# Perfect Square enclosures sound bad???



## Ultimateherts (Nov 13, 2006)

I was reading somewhere on the web about enclosure building for subwoofers and it made it a point to say that you never want an enclosure to be a perfect square.

My question is why? It this a myth? Is this bull kaka?


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## Navy Chief (Jun 14, 2010)

I have also read this and have tried to avoid square enclosures for years. It is my understanding that a perfectly square enclosure allows rear waves inside the enclosure to bounce at equal lengths inside the box due to all the equal length parallel surfaces, this in turn leads to cancellation as those waves intersect each other. I dont know how true the theory is so I am not saying I believe it or not, I have just heard of it.


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## thomasluke (Jun 10, 2011)

Think about this guys. How long are the waves we are talking about?


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## SHAGGS (Apr 24, 2011)

Twenty some odd feet.
I was under the impression that sqaure is ok, as long as you don't mount the sub in the very center. 
Shifting it to the side allows the rear waves to reflect at different angles and distances.
Patrick prolly has some input, not to mention a bunch of graphs and math, that hurt my brain.


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## Hillbilly SQ (Jan 26, 2007)

There was a guy that built all his customers sub boxes to golden ratio formula unless the customer needed something super custom. I just build to fit where it needs to go.


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## thehatedguy (May 4, 2007)

For an automotive sub enclosure...I wouldn't worry about it.


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## Chaos (Oct 27, 2005)

When it comes to full range loudspeaker cabinets, this isn't exactly a myth - nor are the effects easy to distinguish by ear alone.

As far as mobile subwoofer enclosures are concerned, it is pretty much a non-issue.


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## rreed (Mar 9, 2012)

Why are all home theater subs in cube (square) boxes w/ the driver mounted in the center and work perfectly fine? Been that way for a long time whether cheap-o stuff or expensive high-end (no pun intended).

Since I can remember I've always noticed boxes that are the golden ratio have the best sounding and loudest/best bass.

For car audio I've always gone w/ a wedge, either behind pickup seats (skinny wedge) or in the cargo area (big wedge) because of fear of standing waves. And to help things fit, a-la Hillbilly SQ there. 

I don't know why I've shrugged my shoulders at home theater subs being square and not having any issues and being happy w/ that but for vehicle sub boxes I always slant the face and hope I don't get any dead spots anywhere inside the listening area.


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## PPI_GUY (Dec 20, 2007)

Don't know about square speaker (sub) boxes but, back in the day we used to internally dampen the corners of very large sub boxes, i.e. 15" and above. One of the guys I hung around with had read an article about standing waves and was certain that adding acoustic foam to the corners inside the enclosure actually helped. 
I seriously doubt it did anything beyond acting as expensive polyfill but, his boxes were tremendously loud and tight sounding.


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## jcpahman77 (Mar 5, 2013)

Golden Ratio for enclosure dimensions
Good article on the Golden Ratio.

I'm sure there about as many reason right as there are wrong about why standing waves don't impact home subs but my guess would be it's just what we're used to hearing, therefore we don't know there is anything wrong. Similarly, a good enclosure should be internally braced to keep the walls of the enclosure from flexing. For a sub in a car, probably not a problem. Most distortions or colorations of these types will be negligible and likely impossible to discern due to cabin gain.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

^how do you get a standing wave in an enclosure, when the wavelength (or even the quarter wavelength) is larger than the box? Even if you run your subs to 100hz, you'd need square box with 33.75" long walls to fit the quarter wave inside it.


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## PPI_GUY (Dec 20, 2007)

TOOSTUBBORN2FAIL said:


> ^how do you get a standing wave in an enclosure, when the wavelength (or even the quarter wavelength) is larger than the box? Even if you run your subs to 100hz, you'd need square box with 33.75" long walls to fit the quarter wave inside it.


I didn't say we were very smart back then...just that we _thought_ we were onto something. LOL! :laugh:


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## jcpahman77 (Mar 5, 2013)

I would say, what you can do to improve the box in a car would be bracing and stuffing or lining depending on the box type (stuffed for sealed, lined for vented). Also, it's been 15 or 16 years since I've done the math to calculate the length of a sound wave at a given frequency, so I was simply responding to the general question of my home subs that are square don't seem to suffer from standing waves.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

PPI_GUY said:


> I didn't say we were very smart back then...just that we _thought_ we were onto something. LOL! :laugh:


Lol, the stuffing probably did help as an expensive polyfil. 

I'm working on something now that involves the golden ratio in a car, as soon as I get things figured out I'll post in my project log. Wont really help bass, but could help the midbass hole (or in my case, huge peak) that most people seem to have. Of course, for most people, it would be un-usable.


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## jcpahman77 (Mar 5, 2013)

I have such trouble with mid-bass in my car. It's either completely absent or so overbearing that I wish it wasn't there at all. I'm hoping the new driver's I have planned to install will help, but I look forward to your build and input towards this end.


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## rreed (Mar 9, 2012)

Ooo! Yeah I forgot about internal bracing supposedly helps break up or diffract standing waves. I suck at math and am going by beliefs of the time--as late as the 1990s so I'm not going to argue any points about standing waves being 33.75" long--I have no idea what you just said but will go along w/ it. 

But anyways, as far as home subs being in a square box I've found placement affects the sound more than anything else. Once I find a good spot for it (in or near the corner for me, and experiment w/ directional pointing from there) I tweak the gain and x-over point. I don't recall noticing dead spots once I get it in a good place.

I also forgot way back in the early 90s, not knowing any better but noticing home subs were perfectly square, I took some leftover 1/2" plywood (stop laughing) and built a ~1 cu. ft. box w/ 13x13 pieces to mount this old 8" woofer. No internal bracing or fill of any kind, just a large ~1 cu. ft. internal space cube. I kept and used that thing for years, mounting several different woofers by simply laying a different front cover over it for different woofer sizes. Worked great! Same as usual, try to place it near the corner as possible and point whichever direction until it sounded good. One living room I lived in did have a good dead spot in one of the side chairs but not sure that was the box or the room, it never happened any other room.

I understand using triangle-shaped acoustic foam in recording studio room corners is supposed to drastically help kill echos, noise, etc. so it stands to reason it might help in a subwoofer enclosure? I dunno, we're talking about vocals, guitars, etc. vs. deep throbbing subwoofers here.

As I did a lot when I was a kid, experiment to see what works best for you.


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## syc0path (Jan 23, 2013)

TOOSTUBBORN2FAIL said:


> ^how do you get a standing wave in an enclosure, when the wavelength (or even the quarter wavelength) is larger than the box? Even if you run your subs to 100hz, you'd need square box with 33.75" long walls to fit the quarter wave inside it.


True, but keep in mind that the sound waves don't just disappear when they hit the internal walls of the box. They bounce back and forth and therefore can cover the distance of their wavelength. So they can affect response. If all the walls are equidistant from the sub, then certain freqs will be reinforced and certain freqs will be at least partially cancelled.

That being said, the reflected waves are usually disturbed by the continued movement of the sub cone, which significantly reduces their effect. In my experience, sub box shape does make a difference in the sound, but it's so minor that most people wouldn't notice.


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