Building big, with small footprint. Would like some help and feedback. - Home Theater Forum and Systems - HomeTheaterShack.com
 
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post #1 of 9 Old 03-04-12, 01:14 PM Thread Starter
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Building big, with small footprint. Would like some help and feedback.

Hi

Im planing to build a subwoofer system with a small footprint, but theirs so many designs and options to choose from. It got me somewhat confused :S What i want from the system is high SQ, ability to play the entire LFE(120Hz to 10ish Hz) with confidence, and the ability to play at HIGH SPL! even down to the 10's.

The setup i boiled it all down to(for now) is two 18" subwoofers with four 18" p-r's in a column/array type design.
Actually i'm planing to build two subwoofers like this, and running them in stereo when i play music.

The information i couldn't find is how narrow and shallow i could build the cabinet without sacrificing SQ. Can i build it so it just barely fits the 18"'s? Or would it be a better choice to build this with 15" or even 12" woofers and p-r's instead?

Other designs i have looked into is sealed(like stacking four SB13-U on top of each other) and dual opposed(like stacking Submersives), i hope you understand the examples i trying to make here:P

Is there some benefit with going dual opposed or sealed vs p-r's?

The components i been looking at so far is TC Sound PRO 5100, Ultra and LMS-R with VMP's. But i'm also considering Precision Devises, Elemental Designs and so on. The amp i plan to drive this with is Crown I-Tech 6000's, but i could consider going for Behringer iNuke's if they turn out to be good, just to save me some cash.

EDIT: My plan was to have the woofers firing from the front and the p-r's firing from the sides. As i would like to place it close to the wall.

Is there some other suitable design i have overlooked?
And help would be appreciated greatly!

Regards
Truls =)

Last edited by Truls; 03-04-12 at 01:34 PM.
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post #2 of 9 Old 03-04-12, 11:03 PM
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Re: Building big, with small footprint. Would like some help and feedback.

I am not sure what type of SPL you are wanting but dual 18's would be the minimum for me and high spl down to 10hz.

What cabinet size are you working with?

Dual 15's would be possibly louder than dual 18's.

Depth will be a matter of what you can allow and fit the driver. Make sure you have a big enough base to support your subwoofer also.

Dont forget also about the RE XXX 18". That subwoofer is a beast but excels down low also. It is cheaper than the LMS Ultra but thats up to you. And it likes sealed cabs with lots of power.

What do you have now for subs?

5100 will be good for up high but not as good down low like the Ultra.

"Music is the space between the notes"
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post #3 of 9 Old 03-05-12, 05:22 AM Thread Starter
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Re: Building big, with small footprint. Would like some help and feedback.

The sizing isn't determined yet, but i have the height of the room to work with to give the cabinets the required volume. Room height is around 7.55'. Just to make an example that would be 1.66x1.66x7.55 outer dimension, that would give me approximate 13.5cf to work with. But then i haven't calculated in the bracing, drivers and so on, only the inner volume.

What i have now is two Elemental Designs A7s-650's.

What benefits would the RE XXX have over the TC Sound drivers?
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post #4 of 9 Old 03-05-12, 06:48 AM
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Re: Building big, with small footprint. Would like some help and feedback.

Efficiency down low.

So 20" x 20" x 7.5ft. Wow....big box. For the most part a pair of port LMS Utra's would be killer and hard to beat down low. The RE XXX's like sealed cabs so the Ultra would have more SPL down low.

But always remember just build a simple cabinet ported or sealed and just add more cabs to your desire. When wanting BIG SPL at 20hz it will be easy with a pair of 18's but when wanting big SPL and 10hz you need more displacement like four 18's or more.

I am apart of the HUGE SPL type with low distortion so I like lots of displacement. SO with the money you would like to spend I would just get four 15's per side and be happy. HUGE SPL and low distortion. Make the cabinets dual opposed sealed and your ROCK'n.

Now if wanting to just go with single drivers the TC SOunds are some of the very best low distorion subwoofers out there.

SO what subs are you used to already? Curious how much SPL are you after?

I never knew how much SPL I wanted until I heard a few subs and built quite a few then I established what I wanted SPL wise. The only reason I am going to have so much displacement is because I want low distortion and the subs to be at ease when going to single digits.

That being said, I must say again, that a pair of Ultra 18's in sealed or ported will be very powerful and 95% of people out there wont want more.

How big is your room?

"Music is the space between the notes"
[T]o talk well and eloquently is a very great art, but that an equally great one is to know the right moment to stop.
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post #5 of 9 Old 03-05-12, 07:01 AM
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Re: Building big, with small footprint. Would like some help and feedback.

It would also be nice if Stereo Integrity could get their 15's out then you could use 8 of those dual opposed sealed 2 or four cabinet stacked in two locations and that would be LOUD. As in "I think my room is going to fall apart and the woofers are barely moving," loud.

Its all just a matter of what do you want to do or start with.

"Music is the space between the notes"
[T]o talk well and eloquently is a very great art, but that an equally great one is to know the right moment to stop.
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post #6 of 9 Old 03-05-12, 07:29 AM
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Re: Building big, with small footprint. Would like some help and feedback.

Just curious why you want high SPL down to 10 hz? In most movies there isn't much happening below 15 hz.




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post #7 of 9 Old 03-05-12, 09:28 AM Thread Starter
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Re: Building big, with small footprint. Would like some help and feedback.

Thanks for the reply guys!

@chrapladm: 20"x20"x7.5' is the absolute max i have to use, would like it to have a smaller footprint if that is doable. The plan was to have two of these, one placed by each front speaker so i could run them in stereo when listening to music.

Originally i was thinking of four Ultras/5100 and eight 18 VMP's(two subs and four VMP's on each side). But for the same price i could get twelve LMS-R/Axis 15"s and run six dual opposed sealed subs . with that setup i would get away with a small footprint, like 19"x19" inches, and it would be more versatile/easy to move and so on.

My room is approx 2080cf(i use metric units so i'm not 100% on this). The subwoofers i'm used to is sealed subs, but that shouldn't be the main criteria at all.

But what would give me most bang for the buck regarding SQ, SPL and amplifier-requirements? And i like your idea of building a pair of subs, and just build some identical subs and stack them if i want more, that way i could save money if i find just a pair of them enough.

So now i'm thinking Sealed dual opposed vs p-r setup, advantages and disadvantages.

@Mike P. : To be future-proof, to be sure i don't miss out on something, to avoid thinking "what if". Like all men, i like to drive a sports car even tho there's a speed limit.

Last edited by Truls; 03-05-12 at 09:45 AM.
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post #8 of 9 Old 03-13-12, 12:39 AM Thread Starter
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Re: Building big, with small footprint. Would like some help and feedback.

I have started the process of simulating different drivers on different enclosures. And it turns out that the LMS-R 15"and the AXIS 15" both need a wery large box to get a desirable low Q. So i started modeling some of the other TC Sounds drivers, and to my surprise, the LMS-Ultra has a displacement almost equal that of two LMS-R 15"s and it can use a much smaller box to get to the same Q!

So how low Q is low enough? As i understand it its good to have it under 0.707 for a SQ oriented system? And under 0.577 to get it rely thigh and defined?

And also, is it important what way i orient the woofers? can subwoofers fire from the front corners and towards the center without leveling each other out?

The idea of building/buying the wrong setup sends shivers down my spine!

Last edited by Truls; 03-13-12 at 12:45 AM.
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post #9 of 9 Old 03-13-12, 02:45 AM
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Re: Building big, with small footprint. Would like some help and feedback.

Everyone has a different opinion on which Q to go for. Some say .5 is great and some like higher. From all my journeys through reading I use Q as a good guideline for system alignment but you can use either .5-.8 and be fine after EQ.

My subwoofers like big boxes so my simple 6.5cuft cabinets will yield around a .83Q. Which for me allows greater protection for the driver in my system without the need for a hpass. And in some stuffing and EQ and we have achieved a lower Q but still have better mechanical protection because of using the higher Q cabinet.

Hope this makes sense. There are lot of different opinions on this also that differ from mine.

Subwoofer placement is a game you have to try and see which yield the best results. Everyone is different so what works for me might not work for you.

"Music is the space between the notes"
[T]o talk well and eloquently is a very great art, but that an equally great one is to know the right moment to stop.
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