Driver at floor level or ceiling??

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diyAudio Member
Joined 2007
In a short time we are building an extension to the house, moderately sized ( 5600 * 6600 ) and will be our main living and listening area.
There is a small possibility I may be allowed to build in a pair of subwoofers.
the only allowable possibility would be in the two opposite corners of the room and limited to a maximum of "about" 450/550mm width on the diagonal. Assuming I get permission to buy a pair of new 15 inch sub drivers
( otherwise I need to use multiple cheap 12 inch woofers with an Fs of ~30hz ) where would you optimally mount the drivers, floor, ceiling or mid point??
Ceiling is 2700mm in that corner and the planned built-in shelving will be ~330mm deep.
If building in we can add the framing to the plans now, there being a 6 month lead time on the build at the moment tho
 
Build a fake wall without her knowing ;)
Really thou, why not a simple tapped pipe, built into the false wall, would only take maybe a foot of depth off the overall size of the room, and you could make the path length as long (tall or wide) as you want to get that desired 15-20hz!
 
Build a fake wall without her knowing ;)
Really thou, why not a simple tapped pipe, built into the false wall, would only take maybe a foot of depth off the overall size of the room, and you could make the path length as long (tall or wide) as you want to get that desired 15-20hz!

Yeah, you could probably fit a pair of LMS Ultra 5400 tqwt cabinets behind a false wall and only have the mouth peek through a hole that looked like an hvac air duct ;)

I flirted with this idea myself.
 

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i was under the impression that placing a bass speaker high up in the air would reduce its low end output by doing something to its room gain?

I'd say from a purely geometrical perspective, the middle (height wise) would be the point in which that factor was the most pronounced and then reduced as you went higher to the ceiling as the ceiling would take the place of the floor as a boundary.

I've nothing to prove this though, perhaps someone has done this or has more insight.
 
diyAudio Member
Joined 2007
I guess there is the room mode to be considered as well.
Corner placement could possibly have an adverse effect.
that will be modified by 'A"the opening into the other room ( big kitchen /dining area ) tho, and "B" the fact that at this stage we look like going with a scissor trussed roof to give the maximum number of angles and "C" the fact that the woofers will be at an angle to those corners.

I did think bout the room gain corner loading which is one of the reasons for asking the initial question.

Building in is simply the cheapest option to maximise WAF, I mean 8 * 12 inch woofers ( 4 per side ) would be adequate don't you think??
 
diyAudio Member
Joined 2007
I wonder what would happen if playing a vinyl record and the caption/turntable system is a little 'resonant' .
The classic 'rumble' filter would not be adequate :rolleyes:

Well that does happen at the moment, it needs +12db on the bass and the loudness button active at the same time tho

I'll work on the turntable isolation a little more- or save "LOUD" for the digital media.
Seriously tho I do have a large number of those woofers meant for an IB installation and them we moved house
 
Mmhh ,:p , seriously !
I don't know your expectations on playing music...I guess that the monstruos bass department will be useful during some full orchestral attack , or some electronic music , or mocking the movie installations .
I feel that a 6.5 " driver it's ok for a normal room ; just made some listening and I absolutely prefer no tone controls ; someone else may prefer some loudness but it's not my cup of tea . It completely takes disregard of the content of the disc . I would like to know more of your system , Moondog.
The verb 'save' reminds me of some digital presets ....:rolleyes::(
 
diyAudio Member
Joined 2007
Well the current "System" uses an old Yamaha C-80 modified with larger better storage caps and extra heat sink on the main trannies, with the case opened out for maximum airflow.
Behringer XO
Bass amps are 300 watts
Mid amp is a Rotel 1070
Large low Qtc MTM using high Qts 8inch Tandy Midrange and a cheap silk dome tweeter.
Couple of Cerwin-Vega 124s in 19 litre sealed boxes and a Kicker 15 inch in a 155 litre sealed box ( with large first order cap bank for low boost/infrasonic filter at 18 hertz~)
XO is currently at ~120Hz
That is the current system for stereo.
Home theatre system is separate and is different again
All speaker building has been on hold while we pay for and renovate this house.

WAF is wearing a little thin on the big black boxes
 
Considering new construction and WAF, I would kind of go off that false wall theory but not quite. I'd build the back wall maybe 5.5" or 7.5" deep (2x6 or 2x8 studs) with a very solid front and back (1"? There's probably something purposeful but I'm not a construction expert). I'd then seal all the joints to essentially build in cabinets for in-wall speakers and that could handle your subs in-wall. Just big sealed spaces for the subs. Even between standard 2x4 16" studs there's over 3 cubic feet if you consider the fiberglass insulation.

Trust me, in-walls painted the same color as the wall will be much better received than ANY box. And if the wall is well built, in-walls can sound BETTER than boxes due to eliminating an entire set of early reflections.

Just say "you know, I'm just going to build it all into the wall" and discuss the wall with the contractor when she's not around.

Don't do any weird corner pieces. Seen that done-it just looks weird, it will NOT look "built in." "Built in" means firing through a grille from the ceiling or wall or floor.

And, remember all woofers die eventually. Be sure to make something modular you can change later on.
 
If it's an 8' tall room, that's 7.5' top to bottom depending on exact construction. With 16" studs that 14.5" = 1.2' between. Standard wall depth of 3.5" =0.3' (2x6: 5.5"=0.46'; 2x8: 7.5"=0.63'; 2x12: 11.5"=0.96)

So the typical wall is 7.5x1.2=9 square feet.
2x4=2.7 cubic feet, unstuffed.
2x6=4.1
2x8=5.7
2x12=8.6
Your results will differ since Australia is sensibly metric. But the point is you could go less than 300 mm if that is somehow a problem.

At 300mm, I'd be thinking to try and build in some kind of vertical horn array or something. I have a "someday" dream where a floor-to-ceiling array of drivers feeds into a spiraled horn, which opens into the room, emitting a floor-to-ceiling plane wave.
 
If it's an 8' tall room, that's 7.5' top to bottom depending on exact construction. With 16" studs that 14.5" = 1.2' between. Standard wall depth of 3.5" =0.3' (2x6: 5.5"=0.46'; 2x8: 7.5"=0.63'; 2x12: 11.5"=0.96)

So the typical wall is 7.5x1.2=9 square feet.
2x4=2.7 cubic feet, unstuffed.
2x6=4.1
2x8=5.7
2x12=8.6
Your results will differ since Australia is sensibly metric. But the point is you could go less than 300 mm if that is somehow a problem.

At 300mm, I'd be thinking to try and build in some kind of vertical horn array or something. I have a "someday" dream where a floor-to-ceiling array of drivers feeds into a spiraled horn, which opens into the room, emitting a floor-to-ceiling plane wave.

Hi,

The somewhat expensive approach: Use a JL Audio 13TW5-3 driver in a ~96L T-TQWT...f-3dB=~20 Hz-80Hz

JL Audio 13TW5-3 Component Car Subwoofers at Onlinecarstereo.com

b:)
 

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You probably know this, but if at all possible make the room dimensions to avoid room mode overlap. If your making that wall with staggered studs to provide noise isolation (from your music into another room, not for external noise into your music) putting speakers in the wall is a bad idea.
 
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As far as placement,every boundary doubles the output (in theory, in practise it depends on the boundary) So a corner gives a gain of 8 times. The catch is higher freq will comb filter because you always have some distance between the wall and the driver. Thats why people soffit mount. (inwall). If i where you i would mount the subs in the wall (in a proper box) behind your main speakers a couple of feet up the wall. You wuold barely see them.
 
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