Please help me on box calculating and tuning

[GCAdidas13 10+ year member]

I'm designing a build-in for an Avalanche 15. I am only building one side for now, and a second side will be added at a later time.

In my book it comes out to be 3.9 cubes or so tuned to just under 27 hz. I haven't factored in bracing OR sub displacement, so volume will be lower, and tuning a little higher.

Let me know what you think!

EDIT: INTERNAL HEIGHT IS 16"

Click to read more...

 

[req 5,000+ posts]

any comments on the bottom left?

put a center line down the whole port and make it a red dotted line so we can actually SEE where your port goes.

 

[bcarpenterfhl 10+ year member]

i got a volume of 3.47 cubic feet (without sub displacement), a port length of 47.37, and a frequency of 28.49 Hz. i could be wrong, but i dont think so.

 

[req 5,000+ posts]

looks good to me then //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[GCAdidas13 10+ year member]

roger that! i'm gonna do some last minute adjustments and recalculate the box volume and tuning, and build it saturday hopefully.

 

[GCAdidas13 10+ year member]

BuuuuuuuuuuuuuMP

 

[GCAdidas13 10+ year member]

Can someone please run through this one more time?

Today I plan on constructing a cardboard model into the trunk of my car for the outer dimensions, after i design an enclosure with nicer numbers //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

if bhcarpenter fhl is correct i think i am going to add an inch on the depth (add inch to port and an inch to the depth of the enclosure) to drop my tuning a little more.

But I'll do the calculations again today and see if that's necessary.

 

[UndercoverPunk 5,000+ posts]

The port looks a little small to me, but I just like HUGE ports. I havn't actually checked it, but it looks good to me:thumbupw:

 

[GCAdidas13 10+ year member]

The port looks a little small to me, but I just like HUGE ports. I havn't actually checked it, but it looks good to me:thumbupw:

3.5x16" isn't big?

56 square inches of port for a single 15" sub isn't big?

whoooa

 

[I want SExxx 10+ year member]

I'm gunna tell u right now brian that your port is gunna resonante like a mother somewhere between 55-70hz being as long as it is. you NEED to do curves or 45's in ALL corners to help eliminate this. Call up chad and have him model your box in leap and get his input BEFORE you build.

 

[swimfreak26 10+ year member]

Bcarpenter....you are WRONG! It's tuned to 28.51Hz accroding to my calculations. J/k man //content.invisioncic.com/y282845/emoticons/toast.gif.bc0657bf54b9ee653b6438524461341e.gif ...box looks good, should be right around 3.25 cubes tuned at 29.4ish Hz once you throw in the sub. If you brace it'll change it a little more, but you're looking over all around 3.2 cubes at 30Hz, or thereabouts.

 

[ngsm13 5,000+ posts]

Yup, it's looking good. I also recommend to round the corners...if you could get ahold of a PVC pipe...cut it...put vaseline on the outside...screw it in the corner...then poor resin down in it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Or you could cut 45's //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

NG

 

[GCAdidas13 10+ year member]

I'm gunna tell u right now brian that your port is gunna resonante like a mother somewhere between 55-70hz being as long as it is. you NEED to do curves or 45's in ALL corners to help eliminate this. Call up chad and have him model your box in leap and get his input BEFORE you build.

i can't have any pre-fab boxes. the outer dimensions of my box are the max that they can be, without giving me any problems.

and i intended on doing 4-7" PVC pipe to make really nice curves down the inside of my port, and cut the ends of the port on both sides with a 1/2" rounded edge router bit.

and thank you for your calculations, Swimfreak. I think I am going to add an inch or two for the length of the box (up and down) and then recalculate my size and tuning, and that will be after school today. I really need this to be up and running, and SOON!

 

[bean 10+ year member]

Going to RTTI on wed......... This'll be the third time.. This thread reminded me of something I learned from them a couple years ago. SEXXX is right about getting rid of 90 degree angles. The thing I like to do (learned from RTTI) to round the corners is mis up a batch of bondo. Goop it into the corners. Take somgthing round and hollow. Soda can with the top cut off for example. Scrape the exess bondo gooo from the corners leaving a rounded interior edge. Sand a little, maybe pait it to make it smooth. Often these rounded corners will give up to 3dB gain.....

Just a thought. GL Brian

 

[ngsm13 5,000+ posts]

Going to RTTI on wed......... This'll be the third time.. This thread reminded me of something I learned from them a couple years ago. SEXXX is right about getting rid of 90 degree angles. The thing I like to do (learned from RTTI) to round the corners is mis up a batch of bondo. Goop it into the corners. Take somgthing round and hollow. Soda can with the top cut off for example. Scrape the exess bondo gooo from the corners leaving a rounded interior edge. Sand a little, maybe pait it to make it smooth. Often these rounded corners will give up to 3dB gain.....
Just a thought. GL Brian

AHEM...

Yup, it's looking good. I also recommend to round the corners...if you could get ahold of a PVC pipe...cut it...put vaseline on the outside...screw it in the corner...then poor resin down in it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Or you could cut 45's //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

NG

//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif And it won'd give you THAT much of a gain...but it'll git rid of some un-wanted resonance...and it'll give you a little more output...

NG