Box Design

[quackhead 10+ year member]

I havent got any "real" midrange, still have the factory speakers -- ***** i know--- I think I can get by tho for now..

I think ill take your and bucks advice and try that common chamber design and make the port 3" instead of 2 . should I keep it (the port) 22 inches as drawn?

also my geometry doesnt add up.. i drew the top board wrong it is supposed to rest on top of the side to equal 31.5 (27.75+3+.75).

here is what I come up with:

External dimensions: 18"H x 31.5"W x 20"D = 3.6 cubes net. with the port 3" x 18.5" = 55.5 sq" of port

With the port 39" long, you will see a tune of 30hz.

Response Curve:

 

[quackhead 10+ year member]

I hope someone like @Buck can double check and verify my geometry as well...maybe offer some advice on the the R's and what they really like.

 

[Mongo12 10+ year member]

sounds good ill change the plans and go with that. unless buck disagrees //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif thanks for the help. without your work it'd have been trial and error and alot of wasted mdf

 

[dbeez 5,000+ posts]

How tall is the box

 

[quackhead 10+ year member]

here is what I come up with:External dimensions: 18"H x 31.5"W x 20"D = 3.6 cubes net. with the port 3" x 18.5" = 55.5 sq" of port

With the port 39" long, you will see a tune of 30hz.

Response Curve:

\.

 

[Mongo12 10+ year member]

ok so not to sound dumb.. but is the port 18.5 inches or 39 inches in your graph? or would i have to add 20.5" to the 18.5 inch port to get 30Hz?

30hz sounds good to me since the probox is (i was told) tuned to around 45..

the redline is scaled to 18.5 inches and the yellow shows where it would be at 39 inches .. unless i misunderstood your dimensions.

 

[Buck 5,000+ posts]

I would do like 4.5-5 cubes.

 

---------- Post added at 07:04 PM ---------- Previous post was at 07:04 PM ----------

 

What program is that?

 

[Buck 5,000+ posts]

The 4.5-5 cubes is personal tastes, the 3.6 will work.

 

[Mongo12 10+ year member]

will the 3.6 be tuned lower than the probox? and any ideas on the port should it be 18.5" or the ?39"? thats got me tripping

 

[Buck 5,000+ posts]

The port should be around 39. I would like to see a shorter box or a different port style to get rid of the 3 wide and 18.5 tall, I'd like more 12 tall, 4.5-4.75 wide to keep the same port area. But that'd if you can fit the extra depth/width.

 

[quackhead 10+ year member]

I would do like 4.5-5 cubes. 

---------- Post added at 07:04 PM ---------- Previous post was at 07:04 PM ----------

 

What program is that?

I used Final Calculator to work out box and port, then use UniBox408 to map it

 

[quackhead 10+ year member]

The port should be around 39. I would like to see a shorter box or a different port style to get rid of the 3 wide and 18.5 tall, I'd like more 12 tall, 4.5-4.75 wide to keep the same port area. But that'd if you can fit the extra depth/width.

you think with the dems he has and the port up/sub up it would be better to go Precision port?

 

[Buck 5,000+ posts]

He could do a single 6".

 

[Mongo12 10+ year member]

the precisions are 6" x 18" could one use pvc or do you really get the gains they say using the $40 tube they sell

also id have to add 3" to the width, that will work but 34" is the max width I can go. Would that xtra cubes make a difference?

and since the box is 18" tall, how much space is required below the bottom of the port and the bottom of the box?

 

[quackhead 10+ year member]

the precisions are 6" x 18" could one use pvc or do you really get the gains they say using the $40 tube they sellalso id have to add 3" to the width, that will work but 34" is the max width I can go. Would that xtra cubes make a difference?

and since the box is 18" tall, how much space is required below the bottom of the port and the bottom of the box?

If you can do that extra width, now we are getting somewhere, assuming you still want subs up/port up configuration. Going back to the original design using these external dimensions:

20" tall x 34" wide x 22" deep, the top of the box, where the subs and port opening will measure an overall 34" x 22"

With the slot port at 4" wide and 20.5" across (22" - 1.5") make the port the same overall 39" long inside the box (except using the 4" design, instead of the 3") as post # 21, you will be at 4.8 cubes/net @ 31hz tuning and have less port noise introduced. This is a closer match to Buck's recommendations