[SteveRB]

this post could be sub-titled -- the math is killing me.

My project idea:

i just received two very nice Altec 604-k's. I have looked into the traditional enclosures and the updated Stonehenge boxes. After further research, I would like to build a Mass Loaded Transmission Line (MLTL) enclosure for them. I have read the 6 moons review of the following:

http://www.6moons.com/audioreviews/altec/dream.html

However, i believe that i would like the enclosure front baffle to be more similar to the classic Altec 620:

http://www.wardsweb.org/audio/Altec/Altec77.html

My ideal situation is a bottom or front firing enclosure that is wide, shallow, and tall. I am able to accommodate a volumes above 9, 10, or 12 ft. cu.

I see that Martin King has removed his MathCad worksheets from his website. I have been working with his 'Classic Transmission Line Enclosure Alignment Tables'; however, my inexperience is really frustrating, and the math is killing me.

I have had great help before through Audio Circle. And, i would really appreciate a little mentoring to get through the first design stages. I am certainly willing to document my process for other people's DIY projects. I have professional 2D and 3D drafting capabilities to ensure proper plan details and reference material.

Anybody out there willing to join my team?

[SteveRB]

or is this a non-starter...

[JoshK]

I can't be much help.  I could help on math if I understood the problem.  I was looking to learn about TL loadings but also came to brick wall when I realized that MK removed his spreadsheets.  I asked if he still shared on a case by case basis and the answer was no. 

I think there are other spreadsheets out there, but haven't looked into it.  It is further down my priority list of things to do. 

I *think* if you have a design you are trying to copy but wanted to change the aesthetics of, you can keep the cross-sectional area of the taper constant across the lenght.  So if you want to make it wider and shallower, just make sure the width x the depth of the cross section is the same as before.  You should be ok.  If I am wrong because there is something unique about this loading, hopefully someone will speak up.

[SteveRB]

thanks for the fast reply. Problem is, i have found no real precedence for me to copy. All enclosures are just variations on a vented box.

i can get through the equations on the Alignment Tables; however, im unsure of the starting point. what is the basis for choosing a frequency to tuning the pipe? Should i start at the driver's Fs or +/- 10 Hz?

my first calculations gave me and enclosure of 20 ft cu.  that's a little too big (even for a bachelor-pad like mine)...

[JoshK]

Questions I don't know the answer to.  Ones I'd like to learn about as well.

[planet10]

Do you have accurate T/s parameters?

The MJK tables will only get you a classic TL. An ML-TL should be shorter.

dave

[SteveRB]

my Thiele and Small info is from:

http://www.thielesmall.com/include/details.asp?ID=41&dtype=1

Question: Are the tables meant to produce the enclosure's length and surface area at the ends?

example - a straight pipe (SO=SL):  i calculate a length of 89" by a SO of 385 in. sq. thus resulting in a volume of 20 ft. cu.


is this the correct use of the tables?