What do I do with 4 CSS Trio 12s? - AVS Forum
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post #1 of 16 Old 08-23-2012, 08:54 AM - Thread Starter
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Hey all,

I just moved and have 4 CSS Trio 12s. I'm starting fresh since I just moved. I'm not sure what I want to do with these yet. They seem better suited for 19hz ported design than anything, but I'm thinking a pair of dual opposed.

Space is somewhat a concern, but not the end all. I'm more interested in sound quality (aka flat response) than anything. So spread out multiples would be good. The extention of a sealed design is appealing, but not the end all either.

What should I do? I'll build a couple test boxes and am prepared to rebuild if it doesn't work. And I can test outdoors and indoors. But would like to at least start in a reasonable direction.

Thanks.
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post #2 of 16 Old 08-23-2012, 07:53 PM
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what kind of room are you working with?

Listen. It's All Good.
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post #3 of 16 Old 08-24-2012, 06:57 AM - Thread Starter
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An! Of course. Knew I was missing something.

It's a walkout basement with a concrete slab, but wood framed walls. It's narrow and long. I'll get some dimensions. Opens up to all of the house via hallway and stairwell.

I also have a minidsp to handle any processing as required.
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post #4 of 16 Old 08-24-2012, 07:08 AM - Thread Starter
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It's 11.5 x about 30, with an 8' ceiling. The rear of the room has the stair well. I'm hoping the length makes for a good damper. We will likely sit about mid way though.
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post #5 of 16 Old 08-24-2012, 07:40 AM
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I wish I had an empty room to design a system for!

That long room could be a challenge. Fire the subs down the long dimension and you will likely excite some nasty low frequency standing waves. I had a sub facing a kitchen wall 30' feet away and had a sharp 1o db peack at about 17 hz a corresponding deep null at 34 hz.... So placement will make a big dffirence. That is probably the first question to answer.

If the corners are empty and usable. I would try them first for the free gain but that supposedly excites all the modes in the room. Nevertheless, you have 4 drivers and so could make 4 subs with 2 in the corners and two somewhere else to fill in the nulls.
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post #6 of 16 Old 08-24-2012, 08:11 AM - Thread Starter
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Quote:
Originally Posted by JackNC View Post

Nevertheless, you have 4 drivers and so could make 4 subs with 2 in the corners and two somewhere else to fill in the nulls.

Ya, so maybe I shouldn't go dual opposed. 4 separate 75L sealed cabs may be best. Then I can try stacking and spreading.

If I get a peak at 17hz, then I don't really need the ported. I do wonder how bad the length of the room will be though. With the stairway and it open to another room. It's not a dead end if you know what I mean.
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post #7 of 16 Old 08-24-2012, 08:57 AM
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only one way to find out...

the peak at 17 hz isn't the problem except if/when you test with a 17 hz sinewave. Its not noticeable with normal program material . For me anyway, the null in the 30's was (and is) more of an issue. I still haven't got multisubs set up. BTW I'm using two dual opposed epic 10s as stands for my mains in a very open room. they are enough for me and more than enough for my wife, if you know what I mean:)

If you sim the CSS sealed, you'll see you need only 12db or so of linkwitz transform to equalize it flat to 20 hz. You will also get boundary gain with your basement walls and floor so with 4 drivers you likely have enough SPL. Simulate vented and you will see you start getting into pretty large box sizes to tune to 20 hz with a reasonable vent.

Jack
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post #8 of 16 Old 08-24-2012, 09:56 AM - Thread Starter
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Ya, I'm not going for reference SPL. If I miss the mark by 3db or even 6db... more than enough for me and my wife as well wink.gif

Maybe I'll go with a dual opposed in one of the front corners. Then two singles I can move around and flatten the response.

I agree that a null in the 30s would be very frustrating. So much content right there. I could move the singles around to smooth that out possibly.

Sealed volume is my next thing then. I'm with you on the ported. Although the massive gains are tempting, I don't think it's worth it. But should I build 60L cubes, or bigger lower q cubes. I'm not seeing much advantage with the larger boxes in unibox. I think I'll keep them small. Thoughts on that? Of course I'll make the dual opposed cab twice the volume.
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post #9 of 16 Old 08-24-2012, 01:32 PM
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60L is about as big as you can go without needing a high pass to protect from over excursion. That is where I would draw the line also. Dual opposed would be just over 4 cu.ft. That's not exactly small but its not too bad: 17" x17" x 24" (internal dimensions).
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post #10 of 16 Old 08-24-2012, 08:40 PM - Thread Starter
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I can handle that size no problem. I'll do a dual opposed and two downfiring cubes. I'm feeling pretty good about that. Only thing I may rebuild is the dual opposed is it's better orientated vertically. I'll start horizontal though.
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post #11 of 16 Old 08-25-2012, 04:03 AM
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Vertical vs horizontal is an interesting question. If you go vertical and tall enough, then you have one driver up high to help combat floor and ceiling reflections. If you go horizontal and place it off center on the wal, then the two drivers each at different distances from each side wall help combat side wall nulls. Geddes I think recommends one woofer up high and Bosso builds a stack of dual opposed in one corner.

Sure you don't want to get a couple more of those TRIOs smile.gif
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post #12 of 16 Old 08-25-2012, 04:04 AM
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Vertical vs horizontal is an interesting question. If you go vertical and tall enough, then you have one driver up high to help combat floor and ceiling reflections. If you go horizontal and place it off center on the wall, then the two drivers each at different distances from each side wall help combat side wall nulls. Geddes I think recommends one woofer up high and Bosso builds a stack of dual opposed in one corner.

Sure you don't want to get a couple more of those TRIOs? smile.gif
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post #13 of 16 Old 08-25-2012, 04:05 AM
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Vertical vs horizontal is an interesting question. If you go vertical and tall enough, then you have one driver up high to help combat floor and ceiling reflections. If you go horizontal and place it off center on the wal, then the two drivers each at different distances from each side wall help combat side wall nulls. Either Geddes I think recommends one woofer up high and Bosso builds a stack of dual opposed in one corner.

Sure you don't want to get a couple more of those TRIOs? smile.gif
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post #14 of 16 Old 08-25-2012, 09:53 AM - Thread Starter
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Quote:
Originally Posted by JackNC View Post

Sure you don't want to get a couple more of those TRIOs? smile.gif

Oh I sure would. I think I'll add a pair of 15" sdx down the road biggrin.gif

I think maybe I'll go straight to a Bosso copy and do it vertically. That'll better match the two downfiring singles and tackle the ceiling reflection. Good call. Thanks.

Now I'll go buy some wood smile.gif
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post #15 of 16 Old 09-16-2012, 01:14 AM
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I don't understand people's concern with over excursion. I'm assuming of course that most people are using CD as their prime music source and the low frequency limit is 20 Hz. With Home Theater I believe it is still the same range 20 Hz to 20 KHz. The only way you might run into over excursion is if you are playing LP's and then the inherent flaws from disk warp and tonearm feed back can indeed be a problem. Is there some other problem I'm unaware of where over excursion might happen? Haven't paid any attention to the HT end of things so would love to be informed if there's more things to be concerned with than I knew about.
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post #16 of 16 Old 09-16-2012, 02:01 AM
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Sorry Spydie old pal, you need to come up to speed on HT. LFE channel is 3Hz to 120Hz (lower depending on xover setting) and on lots of discs there is a lot of very deep, very loud ULF. For every octave lower you go, you need 4x the volume displacement to get the same SPL.

Read this thread.

I agree with your LP disc warp comment, and am adjusting my system so it will roll off quickly below 20Hz when LP is the source.
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