Line Length of a ML-TQWT

[chairforce]

Hello Forumites

I would like to build a ML-TQWT cabinet for the Alpair 10, similar to Cyburgs Needle. I am still reading about that type of enclosure, trying to understand the underlying physics.

I wonder if there is a method of calculating the length of middle line of the cabinet. So far I have not found any information about the math of that most important parameter of a ML-TQWT.

The Alignment Tables of Mr. King may be a first start to look at, but I am not sure if I can use that information.
The effective length of a tube (tuned to 45 Hz, SL/So=3) would be 232 cm (91.4 inches), but that length only applies to a tube with an open end. The terminus of my project, that has the properties of a Helmholtz Resonator, seems to act as an additional acoustic impedance that reduces the effective line length.

At this point I do not know how to proceed. Should I use the unsatisfactory rule of the thumb L=c/(4*f), in the hope that the too short line length is compensated by the acoustic impedance of the port?

Or are there any Alignment Tables for ML-TQWTs?

Thank you for your help!

[Zen Mod]

contact MJK and buy his sheets

25$ is bargain

then you can read/participate in QW Yahoo group , where MJK is regular

[chrisb]

Originally Posted by Zen Mod

contact MJK and buy his sheets

25$ is bargain

then you can read/participate in QW Yahoo group , where MJK is regular

indeed, far less than the (real) cost of a few hours of sweat equity, brain strain, and wasted materials if the first iterations built on "classic" understanding of ROT don't quite work out


maybe Martin should charge $125