[chipperman]

I know the collective wisdom on this site is going be a great help. I am going to build two subs, one going into an inside corner, the other on the apex of an outside corner. The total space volume is 3200 cu. ft., with three doors ( open passages) emptying from the room on one side. The room has a 12 ft. vaulted ceiling with the beam running parallel to the front wall where the units will sit. The WAF is a big problem here (isn't it always?). While it will of course be used for theater, my main concern is for musical accuracy and deep extension for organ pipes, cello, etc. I do not listen at deafening levels, even the reference level for THX exceeds my pain threshold. I crossover at 40 to 50 hz.

With two drivers I have no doubt I will build enough pressure. The question is vented or sealed. The upper limit of internal volume is 170 liters as that is where the mockup produced howling, which is one step below flying frying pans.

The drivers are 18" TC Sounds pro drivers, with the Neo magnets. The only place I've seen them used on searches is Basspig, but he is putting two to a cabinet. I don't have the T/S parameters yet, but I wonder if anyone has come across this anywhere? I believe they were also marketed as Bassmaxx ZR18 drivers.

Now, since power is cheap, and we could use a transform circuit if we have to, what do you think?
They will be equalized as best I can with the SVS/Audyssey EQ1.

Any ideas?

 

[clausdk]

I'm not entirely sure what the exact question is here?

Suggestions for WAF friendly cabinets?

If so, I think bottom end tables, next to the couch is possibly the finest way to fit a big cabinet into a living room.

If your woodworking skills are like mine then a sqaure cabinet isnt all that bad! Otherwise if you are very good at working with wood, I would go with a curved back similar in design as audiovectors subwoofers which are nice I think.

Personally I'm painting both of my 18" sub cabinets white hoping they will blend in nicely.

 

[Mike P.]

Post the parameters if you find them so we can see how it models or choose a sub that is more readily available. There are subs that work well in smaller cabinets with passive radiators if WAF is an issue, but that would depend on what your budget is.

 

[chipperman]

I should have been more clear. The object is not cost, it is a maximum size limit of 170 liters internal net volume. I am just not sure if I should go sealed or ported. I guess without the T/S numbers we come up short. I'll try to get some tomorrow. I already have these drivers, so we'll make them work somehow. The main speakers will sit on top of them, one at each end of the front wall.

 

[Mike P.]

Is there a model number on the sub?

 

[chipperman]

I am not where it is today (Father's Day). Bassmaxx calls it ZR18, but I can't find any data on their website. It is built for the pro market. I'll call TC Sounds in the morning and see if I can get the numbers.

 

[chipperman]

I tried to put this in before, but it said no links. I don't have any. Here goes again.
Numbers: 18" driver
Qts .291
Qes .301
Qms 9.246
Fs 25.732
Res 2.8 ohms
Ls 2.915m
Lp 4.933m
Rp 6.067 ohms
Dia 390m
Vas 218.4
mms 351.0
cms 108.9u
bl 22.98
n0 1.188
Sens 92.75db 1watt

 

[Mike P.]

We'll need the Xmax and power handling too. Is this a single or dual coil sub?

 

[chipperman]

x max quoted as 25 mm. It is a single coil, nomimal 4 ohms, with a nebulous power handling of 2000 watts or so. Is this enough information? I would, if possible, like a sealed unit just for the size, but we'll do what we have to. Thanks for all your help. The math on this just amazes me.

 

[Ricci]

Use those ported. They are a high efficiency, high power neo driver for pro audio or installed type sound. Not optimized for sealed really. I recently heard one of those(or very similar Worx TL.118.SS) and it has a very good sound to it. Try to tune it around 18-20hz with an 8" or bigger port.

 

[chipperman]

Thanks. I believe it is the same one made for Worx ( or Works, I don't know) for their pro apps. That is one big port! Do I need a refrigerator sized box?

 

[chipperman]

Ricci, I just read the Southern Subwoofer Shootout. I think that Worx unit is about what I would be building, but I didn't like the lack of ouput below 25 hz. You mentioned in the post that the curve didn't look good and that is why you filtered it. Will it play lower as is? If not, it looks like a sealed LMS Ultra would be better, especially with a linkwitz transform. I do no go for volume, but musicality, but I need to hit 16 hz cleanly. Since you heard both in a short time frame, could you discuss this a little more?

 

[Ricci]

The Worx was tuned to 25hz and we were pushing things very hard at the GTG so it needed a HPF to prevent the driver from bottoming out below tune. I generally reccomend a HPF with any ported, or resonant sub. The LMS sub is mine. Both can sound very good but have slightly different strengths. An LMS is more suited to a small sealed box and really deep bass while the neo 18 has higher sensitivity and is better suited to a ported enclosure with a bit higher tuning. They would be good in 9.5cu ft net each tuned to 18hz and would have more output than you would probably ever use from 16hz on up in room. Likely well over 120-125db. There is no reason that you couldn't use the neo 18's sealed though if you can't fit the big ported boxes. 3.5ft for each driver looks about right with a qtc of 0.550 and they would be good with around 1500-2000w per driver in that cab. You wouldn't need a HPF since xmax isn't exceeded until around 10hz and below. You would need an LT circuit or EQ boosting on the low end due to the sharp roll off of these drivers in a sealed box (high BL).

 

[chipperman]

Aye, there lies the rub! I talked this morning with Ezra at Worx and they don't feel the need to tune below 26hz, but even then, their box size is too large for the wife. I can go about 5 cu ft. net as I explained above. That looks like I am going to be limited to a sealed box, at least with this driver. What worries me is the rather high rolloff frequency. I have an SVS/Audyssey EQ, but it won't correct outside the native curves of the driver, requiring the use of an LT. If I could, I would like to keep this extra circuitry out of the loop. I suppose, since I am using two subs, that I might be better off using LMS Ultras in either 15" or 18" sealed, since they have better native curves down low. I doubt I'd ever go over 100db, I just want the organ pipes. What do you think of it all? It appeared that the 18" Ultra did very well. Since I've got to have two units (for symmetry, for the wife/decorator), would the 15's do it? I don't feel comfortable with the programs yet, could someone model it for me?

 

[solid7]

I would try for a passive radiator for this sub - especially if cost is no object. The box gets smaller, and PR subs have a little different sound (in my opinion/experience) which my ears prefer over traditional ported subs.

 

[Ricci]

These subs don't model very well with PR's. Not in 5 or 6 cu ft anyway.

If you want to keep the box size to 5cu ft net max for each 18" driver that basically only leaves you sealed as an option. These drivers roll off starting at around 60hz even in a box giving a Q of about 0.5so you would basically need an LT circuit or some form of EQ to bring up the low end. LMS 5400's or Ultra's would be much better suited to small sealed boxes but they are pretty much impossible to find now. The ZR/Worx drivers are going to be much better in a medium sized ported box of 7-11cu ft net than in a sealed box.

 

[chipperman]

Well, I guess I have a driver collection until I get a bigger house, or a divorce!
I wonder if 2 LMS Ultra 15's, one on each side of the room, in sealed boxes, would do the trick. I can't get the WinIsd program to work (I'll post the prolems with a separate thread) , so could anybody help me model these in a sealed box? Thanks.

 

[Ricci]

Here you go.

Red is 5 cu ft tuned to 25hz
Blue is 7 cu ft tuned to 22hz
Orange is 9.5ft tuned to 18hz
Green is 3.5ft sealed 21x21x21 external (this would be almost half the size of the 5cu ft ported system because the port adds about a cu ft)

All sims are with inductance added, 1 driver, 2000w, xmax limited output and the ported systems all have an 8" port about 38" long. Add about 6db across the board to these for the second driver recieving another 2kw. The 5ft 25hz ported would need a 20hz HPF, the 7ft 22hz tuned would need an 18hz HPF and the 9.5ft 18hz ported would need a 15hz HPF to prevent overexcursion below tune. The sealed would not need one. Electronics roll off will provide a bit below 10hz anyway and it never exceeds xmech even at 3hz with 2000w. As you can see you would need some low end boost to get deep extension sealed. With a pair of drivers you should be capable of greater than 110db from 16hz on up sealed.

FR and SPL with 2000w.

Here's cone excursion.

 

[chipperman]

Thanks. The sealed curve looks a lot friendlier, and I like the smooth roll-off. If I used a LT could I get the response flatter down lower. I x over @ 40hz, so my biggest concern is in the ultra low range.

 

[Ricci]

You would most likely need an LT and a lot of amplifier. The sealed would be much smaller. With a pair you should still have solid output and you said that you don't need insane levels anyway. I have the one LMS18 I have in a box about 4 cu ft and it is still a lot of deep bass output in a good size room. It is sort of a shame to X those at 40hz though. they have a good clean sound to them and would be much cleaner and more dynamic 40-100hz than your mains. My 2 cents.

Good luck with the build and post some pics of the drivers. Show them off. Not too many people have those.