First sub build - not sure how to do bracing

[YonathanZ]

Hi,

Here's a screenshot of the sketch of my box:

An externally hosted image should be here but it was not working when we last tested it.

I'm not sure how to approach bracing. I've seen photos of DIY builds and their bracing, but where do I start? I assume that bracing should fit the box size but I don't know what the "rules" or basics of it are. As in, how much is enough and how much is too much.

And does the she or length of it matter acoustically? Can it affect the frequency response?

Thanks.

 

[DaveThreshold]

Hi,

Here's a screenshot of the sketch of my box:

An externally hosted image should be here but it was not working when we last tested it.

I'm not sure how to approach bracing. I've seen photos of DIY builds and their bracing, but where do I start? I assume that bracing should fit the box size but I don't know what the "rules" or basics of it are. As in, how much is enough and how much is too much.

And does the she or length of it matter acoustically? Can it affect the frequency response?

Thanks.

Have you built the box yet? I do not understand the two extra panels on the bottom.

1. All bracing cubic capacity must be calculated and subtracted from your internal box size.
2. For a SUBWOOFER BOX, I would not use MDF. I would use high quality marine plywood, or a high quality plywood equivalent. They say to use MDF, but that is to suppress midrange, and upper bass noise more than anything. MDF will still flex with extreme bass.
3. From the picture, you have made it difficult. I would normally start with 1 1/2 X 1-1/2” brace from top to bottom, side to side, front to back, connected in the middle. I used rock-maple or oak, and it never fails.
There are a ton of ideas in the link below, and I’m sure a ton of theory also.

When it comes to speaker enclosures, I learned this from Martin Colloms: He said speaker box resonance (meaning noise from the box walls flexing, and coloring the sound when it hits your ears) should be viewed as a signal to noise ratio! He means the ratio of direct sound from the drivers compared to the miniscule sound of the enclosure walls flexing. IMO, the best box ever invented was the B&W 802-N (now through the D-3’s). Stereophile tested it as they do all speaker boxes with an accelerometer. Every other speaker, including many 300 pound Wilsons, always showed a very noticeable bunch of hash in the water-fall plots. The 802’s showed almost NOTHING. They are an abject lesson on the best box available.
BUT: All of that is not necessary to make the external box coloration a non-issue. A 180 pound box is NOT necessary either. Thick, stiff, box walls and good bracing should get any flexure-coloration down to a level that is completely inaudible.
I hope this helps.
With your design, it is very hard to have bracing the way that I described.

https://www.google.com/search?q=sub...2&ved=0ahUKEwiksbWphuTOAhVDNSYKHddfDfIQsAQIGw