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Plywood thickness for 15 inch subwoofer
Plywood thickness for 15 inch subwoofer
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Old 5th February 2018, 09:03 AM   #51
S4m is offline S4m  Germany
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Heyho,
I collected some experience with subwoofer builds with/without bracings.
The last woofer enclosure i built needed to be very stiff because a 18 inch woofer
from a carhifi enthusiast needed to be transformed into a downfiring hometheater sub.
At first, we made a simple enclosure without bracing and it was horrible sounding.
The walls seemed to work like membranes (22mm plywood).
Then we made some triangles and put two of them per side without huge success.
After I made a bracing as Dave said with connecting the driver by felt to the bracing
the situation was absolutely good and the whole sound went from rattling/muffling
to nice more or less clean bass.
I would guess(without any measurements!) that in planning any kind of box implementing a bracing brings you to a result that you are expecting.
In the end it's only a little bit more sawdust
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Old 5th February 2018, 11:03 AM   #52
Brian Steele is offline Brian Steele  Grenada
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Originally Posted by globalplayer View Post
Not in my experience.
There is a difference.
You will hear it.
Yup. In my experience, adding braces makes a subwoofer sound significantly better (tested with my POC #2 design).
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Old 5th February 2018, 11:29 AM   #53
scottjoplin is offline scottjoplin  Wales
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Originally Posted by globalplayer View Post
Internal bracing will cause "turbulences" and will make the sound somewhat "ugly" in my experience.
Wouldn't turbulences be an advantage?
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Old 5th February 2018, 09:27 PM   #54
Think is offline Think  Netherlands
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Plywood thickness for 15 inch subwoofer
Quote:
Originally Posted by Brian Steele View Post
Yup. In my experience, adding braces makes a subwoofer sound significantly better (tested with my POC #2 design).
LOL, that's not what he meant, but you are right.
It's all about the stiffness of the box or minimizing warp in the flat panels of the box.
You can build a canoe with bracing that weighs 20/30lbs or without; then you have model hollowed out tree trunk weighing over 200 lbs; both work.
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Old 6th February 2018, 05:05 AM   #55
globalplayer is offline globalplayer  Germany
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Quote:
Originally Posted by Brian Steele View Post
Yup. In my experience, adding braces makes a subwoofer sound significantly better (tested with my POC #2 design).
LOL!
That`s not what I meant.
Of course bracing will help when using "thin" walls.

But in my 6th orders internal bracing would make them sound "ugly" as opposed to the clean sound without bracing.
Enough wall thickness will preserve the clean sound while adding sufficient strength.
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Old 6th February 2018, 01:47 PM   #56
Think is offline Think  Netherlands
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Plywood thickness for 15 inch subwoofer
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Originally Posted by globalplayer View Post
LOL!
....
But in my 6th orders internal bracing would make them sound "ugly" as opposed to the clean sound without bracing.
Enough wall thickness will preserve the clean sound while adding sufficient strength.
Have you tested this with 2 boxes with the exact same internal volumes, 1 with and 1 without braces?
I think that there is probably something else going on like the braces taking up space/volume, or a brace near a port obstructing airflow.
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Old 6th February 2018, 04:07 PM   #57
globalplayer is offline globalplayer  Germany
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Originally Posted by Think View Post
Have you tested this with 2 boxes with the exact same internal volumes, 1 with and 1 without braces?
I think that there is probably something else going on like the braces taking up space/volume, or a brace near a port obstructing airflow.
It was just one box, close to leave prototype state.
I listened to it without bracing, then added bracing in the hope of more db (it was loud already but if you can get more) which went up significantly in higher bass notes.
Listened to it again.
Removed bracing.
All fine again.
Albeit not as rigid.

I think it was a combination of the above^^ since 6th order bps are very unforgiving regarding chamber volumes, etc. both chambers influence each other, ...

It had somewhat more "punch" but sounded somewhat "ugly" with bracing and low end suffered/clarity.
So I removed it.

Being still a MDF prototype which worked surprisingly well it gets occasional use in-car where it is very efficient even with only 100 watts.
Since then I moved on to other BP6 designs which are more rigid due to shape/construction.
Still no internal bracing as of yet.
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Old 6th February 2018, 04:14 PM   #58
nigelwright7557 is offline nigelwright7557  United Kingdom
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If there is bracing then I would expect to get more reflections of the sound off the rear panels reflected back to the speaker and affect the sound.
Ideally there should be no reflections off the back panels that's why internal padding/sound deadening is often used.
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Old 7th February 2018, 12:20 AM   #59
Brian Steele is offline Brian Steele  Grenada
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Originally Posted by nigelwright7557 View Post
If there is bracing then I would expect to get more reflections of the sound off the rear panels reflected back to the speaker and affect the sound.
Ideally there should be no reflections off the back panels that's why internal padding/sound deadening is often used.
Adding stuffing or lining to a bandpass subwoofer can reduce the out of band noise. However, it can also reduce the efficiency of the subwoofer. There are better ways of reducing the out of band noise. I've discovered for example that careful positioning of the vent's opening in the vented chamber can null out the first (and most annoying/audible) out of band resonance.
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