Quad 18 in-floor Infinite Baffle Subwoofer - AVS Forum
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post #1 of 51 Old 04-23-2012, 08:10 PM - Thread Starter
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Just finished building this project and tested it out full-bore today.

Listening Impressions:
-There is no need for tactile tranducers with this setup. The floor literally ripples, bouncing the couch upon it like a small toy.

-It sounds nothing like any other subwoofer I've ever heard. The sound is so clean and uncolored that it is... transparent. To be honest, I thought something was missing at first. It turns out, something is missing... all the extra distortion every other sub I've ever heard made. Now I can hear every part of a sweet bass line. The veil has been lifted.

Parts:
-4 Ficar IB3 18" drivers
-2 manifolds (2 drivers each) placed for smoothest in-room response
-1 Crown XLS5000 amp sending about 1000 watts @ 8ohms to each manifold.
-EQ'ed with Audyssey XT32 dual sub equalization (Denon 4311ci)
-Room is 1600cf, sealed. (13'x15'x8')

In-room appearance:

Basement view:


One thing I personally like about this type of subwoofer install, is that it doesn't require much finish work or getting the box/port size right.. because none of that matters much.
The fact there are no more giant boxes and wires in the room is nice also. Especially from a pet and child-proofing point of view.

I'm sure I'll get out REW again and eventually post the typical cool plots of flat response below 10hz.
Right now, though, I'm too busy listening.

Couldn't have made this without all the great ideas I got from all the smart people here over the years.
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post #2 of 51 Old 04-24-2012, 10:41 AM
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Awesome job! I am sure you are psyched with this setup. I will be following, as I am getting ready to start my IB build as well. How big is the mouth for each manifold on yours??
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post #3 of 51 Old 04-24-2012, 11:15 AM - Thread Starter
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I used 14"x20" grates. They fit between the floor joists. You can find any size grate you want online. Generic ones like I have cost about $30 each.

I wasn't planning on posting a lot more build details on this thread, but I guess I'll throw up a few things. Maybe someone will see this and say "what the heck is an infinite baffle subwoofer??!!?" and start doing some research, as I did years ago.
Lookup "The Cult of the Infinitely Baffled" for more information.

I think its a great option for those who have the space for it. Arguably the ultimate subwoofer type.
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post #4 of 51 Old 04-24-2012, 11:17 AM
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I'm not sure how the manifold does not act like a T-Line, I would think you would need to tune it like a port (and likely have it much longer, perhaps to the floor of the basement.)
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post #5 of 51 Old 04-24-2012, 11:32 AM - Thread Starter
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Quote:
Originally Posted by mcsoul View Post

I'm not sure how the manifold does not act like a T-Line, I would think you would need to tune it like a port (and likely have it much longer, perhaps to the floor of the basement.)

I don't know, I just followed what others have done. They have been building subwoofers this way for over 15 years with no issues. I'm told these act like a giant compression driver, not a transmission line, whatever that means.

One of the big reasons I built this type of subwoofer is that you don't need to worry about things like port tuning. Just make a box big enough to fit the drivers, clamp it to the floor joists, and go. It's really that simple.

Some people have made these with *tiny* manifold openings (like a 4"x10" slot) and had a small reduction in response over 70hz, but that's an extreme situation.
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post #6 of 51 Old 04-24-2012, 11:59 AM
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S_rangeBrew

As before, congrats. Thanks for sharing.


Quote:
Originally Posted by mcsoul View Post

I'm not sure how the manifold does not act like a T-Line, I would think you would need to tune it like a port (and likely have it much longer, perhaps to the floor of the basement.)

No T-Line. I like to think it's more akin to a co-entrant, compression system. With regard to the length, the shorter the better. But solid results have been achieved even with long, multi-driver manifold IB's.

Such as these two from The Cult.;







S_rangeBrew, btw,...I really like the way those HVAC registers/grates worked out. Nice, stealthy, finished appearance.


Thanks
LL
LL

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(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
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post #7 of 51 Old 04-24-2012, 04:30 PM - Thread Starter
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Quote:
Originally Posted by FOH View Post


S_rangeBrew, btw,...I really like the way those HVAC registers/grates worked out. Nice, stealthy, finished appearance.

I can't wait to demo an intense LFE scene with someone who doesn't know about these and thinks they are just air vents. Should be... funny.

As a childish experiment, I put a piece of paper over one of the grills and then played the Cloverfield scene. Pretty funny watching it levitate and ripple.

Thanks for the input, alway enjoy seeing various DIY projects.
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post #8 of 51 Old 04-24-2012, 04:41 PM
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Sweet looking build!!! Can you please post some more pics of the enclosure itself? Also more pics of where the grate is located in the room with reference to your couch...???


Thanks,
dbl

Let's all go to the lobby
....Let's all go to the lobby
........Let's all go to the lobby
............To get ourselves a treat!
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post #9 of 51 Old 04-24-2012, 04:47 PM
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Quote:
Originally Posted by S_rangeBrew View Post

I don't know, I just followed what others have done. They have been building subwoofers this way for over 15 years with no issues. I'm told these act like a giant compression driver, not a transmission line, whatever that means.

One of the big reasons I built this type of subwoofer is that you don't need to worry about things like port tuning. Just make a box big enough to fit the drivers, clamp it to the floor joists, and go. It's really that simple.

Some people have made these with *tiny* manifold openings (like a 4"x10" slot) and had a small reduction in response over 70hz, but that's an extreme situation.

Quote:
Originally Posted by FOH View Post

S_rangeBrew


No T-Line. I like to think it's more akin to a co-entrant, compression system. With regard to the length, the shorter the better. But solid results have been achieved even with long, multi-driver manifold IB's.

Such as these two from The Cult.;


S_rangeBrew, btw,...I really like the way those HVAC registers/grates worked out. Nice, stealthy, finished appearance.


Thanks

Very cool! thanks for sharing the knowledge. Looks like I was making connections with other builds I have seen that do not exist.

This IB manifold thing is neat.
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post #10 of 51 Old 04-24-2012, 05:21 PM
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Nice job. Measurements!!
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post #11 of 51 Old 05-04-2012, 01:33 PM - Thread Starter
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Ok, after "breaking" these in for a few weeks, I decided to see how far I could push them.

I broke out all the "Sub-Killer" content I know about:

War of the Worlds
Bass I love u
Cloverfield
THX Amazing Life
...and a bunch more.

I played all of these at reference and sometimes a little above. This is probably at least 5 to 15 decibels higher than I would ever listen to anything in "real life". I'm hoping that with some more room treatments, this will be improved, as I really enjoyed the LFE effects at these high levels. (Turning the subwoofer channels up alone unbalances things, so I'm going to work on taming the highs)

Results: These subwoofers just laugh at any attempt to bottom them out. During War of the Worlds and Cloverfield, giant monsters are not only on the screen, they are under my home theater, punching the floor. The couch Is literally jumping up and down with the floor flexing. The "bass mushrooms" from the THX demo do their best to blow the windows out of the walls! But if you go down into the basement where the backwave is, there is really no drama except for a couple of loose paint cans rattling. The manifolds with their opposed drivers are vibration-free. The driver cones are using quite a bit of excursion, but making no noise, clicks or clacks. The clip lights on the amp are not even flickering.

I can only assume the room gain in this 1600cu.ft sealed room is quite large, and as a result, these things have plenty of overhead.

Yes, it's true, you can't really HEAR content below 20hz.... but anyone who says it is worthless has never felt the gut-wrenching physical POWER and MOVEMENT this content provides. Bass shakers and Buttkickers would be absolutely redundant in my system.

I have reached bass nirvana. Aside from adding a rotary subwoofer, it would be impossible for me to get better subwoofer in this room. Fin. Done. Perfection accomplished. Subwoofer upgraditis is no more.
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post #12 of 51 Old 05-04-2012, 03:51 PM
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Quote:
Originally Posted by S_rangeBrew View Post

I have reached bass nirvana. Aside from adding a rotary subwoofer, it would be impossible for me to get better subwoofer in this room. Fin. Done. Perfection accomplished. Subwoofer upgraditis is no more.

Congrats man. I always like hearing that someone has satisfied their LFE itch. I would love to hear a system like yours and a system like notnyt's one after the other just to compare the differences.

I have never heard an IB setup so it would be an interesting comparison. Plus I just want to see if I could survive not's at full volume...

 

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post #13 of 51 Old 05-05-2012, 06:17 AM
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Here's a pic of my buddies IB, no hipass, minimal EQ. Are you using any EQ before Audyssey...

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post #14 of 51 Old 05-05-2012, 08:45 AM
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Thats a very nice setup. I love the "no box" look. Starting on a quad IB setup myself using 4 RE xxx 18's. i have learned very much from thecultoftheinfinitelybaffled.
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post #15 of 51 Old 05-05-2012, 11:12 AM
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Quote:
Originally Posted by kgveteran View Post

Here's a pic of my buddies IB, no hipass, minimal EQ. Are you using any EQ before Audyssey...



I wonder if you could run 2 theaters off the same subs like that? Not that it would be a good idea, but one theater above and one below with an A/B switcher for the subwoofer amp/s.
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post #16 of 51 Old 05-05-2012, 12:13 PM
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Quote:
Originally Posted by mcsoul View Post

I wonder if you could run 2 theaters off the same subs like that? Not that it would be a good idea, but one theater above and one below with an A/B switcher for the subwoofer amp/s.

Yep, it's been done.

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------------------------------------
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(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
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post #17 of 51 Old 05-05-2012, 01:21 PM - Thread Starter
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Quote:
Originally Posted by popalock View Post

Congrats man. I always like hearing that someone has satisfied their LFE itch. I would love to hear a system like yours and a system like notnyt's one after the other just to compare the differences.

I have never heard an IB setup so it would be an interesting comparison. Plus I just want to see if I could survive not's at full volume...

First, I very much doubt you or the house would survive notnyt's at full volume. d

Both systems would have plenty of overhead, so the differences would be in the room response, EQ and any inherent differences between IB and what notnyt is using. There are two schools of thought... one says IB's sound so clean because of their design, and another says they sound so clean because of the amount of drivers they use, and the resultant low distortion. After using one, I'm SOLIDLY in the first camp. I predict you would hear a huge difference in sound because of the sealed vs. IB designs.
As to which one you would like, who knows? There are people who dislike the IB sound.
I also think one large positive of having a IB in the floor as I do is that the rear wave and front wave combine to flex the floor like a giant diaphram, which is a great effect worth pursuing, IMHO.

Quote:
Originally Posted by kgveteran View Post

Here's a pic of my buddies IB, no hipass, minimal EQ. Are you using any EQ before Audyssey...

Looks just like my setup. I'm also using no highpass, and feeding these drivers with about 2X the safe power they can handle, but as I've said before, I've found no content with threatens them.
I'm not using any EQ except for XT32.

Quote:
Originally Posted by keager View Post

Thats a very nice setup. I love the "no box" look. Starting on a quad IB setup myself using 4 RE xxx 18's. i have learned very much from thecultoftheinfinitelybaffled.

Hope you find a good place to install those BEASTS. Probably the most impressive drivers I've ever seen, and that includes the LMS Ultra.
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post #18 of 51 Old 05-05-2012, 03:02 PM
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Well the good and bad part about under my house is that there is only about 22 inches of crawlspace. Good because the manifold and drivers can also be supported to the ground, bad because its gonna be a pain to install them in such cramped conditions with them weighing 78 lbs each. Where there's a will, there's a way though....
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post #19 of 51 Old 05-05-2012, 04:15 PM
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Really glad you're enjoying your set-up. Perma-grin,... I'm sure

Quote:
Originally Posted by S_rangeBrew View Post

Looks just like my setup. I'm also using no highpass, and feeding these drivers with about 2X the safe power they can handle, but as I've said before, I've found no content with threatens them.
I'm not using any EQ except for XT32.

By any chance, did you free air test them prior to install?

------------------------------------
Flat, Deep, Clean, Linear, and Loud
------------------------------------
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB
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post #20 of 51 Old 05-05-2012, 05:50 PM
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Quote:
Originally Posted by keager View Post

Well the good and bad part about under my house is that there is only about 22 inches of crawlspace. Good because the manifold and drivers can also be supported to the ground, bad because its gonna be a pain to install them in such cramped conditions with them weighing 78 lbs each. Where there's a will, there's a way though....

So you are going ahead with it? Should be awesome when finished. Good luck with the install.
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post #21 of 51 Old 05-05-2012, 05:54 PM
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Thanks ricci, I figured out a way to get the driver to where I need them without disassembling them. You were right, that would have been like blindfolded brain surgery reassembling them under there. S_rangebrew, where did you order your registers?
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post #22 of 51 Old 05-06-2012, 11:04 AM
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Quote:
Originally Posted by keager View Post

Well the good and bad part about under my house is that there is only about 22 inches of crawlspace. Good because the manifold and drivers can also be supported to the ground, bad because its gonna be a pain to install them in such cramped conditions with them weighing 78 lbs each. Where there's a will, there's a way though....

I thought the RE XXX 18's weigh closer to 110lbs per driver? Regardless, 78lbs or 110lbs+... It would be rough to handle in that crawlspace. Bet it would sound killer.

 

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post #23 of 51 Old 05-06-2012, 11:25 AM
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They are 113 lbs in their insane box they come in. I'll start a build thead soon when I get plans solidified.
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post #24 of 51 Old 05-07-2012, 04:50 PM - Thread Starter
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Quote:
Originally Posted by FOH View Post

Really glad you're enjoying your set-up. Perma-grin,... I'm sure



By any chance, did you free air test them prior to install?

There is a procedure for this? What does it measure? I've seen a few videos of it being done, but I must have missed the reasoning. Most of the videos are just kids doing it with car subs because it looks "cool". I don't think that's what you're talking about.

Someone on here said it would be a good test for IB subwoofers, but I never found out how to do this test.
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post #25 of 51 Old 05-07-2012, 05:02 PM - Thread Starter
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Quote:
Originally Posted by keager View Post

Thanks ricci, I figured out a way to get the driver to where I need them without disassembling them. You were right, that would have been like blindfolded brain surgery reassembling them under there. S_rangebrew, where did you order your registers?

Atlanta Supply Company

The 1530B model is the one I got. It's just a simple grate with no dampers. It is available in almost any size and is cheap. It's also meant to be walked on, so it's very strong. It's design means almost no air resistance. I countersunk it into the carpet by removing the carpet padding around the edges of the hole I cut in the floor. Vacuum cleaners and children run right over them with no worries or damage.

BTW, did you ever calculate the displacement of those drivers you are using? They may be an option for those who need 8 FiCar IB3's worth of displacement, but only have room for 4 18" drivers.... if they move a lot more air. (FiCar IB3 18's move around 7 liters each)
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post #26 of 51 Old 05-07-2012, 05:51 PM
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Quote:
Originally Posted by S_rangeBrew View Post


Atlanta Supply Company

The 1530B model is the one I got. It's just a simple grate with no dampers. It is available in almost any size and is cheap. It's also meant to be walked on, so it's very strong. It's design means almost no air resistance. I countersunk it into the carpet by removing the carpet padding around the edges of the hole I cut in the floor. Vacuum cleaners and children run right over them with no worries or damage.

BTW, did you ever calculate the displacement of those drivers you are using? They may be an option for those who need 8 FiCar IB3's worth of displacement, but only have room for 4 18" drivers.... if they move a lot more air. (FiCar IB3 18's move around 7 liters each)

Have not calculated the dispacement. 54 mm xmax. I'm surprised nobody has used them for IB. Well I guess cuz they are expensive and incredibly heavy. Going to run all four off my lab clone.
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post #27 of 51 Old 05-07-2012, 06:57 PM
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iirc, jeremy clarkson (top gear) had this to say about i.b. subs:

"if you have never heard of an infinite baffle subwoofer, you wouldn't be alone.

and to be honest, just looking at a hole in the floor doesn't do much to inspire confidence.

however, once the bass starts, that all changes...

just imagine sticking your head "inside" the biggest, baddest, subwoofer that you can you can possibly imagine,
and then turning the volume...all the way up.

this isn't just bass. this is getting body slammed by a 400 pound sumo wrestler...and i do love it.

wwhhooaahhhh........yyyyeeeaaahhhh........"

;-)

Listen. It's All Good.
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post #28 of 51 Old 05-07-2012, 07:50 PM
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Can't wait!
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post #29 of 51 Old 05-08-2012, 11:02 AM
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Quote:
Originally Posted by S_rangeBrew View Post

There is a procedure for this? What does it measure? I've seen a few videos of it being done, but I must have missed the reasoning. Most of the videos are just kids doing it with car subs because it looks "cool". I don't think that's what you're talking about.

Someone on here said it would be a good test for IB subwoofers, but I never found out how to do this test.

Upon receiving any drivers, especially subwoofers, I like to test them with some signal prior to installation.

With IB drivers, and the manner in which they're excursion limited instead of thermally limited, it's important to know precisely where the limits exist,...especially within the gain structure you plan to implement. To discover this, you've got to ease the power to them, little by little until; a.)your amp runs out of power, or b.)your driver encounters it's excursion limits. With a frequency generator, like the various PC based tone generators available, one can explore power handling and excursion at different frequencies as well.

Well, if you were to install the driver, and then pursue these tests, you'd have to endure untold stress on your valuable hearing. This is where the free air element of this comes into play. In free air, the drivers acoustically null a significant amount of the potential energy,...thus easy on the ears. This way, with ample power you can easily hear when the driver begins to encounter the physical limit (VC former into the back plate, in the case of the IB3-18's).

By observing the clip lights, monitoring each gain stage position, EQ, etc, you can get a good feel for the overload characteristics of each element in the system,...make notes, etc, and proceed accordingly.

Each driver from each mfr enters into it's limitations in different ways. Other enthusiasts may or may not agree, however I've found its quite helpful not only for the reasons I stated above, but also for my own quality control that each drive unit operates similarly as it's exposed to equal amounts of drive voltage.

You can re-configure the load by paralleling, series, series-parallel, and bridging the amplifier. By doing this you can explore each combination of load impedance, and subsequent power output from your amplifier.


I hope this answers your question.


All the best

------------------------------------
Flat, Deep, Clean, Linear, and Loud
------------------------------------
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB
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post #30 of 51 Old 05-08-2012, 05:03 PM
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Quote:
Originally Posted by LTD02 View Post

iirc, jeremy clarkson (top gear) had this to say about i.b. subs:

"if you have never heard of an infinite baffle subwoofer, you wouldn't be alone.

and to be honest, just looking at a hole in the floor doesn't do much to inspire confidence.

however, once the bass starts, that all changes...

just imagine sticking your head "inside" the biggest, baddest, subwoofer that you can you can possibly imagine,
and then turning the volume...all the way up.

this isn't just bass. this is getting body slammed by a 400 pound sumo wrestler...and i do love it.

wwhhooaahhhh........yyyyeeeaaahhhh........"

;-)

Clarkson is awesome... I'm going to need a reference for that quote though.

 

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