Help on 2 10" Design (Labyrinth + Flare/Kerf)

[ARSkemp 10+ year member]

Here's a couple pics of the design, 2.56 ft^3 tuned to 36hz w/45 sq inches of port area for two 10" Alphas:





My question is regarding the port length, i need it to be 31" long to tune to 36hz.

I've read you should start the port length halfway down the flare (flare radius = 3.5"), and then add on 1/2 the port width (3") if your port shares a wall with the box.

Does this picture look correct with regards to port length (the dashed line).



I also wasn't sure if the inside flare affected port length as well...

Thanks in advance for the help, this will be my first time doing a flare, and my first time doing a labyrinth type port.

Click to read more...

 

[Rashaddd 5,000+ posts]

yes the flare does somewhat change length because it changes where the center of the port is, I'd guess in this case it'll be maybe .5-1" shorter max by looking at the pic, if even that, so I'd just add an extra inch or half an inch to your last port piece and you'll be close enough

 

[groundpound4200 5,000+ posts]

I'd put some 45s in the corners too. I did a labyrinth box like that once and I wish I had done it.

 

[ARSkemp 10+ year member]

I'd put some 45s in the corners too. I did a labyrinth box like that once and I wish I had done it.

one of the recent threads about 45's said that it would be better to leave them out //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[ARSkemp 10+ year member]

yes the flare does somewhat change length because it changes where the center of the port is, I'd guess in this case it'll be maybe .5-1" shorter max by looking at the pic, if even that, so I'd just add an extra inch or half an inch to your last port piece and you'll be close enough

So the port length would probably be more like this, right?

 

[groundpound4200 5,000+ posts]

one of the recent threads about 45's said that it would be better to leave them out //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

link? I guess in my box when I stuck my hand in the port, the air only seemed to move in the very middle of the port. If i put my hand back where the 45s would go there was no air movement at all. I would think putting 45s in helps keep the port width more constant.

 

[THUMPPER 10+ year member]

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[ARSkemp 10+ year member]

link? I guess in my box when I stuck my hand in the port, the air only seemed to move in the very middle of the port. If i put my hand back where the 45s would go there was no air movement at all. I would think putting 45s in helps keep the port width more constant.

http://www.caraudio.com/forum/showthread.php?t=378480

I was reading another thread (i forgot the name of the title of it) that had a couple people saying that they metered slightly less when using 45's and that unless you are going to be testing the box with 45's in and with 45's out than just leave them out.

Not everything was port specific, most of it was about 45s in the main chamber of the box, but still...

 

[ARSkemp 10+ year member]

link? I guess in my box when I stuck my hand in the port, the air only seemed to move in the very middle of the port. If i put my hand back where the 45s would go there was no air movement at all. I would think putting 45s in helps keep the port width more constant.

http://www.caraudio.com/forum/showthread.php?t=378480

I was reading another thread (i forgot the name of the title of it) that had a couple people saying that they metered slightly less when using 45's and that unless you are going to be testing the box with 45's in and with 45's out than just leave them out.

Not everything was port specific, most of it was about 45s in the main chamber of the box, but still...

and Thumper, thats a nice box! This is going to be 3rd box i've ever made before, and first time using kerfing, so i don't think i'm skilled enough to make one quite as nice as that one //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Rashaddd 5,000+ posts]

big difference between 45's in the compression chamber of the box and 45's in the port.

The only way you could gain by NOT having 45's in the port is if you're either doing them wrong or something abnormal about the port is giving you a gain (which isn't impossible), but it's best in most cases to shoot for perfect port width throughout

and yep the way you redrew that is the way it would be

 

[ARSkemp 10+ year member]

big difference between 45's in the compression chamber of the box and 45's in the port.
The only way you could gain by NOT having 45's in the port is if you're either doing them wrong or something abnormal about the port is giving you a gain (which isn't impossible), but it's best in most cases to shoot for perfect port width throughout

and yep the way you redrew that is the way it would be

alright, thanks for the help.

I ended up increasing the last port wall by 1" after accounting for the inside flare which changed the box to 2.53ft^2 tuned almost exactly to 36hz.

I just got a circular saw for xmas, so this will be my first real chance to use it //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif.

I'm going to be double baffling the top, but i've been debating on whether to flush mount these or not, since all i have is a jigsaw ( no router //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif).

 

[Rashaddd 5,000+ posts]

alright, thanks for the help.

I ended up increasing the last port wall by 1" after accounting for the inside flare which changed the box to 2.53ft^2 tuned almost exactly to 36hz.

I just got a circular saw for xmas, so this will be my first real chance to use it //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif.

I'm going to be double baffling the top, but i've been debating on whether to flush mount these or not, since all i have is a jigsaw ( no router //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif).

I used to cut holes with a jigsaw before I got a router, definitely soooooo much nicer with a router, but with a jigsaw if you can take your time and draw out a proper circle and just follow the line and do a little sanding you can get it just about perfect to the eye