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Sub-woofer placement
#159180 02/19/07 07:24 PM
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I've been reading Clint DeBoer's review of the Epic 80 system on audioholics.com and he talked about "crawling around on all fours" to locate the sweet spot for the sub. What does this entail? And is it really that hard to place a sub-woofer? I know room geometry matters, but I have a 12x22x8 room and I'm looking at buying the 350.Thans Mark


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Re: Sub-woofer placement
agentfox1942 #159181 02/19/07 07:49 PM
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getting to 2,000 posts; one year at a time vp160/qs8/qs4/ep350/m60/m2200s
Re: Sub-woofer placement
agentfox1942 #159182 02/19/07 08:58 PM
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Welcome Mark.

As you guessed, the room dimensions should not be evenly divisible. I see that you are 12x22x8. That could pose some problems, and you most likely will have to do some acoustical treatments.


Shawn

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Re: Sub-woofer placement
real80sman #159183 02/19/07 09:12 PM
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I read the article (I should have looked there first) and it does answer my questions. Thanks for pointing me there. I'm confused about the dimensions not being evenly devisable?? Is this a "rule-of-thumb" or some hidden mystical code held closely between audiophiles like the secrets of the mason's?


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Re: Sub-woofer placement
agentfox1942 #159184 02/19/07 10:14 PM
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12ft x 12ft x 12ft is not good

24ft x 12ft x 6ft is not good

22ft x 12ft x 8ft YOUR room, I don't think you will have to many problems, unless you have bare walls.


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Re: Sub-woofer placement
agentfox1942 #159185 02/19/07 10:35 PM
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Normally, we don't give this info out until you've been officially indoctrinated into the society, but you seem like a nice guy.....

Ok, think of a beer case, eh. Now as you know, the beers are arranged 4 abreast and 6 long. 6 times 4 is 24 - no problem. In fact, its a beauty. But 6 divided by 4 is 1.5. Any beer drinker knows that it is physically impossible to drink 1.5 beer. No bout a doubt it, you are going to drink the full 2 beer, eh. That leaves you with 22 beer. (Unless your buddy Blair is over, then there would be 20) Now, 20 divided by 6 is 3.3. Do you see the patern taking shape here? There is no easy solution but to drink the whole box, bye. And that's were the problem lies, eh.

So there you go. Now you understand why the room dimensions are so important.

Actually, it has to do with the wavelengths of certain frequencies.

Quote:

If the wavelength of a particular note happens to be the same, or an even fraction (1/2, 1/3, ¼, etc.) as one of the room’s dimensions, there’ll be a standing wave created. Standing waves cause certain frequencies to be accentuated at various locations in the room and reduced in others. Basically it can cause one seat in the room have great sound and another to have very poor sound.

In order to reduce the effects of standing waves, it is best to have the room follow certain dimensional ratios. (ratios of HxWxL). First of all, run & hide from a room that is a perfect cube. You should avoid rooms with any ratios that are perfect multiples of each other. An example of a poor room would be a 15’ x 20’ room with a 10’ ceiling. Some good ratios are 1 x 1.3 x 1.7 or 1 x 1.3 x 1.9 or .9 x 1.3 x 1.6. It is easier to work with a rectangular room because the good speaker and seating locations are easier to predict.







Shawn

Epic 80/600 + M3's + M3 Algonquins + M2 Computer + EP125
I think I'm developing an addiction.
Re: Sub-woofer placement
SirQuack #159186 02/19/07 10:58 PM
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Quote:

12ft x 12ft x 12ft is not good

24ft x 12ft x 6ft is not good

22ft x 12ft x 8ft YOUR room, I don't think you will have to many problems, unless you have bare walls.




See, there you go. I was reading 12x22, but my brain kept thinking 12x24. I should just stop posting today, and go to bed.


Shawn

Epic 80/600 + M3's + M3 Algonquins + M2 Computer + EP125
I think I'm developing an addiction.
Re: Sub-woofer placement
real80sman #159187 02/20/07 12:18 AM
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Quote:

Ok, think of a beer case, eh.






::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Sub-woofer placement
MarkSJohnson #159188 02/20/07 05:29 PM
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I am getting absolutely NO LFE from my beer (well, maybe a little bit the next day ). The bigger disappointment is that my subwoofer doesn't dispense beer.

Re: Sub-woofer placement
Ray3 #159189 02/22/07 09:51 PM
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wow.. who ever knew listing to music or movies was so complicated. I guess that's why a bottle of Johnnie Walker is rectangular - better acoustics when the scotch hits the ice and slides into the glass like my hands over the curves of a womans great pair of hips .... oh, was that out loud??

Last edited by agentfox1942; 02/22/07 09:52 PM.

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Re: Sub-woofer placement
agentfox1942 #159190 02/28/07 04:44 AM
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Here's another way to think of it, your entire room becomes the inside of a speaker, so to say. Alot of speaker companies try very hard to design unique cases to stop standing waveforms(Axioms design does this) so if your room is perfectly/evenly shaped you could have this standing waveform problem.


Jason
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Re: Sub-woofer placement
MarkSJohnson #159191 03/05/07 06:42 PM
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"12ft x 12ft x 12ft is not good
24ft x 12ft x 6ft is not good
22ft x 12ft x 8ft YOUR room, I don't think you will have too many problems, unless you have bare walls."
But these have a common devisor by 2's. Or
21x12x9 by 3

Isn’t the idea to have no divisible lengths...... 23x13x7 or 23x12x7 or 19x11x8?


Last edited by axiom_man; 03/05/07 06:44 PM.

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Re: Sub-woofer placement
axiom_man #159192 03/06/07 03:41 AM
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Troy, the significant factor actually isn't not having a common divisor, but rather not having the dimensions be the same or exact multiples of each other. So, the 22'x12'x8' room dimensions all being divisible by 2 isn't significant; they have the relationship of 2.75x1.5x1, which is okay.


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Enjoy the music, not the equipment.


Re: Sub-woofer placement
axiom_man #159193 03/06/07 10:42 PM
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It is also important that the numbers aren't divisable by themselves easily

12 does not go into 22
8 does not go into 12 or 22


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Re: Sub-woofer placement
SirQuack #159194 03/07/07 03:22 AM
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If you're fundamentally lazy like me, you can download the "Graphical Mode Calculator" from Ethan Winer's "RealTraps" site, plug in some room dimensions, and look at the graphs to see how the different room resonances pile up at different frequencies.

An ideal room has the resonances (modes) evenly spaced. Nobody has an ideal room unless it was designed and built from scratch for audio use, so don't worry if they bunch up in a couple of places. Those will be the "problem" frequencies and you can do things with subwoofer placement to help with them.

http://www.realtraps.com/info.htm


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