OK lets try this 2 way Morel

Madmike2

Member
2005-04-24 11:55 pm
Toronto
How about this. My math wasnt fuzzy except on the stuffing. (i hope) i have no shame so i cant be embarrased. As you all know i have been looking for BIG and SQ not really the SPL but loud is good if it sounds good. Here is a couple hours reading and using some formulas i found and coming up with THIS ....tada
 

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Ok i am having a little difficulty here i got half of this cut already but something came to head in my mind last night.

For the labrynth length, do i measure the inner dividers or do i make an imaginary line in the middle of the labrynth and call that the length ? Thanks guys for any help.
 
I think it's probably too long unless you just want to stuff it fully and get essentially an aperiodic cabinet. I actually think low Q sealed sounds better.

Did you stuff the dimensions into MJK's mathcad sheet? You'll need to use the "sections" one if you want to keep all the weirdness.

My suggestion is to try something closer to 'classic' TL length, 72"/2m-ish, with single fold, or maybe one 180 and 90 fold at the exit.

Best to space the driver from the end a bit. 1/5 usually is good. Line length is a line down the center...

GB
 
OK so line length is a line down the center. Thanks.

Now the way i understand it, you take the driver Sd and desired Frequency tuning and and use that to get the length of line. The sealed end of the line should be approx 1/6 the Vas, and that none of the pinch points/turns what ever and the exit should never be less then the SD of the driver.

I am i misunderstanding something here? I dont understand how 72 inches applies to any driver. :confused:
 
Isn't the line length for your desired tuning frequency (Fs I presume) dependent on the geometry of the line itself? i.e. straight or expanding/contracting taper. Looking at MJK's tables the SD/S0 ratio (which determines the taper) massively affects the line length for a given tuning frequency, yet your design changes randomly along the line from expanding to contracting taper along the way! :confused:

I don't get a lot of this stuff, maybe it will just average out to a straight line, or the simple SD/S0 ratio will be the determining factor and the changes of section along the way won't matter. I don't know, just wondering if you did!?!
 
Most of the funny looking stuff is me drawing erratically . I personally like consistency, so if i started on an angle, i will end on an angle. I hope that makes sense. And yes from what i understand now the Sd affects the tuning but not in the way i had originally read it. Its the Cross sectional area of the line. full size and smaller affects tuning by affecting the air velocity. < i think <

Hell, i am still trying to get a grip on this. I have been out of school for 17 years and now i am trying to use rusty B+ math skills on a foriegn topic.

Thankfully i have no kids so i can make mistakes and not really hurt anything other then my pride. I dont have food responsibilties :D