If I have a sub with a recommended sealed enclosure volume of 1 cu.ft., and I build one enclosure with inside dimensions of 12"x12"x12", and I build a 2nd enclosure with dimensions of 15.2"x12.07"x9.58" (the Golden Rule), will I notice a discernable difference between the two?
Replies (8)
swez on 04/26/2005 11:27:21
Probably not a big difference in sound. The 2nd enclosure may sound a tad deeper as it is larger then the 1st box. You may want to calculate the sub displacement and factor that into your box equations as well.
Assuming the box is 1.0 ft^3, need to deduct (subtract) the sub displacement from the 1728 in^3 to get a very accurate measurement. However, if you are a little short, adding ~1# of polyfil will make the box seem ~10% larger than it really is physically.
Other than that, you are pretty much on target. A sub will be fine within 10% +/- of recommended specs.
Swez
MrBrownstone on 04/26/2005 13:24:18
Stay away from the cube shape, but you shouldn't notice any difference.
gearhead on 04/26/2005 14:00:52
What is "wrong" with a cube shape?
Another question. Will speaker grilles (perforated metal) on a subwoofer have any major effect on volume? Sound quality/diffusion?
ttocs on 04/26/2005 14:01:54
no
swez on 04/26/2005 18:58:51
In the olden days, it was suggested to avoid cube box designs for Hi-Fi as there was too much standing wave problems with older subs. In the compact sub market of car audio today, cubes are acceptable, but you still have to deal with the standing wave issues. This is where polyfill can help diffuse that issue.
Swez
gearhead on 04/27/2005 01:24:52
OK, I'll bite. What are standing waves, why are they detrimental, and how do I get them to lay down?
swez on 04/27/2005 06:56:23
Standing wave will lie down when we use polyfill. hehe (acoutical dampening materials)
A standing wave is a series of nodes that build up inside the enclosure which in turn, tend to cancel out certain frequencies the speaker tries to put forth as music and harmonics. They just get trapped inside the enclosure and hinder or boost frequency nodes and decrease overall accuracy.
This phenom is well documented in live sound scenarios. Standing wave can happen in speaker enclosures as well as listening spaces. Think of an audio track as a series of ping-pong balls, bouncing around in a box and colliding. Signals (balls) leave the rear of the woofer cone, hit the back and side walls and collide. As a result, these will cancel each other out, inside the box. That's a basic, if not lame way to explain standing wave issues.
Oh, grill covers are acoustically transparent too. Use them to protect your expensive speaker come from damage.
Swez
MrBrownstone on 04/27/2005 12:46:57
Depends on the size. twin 15" woofers could have some issues...mostly when you get in the multiple cubic foot sized boxes.
Replies (8)
swez on 04/26/2005 11:27:21
Probably not a big difference in sound. The 2nd enclosure may sound a tad deeper as it is larger then the 1st box. You may want to calculate the sub displacement and factor that into your box equations as well.
Assuming the box is 1.0 ft^3, need to deduct (subtract) the sub displacement from the 1728 in^3 to get a very accurate measurement. However, if you are a little short, adding ~1# of polyfil will make the box seem ~10% larger than it really is physically.
Other than that, you are pretty much on target. A sub will be fine within 10% +/- of recommended specs.
Swez
MrBrownstone on 04/26/2005 13:24:18
Stay away from the cube shape, but you shouldn't notice any difference.
gearhead on 04/26/2005 14:00:52
What is "wrong" with a cube shape?
Another question. Will speaker grilles (perforated metal) on a subwoofer have any major effect on volume? Sound quality/diffusion?
ttocs on 04/26/2005 14:01:54
no
swez on 04/26/2005 18:58:51
In the olden days, it was suggested to avoid cube box designs for Hi-Fi as there was too much standing wave problems with older subs. In the compact sub market of car audio today, cubes are acceptable, but you still have to deal with the standing wave issues. This is where polyfill can help diffuse that issue.
Swez
gearhead on 04/27/2005 01:24:52
OK, I'll bite. What are standing waves, why are they detrimental, and how do I get them to lay down?
swez on 04/27/2005 06:56:23
Standing wave will lie down when we use polyfill. hehe (acoutical dampening materials)
A standing wave is a series of nodes that build up inside the enclosure which in turn, tend to cancel out certain frequencies the speaker tries to put forth as music and harmonics. They just get trapped inside the enclosure and hinder or boost frequency nodes and decrease overall accuracy.
This phenom is well documented in live sound scenarios. Standing wave can happen in speaker enclosures as well as listening spaces. Think of an audio track as a series of ping-pong balls, bouncing around in a box and colliding. Signals (balls) leave the rear of the woofer cone, hit the back and side walls and collide. As a result, these will cancel each other out, inside the box. That's a basic, if not lame way to explain standing wave issues.
Oh, grill covers are acoustically transparent too. Use them to protect your expensive speaker come from damage.
Swez
MrBrownstone on 04/27/2005 12:46:57
Depends on the size. twin 15" woofers could have some issues...mostly when you get in the multiple cubic foot sized boxes.
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