Hornresp (when you view the "Schematic Diagram" tab) gives a cross section of a conical (rotationally symmetrical) horn. So the areas are whatever width is shown squared, and then multiplied by pi/4.
Labsub is a decade old, true, but the math and physics have not changed. The Lab design (before it was folded) is still up near the top of the heap. As far as I can see, despite what people are saying, the music hasn't changed all that much in the last decade either - but then again I always did search out the bassy stuff. I currently have a 35 hz sub and I don't feel like I'm missing anything with music, including dubstep and dance (although my library is limited, I haven't needed to set a steep high pass filter so I haven't done it and I haven't actually put all my music through a program to see if there's anything in the material low enough that I wouldn't even know if it was missing).
My point here (and I don't want to push it too far but it IS worth mentioning) is that I still can't believe a stack of Labs isn't low enough for music playback. Since I don't know your technical level of knowledge I'll leave it to you to question whether your music really goes as low as you think it does and whether your high pass filter is actually set properly, if it's set just a few hz too low it's pretty much useless.
Then there is the issue of the Labhorn itself. If you built it from the official plans it's not a really great sub. Here's a measurement directly from the official labhorn site.
http://www.prosoundweb.com/lsp/response1.gif
See the big dip at around 45 hz? That is due in large part to the fact that the rear chambers are much too small, much smaller than the original design call for. There was a mistake in folding that was never corrected. That dip will get worse with power compression too, so at the end of the night after hours of soaking up thousands of watts you are going to have a big hole in response at around 45 hz. (The room itself could help or hurt this situation - but that's a whole other topic.) I suspect your problem could be bad response above tuning, not lack of 25 hz response. But then again I don't know your technical level and I don't want to insult you, so I'm not going to discuss any of this further unless you want to.
Firing your stack of Labs into a corner will make it sound like you have twice as many subs with twice as much power (at least in theory. There will be significant gains even if not the theoretical maximum.) Is this an option at all? Do you have a good available corner, preferably concrete or brick? Even if you have to rearrange the room a bit it might be a lot less expensive and time consuming in the long run. But I don't know anything about your room and this is not the fun part of this intellectual excercise, so I am not going to bring this up again, unless you want to talk about it.
Ok, I was just wondering whether this was a home, bar or concert type setup. I'm not familiar with the amps, could you tell me how much power they put out and their comfort zone as far as impedance range?
5000 euro is about $10000 US, no? That sound incredibly expensive for 4 Labs. Here in Canada I can make a single Lab for about $600 - $1000 depending on the type of wood used and the finish. Did you have them custom made or is stuff just incredibly expensive over there?
Which brings me to my next point, I have no idea which drivers are available to you. Usually what I would do is simulate all the top contenders in my price range. In this case I don't have time to do that and I also don't have any idea what's available.
Cab size is whatever you make it. For a tuning that low, a full size classical horn is going to be large. Please consider my notes above and just confirm that you actually do need tuning that low.
Hornresp will give us an excellent resource. I can export the flare data as a chart showing cross sectional area at increments of length along the horn path. This is more than you need as far as dimensions are concerned, but you still need to know how to fold properly. There are tutorials but be aware it's not a fast or easy job.
And speaking of Hornresp, are you getting anywhere with Hornresp or have you given up? If you have any questions or need help, please ask. Learning how to do this yourself is invaluable (IMO) but if you can't or just really don't want to I'm not going to push it.
I'm going to work on a couple of preliminary simulations so you have something to look at, I'll post up some pics soon.
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The labs:
The block of 4 labs souds impressive, fat en low… until.. I take the high pass of and set my parametric to 28 Hz / Q .7 and beef it up some 10db.. than… holy cow!!! that is what I want!! But with the labs that reduces the powerhandling to… 50% maby even less.. there is something down there just below 30 that makes it “uber”-low.. with the righ programm material that is…
The lab-horn:
Mine are buit according the official plan.. inclusive the flaw so to say… I think they had to compromise the rear chamber because of the size restriction they had set themselfs.
Corner loading: that works great.. can turn op sounding boomy if you are not carefull…
but in this case no corner available..
The amps:
http://harmonicresolution.com/I-Tech%20Specifications.htm
http://labgruppen.com/media/downloads/product/TDS-FP10000Q_V5.pdf
Cost:
4 labs cost me aroud 5000 euro (6500 US dollar) in Warnex finish, that is NOT self made and NOT self sprayed I had to hire and pay people for that..
Drivers:
Is this a top contender?
http://www.faitalpro.com/products/schede/hps.php?id=201050120
or this?
http://www.bcspeakers.com/product.php?id=46
Cab size:
something around 60x48x28” like in my scetch at the beginning of the thread… it must be possible to fold a serious horn in that size..
Hornresp:
I like to learn it.. I gave it a short try, but did not have the time this weekend…
next weekend is hornresp time.. perfect that it gives the exact dimensions at any given length along the horn.. i’m looking forward to learn it.. from my short try I know that I will have many questions I am aware that i takes time.. learning hornresp and the folding..
I’looking forward to you’re preliminary simulations… thanks so far
Best regards
Jan
The block of 4 labs souds impressive, fat en low… until.. I take the high pass of and set my parametric to 28 Hz / Q .7 and beef it up some 10db.. than… holy cow!!! that is what I want!! But with the labs that reduces the powerhandling to… 50% maby even less.. there is something down there just below 30 that makes it “uber”-low.. with the righ programm material that is…
The lab-horn:
Mine are buit according the official plan.. inclusive the flaw so to say… I think they had to compromise the rear chamber because of the size restriction they had set themselfs.
Corner loading: that works great.. can turn op sounding boomy if you are not carefull…
but in this case no corner available..
The amps:
http://harmonicresolution.com/I-Tech%20Specifications.htm
http://labgruppen.com/media/downloads/product/TDS-FP10000Q_V5.pdf
Cost:
4 labs cost me aroud 5000 euro (6500 US dollar) in Warnex finish, that is NOT self made and NOT self sprayed I had to hire and pay people for that..
Drivers:
Is this a top contender?
http://www.faitalpro.com/products/schede/hps.php?id=201050120
or this?
http://www.bcspeakers.com/product.php?id=46
Cab size:
something around 60x48x28” like in my scetch at the beginning of the thread… it must be possible to fold a serious horn in that size..
Hornresp:
I like to learn it.. I gave it a short try, but did not have the time this weekend…
next weekend is hornresp time.. perfect that it gives the exact dimensions at any given length along the horn.. i’m looking forward to learn it.. from my short try I know that I will have many questions I am aware that i takes time.. learning hornresp and the folding..
I’looking forward to you’re preliminary simulations… thanks so far
Best regards
Jan
Attachments
Ok, this clears up a lot, now I understand that you do have material that can benefit from a lower tuning.
No, this was just a simple mistake. I have some of the original posts that Danley made while designing the horn and he clearly admits that he folded it on paper and did not realize until someone sketched it up in CAD that the rear chambers were smaller than he expected them to be. He says that filling the pointy area in the chambers with stuffing will fix this to some extent but my simulations clearly say otherwise. No one ever bothered to refold the horn properly, although there were several Labhorn derivative designs that changed other aspects. If you want the original Danley posts I can try to find them.
The boominess is a design factor. If it's designed to be corner loaded then boom should not be a problem unless it's coming from the room. Regardless, eq can be used to calm the boom. But since you have no available corners there's no need to discuss this further.
Thanks, I'll look at this when I get a few moments.
I'll look at these drivers. Like I said though, the LAB12 is a very good driver and I'll simulate with that first. Is it available and affordable over there?
Thanks for your patience, I got busy today but I'm hoping to have something for you tonight.
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Hello jag.
You are right.. I remember those posts by Danley.. I think that I also stil have them somwhere.. I also think he kept close to this fold because he already had that from the BT7 I think I would have done the same...
Probably all drivers are available here no problem, inclusive the Lab12
The drivers I mentioned however have more than double the powerhandling.. but than again I don't know if the other horn-specific parameters for these are ok... bottomline is the most suitable and powerful driver to create an eartshaker 8x12 horn...
And.. take you're time.. there is no hurry.
best regards
Jan
You are right.. I remember those posts by Danley.. I think that I also stil have them somwhere.. I also think he kept close to this fold because he already had that from the BT7 I think I would have done the same...
Probably all drivers are available here no problem, inclusive the Lab12
The drivers I mentioned however have more than double the powerhandling.. but than again I don't know if the other horn-specific parameters for these are ok... bottomline is the most suitable and powerful driver to create an eartshaker 8x12 horn...
And.. take you're time.. there is no hurry.
best regards
Jan
The snailshell shape fold is very elegant and works very well in this case, it has a lot of advantages, like for example it keeps the throat aspect ratio small, which is a very good thing in terms of velocity issues. Also there are very few bends and only one 180 degree bend. It also keeps the last bend 4 feet back from the mouth, which helps to reduce the amount of wasted space in the corner.
If I could change 1 thing about the Lab it would be to make the rear chambers larger, it would require a complete refold but it's a small price to pay.
If I could change 2 things about the Lab I'd fix the rear chamber size and mount the drivers in a push/pull configuration.
Other than that that the Lab is a beautiful thing.
As far as power handling is concerned, in general the lower you tune the less power handling you need, since you hit xmax sooner.
But I will point this out now and be very clear about it - I've never built a Lab or tested one, all the info I have is from the internet, and much of it was posted by people that didn't like the Lab (or were selling a comparable product or cooling device), so I have no idea how real the power handling problem is in real use with real music and properly protected with a high pass filter. Also, when I do designs and build them, I don't usually test how well the power handling in reality relates to the simulation - I've never had any need to bother.
Also, as you may or may not know, power handling AND xmax are usually a spec invented by the marketing dept, not a spec measured by the engineering dept, so it's hard to tell how hard you can push any given driver if you don't have previous experience with it, or at least have a general idea how the manufacturer came up with these specs.
This is the main reason I want to keep all my cards on the table so people that are smarter and/or more experienced than I am can check my work.
Sorry for the delay, simulations coming soon.
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This sounds like fun
a horn where the total mouth size matches the tuning frequency of the horn cant really be a bad thing....
if you are planning to go on with this large project you could try many differing designs to create the 25hz wavelength "block"
just be sure to plan it right, as there is a lot to be done before it can be tested seeing as you will need to have all the horns up and working.
I like it keep playing
a horn where the total mouth size matches the tuning frequency of the horn cant really be a bad thing....
if you are planning to go on with this large project you could try many differing designs to create the 25hz wavelength "block"
just be sure to plan it right, as there is a lot to be done before it can be tested seeing as you will need to have all the horns up and working.
I like it keep playing
An externally hosted image should be here but it was not working when we last tested it.
Ok, let's start here. It's kind of awesome that you already own Labs and I already have a Lab sim done up so we can use the Lab as a baseline.
As shown this is Danley's original design (before folding), shown at 1 watt. It's 750 liters internally (not including the wood or dead spaces in the corners but that does include all the chambers and the flare). It does not reach xmax until about 1600 watts total per cab (about 2x the drivers' power rating).
The first graph shows 1 cab in 2 pi space. (Most of the graphs I will show will be in 2 pi space. Even though that does not reflect your exact situation it makes it easy things easier to show everything in 2 pi.) The second graph is 4 cabs in 2 pi so you can see how multiple cabs affects things. The second graph could also be interpreted a a single cab placed in a perfect corner - in reality there is no such thing as a perfect corner so you won't get quite that much boost but it does demonstrate the power of corner loading.
(Please note that it's been awhile since I entered this simulation into Hornresp so while I think this accurately reflects the original design I'm not going to guarantee it, and I'm not going to do the unit conversions to make sure. Anyone interested can do this themselves, I already posted the details of the original design earlier, quoted straight from Danley's posts.)
EDIT - I guess you have to click the pic and then click the lower left corner to see it full size. I host my pics externally so you don't have to do that, but I guess this forum works different.
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An externally hosted image should be here but it was not working when we last tested it.
Moving on, this is a very rough simulation of the Labhorn after folding. This is rough because it was done very quickly just to get a rough idea and I didn't bother to measure the plans very accurately, I just used a printed pic and a ruler to estimate my cross sectional area at selected points along the line. Still, it's more than good enough to see what happened when it was folded, and to give an idea how Labs perform.
Unfortunately I don't have enough segments in Hornresp to get a more accurate simulation, so I showed 2 graphs. The first graph shows the horn as Nd (driver and throat chamber come before the throat) and the second graph shows the horn as Od, but the driver in the simulation is a few inches further down the line than it is in the plans, again due to the restriction placed by Hornresp on the number of segments. The actual response will be somewhere between these 2 graphs. A more accurate model could be done in Akabak but I don't think it's worth taking the time since we are just using the Lab as a baseline anyway.
The design shrunk significantly during folding, it's only 620 liters internally now, fully 130 liters less than the original design. Both graphs are shown at around 1600 watts, which is what it takes to push the drivers to xmax. I'm not sure how much power the drivers will actually take, but if you want to imagine it at 800 watts (the driver's rated limit per cab) just subtract 3 db. Both graphs show a single cab in 2 pi space, based on the graphs in the preceding post you can extrapolate in your mind what a stack of 4 would look like.
Now that you can see what you actually have it should be easier to identify what you want as we proceed. We're done with the Lab now and I'll start simulating the janhorn.
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I took a minute to look at the drivers you linked to. The B+C has considerably less xmax than the LAB12, so the high power handling won't gain much. The Faital has a similar xmax rating to the LAB12, but the Faital's xmax is defined by a formula based on gap height, NOT linear excursion as measured by a Klippel so there's really no way to know how much linear excursion there is or how it would compare to a LAB12. Furthermore, I don't know how Eminence defines xmax either, so can't reliably compare the LAB12 to other models outside the brand.
As you can see, some topics don't have clear answers unless you actually buy all the drivers and do your own independent head to head comparisons. And even then, for a project like this you can't test them as they will be used anyway. There's risk here in choosing the right driver.
As you can see, some topics don't have clear answers unless you actually buy all the drivers and do your own independent head to head comparisons. And even then, for a project like this you can't test them as they will be used anyway. There's risk here in choosing the right driver.
An externally hosted image should be here but it was not working when we last tested it.
Here's a first stab at it. I cheated and did this the easy way. I used the previous Labhorn design and changed only 2 things. I increased the horn length by 124 cm (which actually changes the whole flare but Hornresp does the hard work) and increased the rear chamber size (total for both drivers) to 100 liters.
As you can see, the LAB12 really comes into it's own here with this lower tuning, now the xmax and power handling run out at the same time (on paper at least - shown at 800 watts). In this design none of the driver's potential is wasted.
The horn is now 1068 liters net per cab, which will amount to a bit less than the volume of 2 Labhorns when built. Each cab still houses 2 LAB12 drivers. As shown the first graph is 1 cab in 2 pi, the second graph is excursion (which also shows tuning) and the third graph is a stack of 4 cabs in 2 pi OR a single cab in a perfect corner.
At this point (it has to come sooner or later) I'm going to advise against trying to cram so many drivers in your cabs. Horns are not about cone area, the cab volume does the work. You can go the other way but I don't see the point. As you can see, 4 of these are already very loud. I'll include a pic of 4 regular Labs at xmax below so you can compare (same rough model as above but 4 cabs), but remember, at xmax the Lab is fully 2x past the driver's power rating at this level and will be well into power compression and possibly on fire - subtract 3 db if you want to see it only powered with 800 watts. This new horn (x4 cabs) is not as loud due to the lower tuning but I think this is already good enough for your needs. If you use 32 drivers your building is actually going to break. But this is the point of compromise - you can't add too many more cabs before dispersion starts to narrow, but that also depends on how high you plan to run the subs. If you want a higher crossover point you might want to use more drivers per cab than shown but I don't think you need 32.
An externally hosted image should be here but it was not working when we last tested it.
Now a few final notes to finish up this preliminary example. This is not necessarily a great design, I spent less than 10 minutes on this. In fact it takes me longer to host the pic and type a few words about it than it takes to do the sim. This sim is end loaded, but more work needs to be done, it needs to be simulated as an offset driver horn (no horns are truly end loaded, they are always offset to some degree).
Now tell me what you want to see and I'll show you - different drivers, different cab dimensions, more drivers per cab, whatever. But I've shown you enough in my Hornresp screenshots to get you started in Hornresp yourself, so I encourage you to start that when you have time.
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Try it with a TC Sounds Epic 12
I'm guessing it would cost a small fortune in shipping to get a bunch of Epics to the Netherlands, there's probably no local distributor like there is for Eminence, Faital and B+C. In any case there are any number of directions we could go with this, driver selection being only one. I don't want to spend too much time on this until I get some feedback from the OP about what direction he wants to go.
As it stands, a stack of 8 cabs of the revised, lower tuned Lab design I showed will be as loud as the 4 regular Labs he already has, and will extend down to 25 hz as requested. It's not what he asked for exactly as far as the drawing in post #1, but as far as specs go it is what he asked for. He specifically says he adds 10 db of boost below tuning, which is a disasterous situation as far as excursion is concerned.
(Talking to jan1 here - ) In my last post I showed an excursion graph. As you can see, below tuning excursion skyrockets, and if you defeat the high pass and add 10 db of boost below tuning, excursion limited power handling drops like a rock so you won't get much max spl potential at all down there.
You already said the Labs are loud enough, they just don't go low enough, this design (8 cabs housing 16 drivers) will be just as loud as your current stack of 4 regular Labs but extend down to 25 hz.
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Jan1,
As much as I like FLH, their big problem is they have to be huge to go low.
TH don't, which is why Danley currently only has one FLH in the sub line up.
He gave away the FLH Lab design (similar to his BT7, which was similar to the original Cerwin Vega Earthquake FLH) when he came up with TH.
A TH also works well with a low corner below FS.
Also, much as I like the Lab 12, going with a speaker like the B&C 18SW115 or the less expensive ceramic magnet BC18TBW100 will replace at least three to one due to the increased excursion and far better heat removal.
A pair of Lab 12 is slightly more sensitive, but the 18SW115 more than makes up the sensitivity once the driver gets hot, it can handle four times the power and hardly get warm, while the Lab 12s feel like waffle irons.
As Just A Guy has pointed out, little has changed in horn design (other than TH
), but a lot has changed in LF driver design in the last several years. The Lab 12 was near the top of the heap last century, but not so much now.A parting thought, my Keystone sub design has a low corner around 37 Hz, which I find is a good compromise between size and sensitivity, but can also have a lower corner (with less sensitivity) by simply reducing the mouth size. I have thought about having a "step down" panel to T-nut on for shows requiring sub 32 Hz action, but so far have not found a genre needing that much LF.
Art Welter
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That's only true if you use a real horn flare (as defined by the old math) but that's not really necessary. As I mentioned back on the first page, I can consistently beat tapped horns max spl with a front loaded horn of the same size, with the same low frequency rolloff, and the front loaded horn will actually have smoother response too. OP is prepared to provide as much space is required anyway, so even if a tapped horn could be designed to be smaller and better than a front loaded horn, the smaller size wouldn't really be a benefit, especially considering that it's a permanent installation.
I don't think that timeline is right, he designed the Lab long before he came up with TH. And he designed it specifically as an open source project with all details published in real time step by step as he designed it, so he didn't really ever formally give it away, it was public domain before he even started to design it.
So does front loaded horn.
As I pointed out, power handling might be a problem in regular Labs but it won't be a problem when you tune 10 hz lower.
Regardless, I will admit you have a lot more experience than I do with all these drivers, so in general I'm inclined to trust your opinion.
How much compression ratio can those big cones handle?
And am I mistaken or did you actually prefer your horn sub design with dual LAB12's in favor of a single larger driver? (I read your thread a long time ago, I might be mistaken.)
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An externally hosted image should be here but it was not working when we last tested it.
That's the bc18tbw100 in the same horn as shown above (x4 cabs in 2 pi), except the rear chamber had to increase in size by 100 liters, shown at xmax with 1000 watts.
Looks very nice, Art knows his drivers. (To be clear though, the same enclosure with 3 LAB12's would outperform this by a bit.)
(No offense to DrDyna that I did this sim but not the epics, but I already know what the epics will do and I was curious about the b+c that Art likes.)
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None taken, I didn't read enough of the posts to know sourcing the driver might be an issue.
The only reason I brought it up at all was the fact that I used the TC sounds drivers in my tapped horns that were originally designed for the Lab12. The sim said they'd go lower and handle more juice, so I thought it might be a solution that could work in this case as well.
There's another consideration too, when choosing drivers for this type of design - long term availability. TC Sounds has a bad habit of going out of business every once in awhile, and even if they didn't I doubt they will still stock the same models 10 years from now. The LAB12 has been available for a decade and there's no reason to stop producing it - it's popular and works in a variety of situations. I don't know B+C's history, but at least they are a pro manufacturer, and the pro market manufacturers don't switch up their models and obsolete the old ones nearly as fast as home market manufacturers like TC.
Having said that, the Epics do perform. (On paper at least, I've never seen one in person and don't know how they stand up to power compression at huge power levels.)
Hi Jan,
Art raises a valid point. Last I checked the LAB12s were going for about 240€ a piece here in Germany - about twice the 170$ they cost in USA. On the other hand, for less than the price of two Labs, you can get even the beefy Neodymium magnet B&C 18SW115 - as well as several other B&C 18s for a bit less. Last time I looked they were all hovering around 400€ - which is excellent value for these drivers.
Your size restriction would allow nicely for a dual driver symmetrical big tapped horn, like the Danley TH221. In fact the folding is almost identical to your FLH design, only without the rear chamber. Something like this with two 18SW115s would push some serious air.
By my calculation your enclosure is about 1000 liters, a tapped horn this size tuned for 25Hz (420cm total path) will go a long way: 131dB from a single cab, and 142dB from 4 cabs. And that's flat down to 25Hz. (High pass needed around 22Hz). A real rudimental Hornresp input to get people started - not yet adapted in any way to fit the exact dimension requirements, just same overall size.
4 Cabinets:
Art raises a valid point. Last I checked the LAB12s were going for about 240€ a piece here in Germany - about twice the 170$ they cost in USA. On the other hand, for less than the price of two Labs, you can get even the beefy Neodymium magnet B&C 18SW115 - as well as several other B&C 18s for a bit less. Last time I looked they were all hovering around 400€ - which is excellent value for these drivers.
Your size restriction would allow nicely for a dual driver symmetrical big tapped horn, like the Danley TH221. In fact the folding is almost identical to your FLH design, only without the rear chamber. Something like this with two 18SW115s would push some serious air.
By my calculation your enclosure is about 1000 liters, a tapped horn this size tuned for 25Hz (420cm total path) will go a long way: 131dB from a single cab, and 142dB from 4 cabs. And that's flat down to 25Hz. (High pass needed around 22Hz). A real rudimental Hornresp input to get people started - not yet adapted in any way to fit the exact dimension requirements, just same overall size.
4 Cabinets:
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The Lab 12s had a dip in the response around 60 Hz in the Keystone.
I far preferred the BC18SW115 to the Lab 12 in the TH, less power compression, lower distortion (though not by much) and a smoother frequency response.
That said, the design was optimized for the BC, not the Lab 12s, though they did pretty well.
I used a 2.5 to 1 compression ratio in the Keystone, distortion was still low using 1500 watts of sine wave in to the BC18SW115.
I'd think a 3 to 1 would still offer no problems at 15mm excursion.
You could pretty much drop the BC18SW115 or BC18TBW100 in to your FLH (or the LabHorn) design and get way more real output.
Just looked at the Hornresp sims for the BC18SW115 Keystone vs. the 12Pi, which is similar to the Lab sub, but larger, more than twice the size of the Keystone.
The 2xLab 12 Keystone sims at 128 dB at 37 Hz.
The 2x12" 12Pi sims 131 dB at 35 Hz.
The BC18SW115 Keystone sims at 132 dB at 37Hz.
The 12Pi design with the BC18SW115-4 sims at 137 dB at 38 Hz.
I'm sure the FLH could be optimized better, I just dropped the speaker parameters in and did not change anything else.
When power compression is considered, my experience is the BC18SW115 will outdistance the Lab12s by at least another 1-2 dB over the above figures, but it takes more power to do it.
P.S. James, if the Neo B&C 18SW115 is less than the Lab 12s in the UK, the ceramic magnet BC18TBW100 would be even less- there is absolutely no reason to use the Lab 12s if starting from scratch when the better B&C drivers cost less.
Art Welter
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