of even the impressive IB3 18". One guy apparently mounted an IB-24 in his truck. 😳
It's interesting how a huge space in one context is small in another.
That One Audio driver is neat. I have no feeling for when large, heavier cones do or don't work well for music vs HT. Or where PA effectively starts and stops.
This 100 lb / 45 kg cutie from Stereo Integrity is a 24" IB driver with a claimed 72 mm one way xmax (70% BL) and 93 db. About the 3.5x the Vd of even the impressive IB3 18". One guy apparently mounted an IB-24 in his truck. 😳