I recently purchased a pair of Jordan’s JX-92s full range drivers for use an a transmission line project. I have constructed two different boxes to date, that were designed using Augspurger’s alignment tables and stuffing guidelines. I am really pleased with the sound of the Jordans, especially after playing them for a few hundred hours.
I am planning to build a third project, using the TLb as a guide and need a little advice scaling it for the 92s.
I have studied the TLb portion of http://www.t-linespeakers.org/projects/tlB/index.html and think I generally understand the concepts presented there, but I am having a little trouble understanding the author’s derivation of line length and box volume, especially as it relates to using the 92s in a similar design.
It appears that the TLb author’s derivation of volume could have been started as the calculation of a critically damped sealed enclosure for the Vifas. The line length seems to be based upon the requirement for a specific volume and density of fibrous material that could predictably produce a reduction in rear wave air speed in 3 feet, rather using a full quarter wavelength of line to do so. I suppose it is also possible that the author just wanted a loudspeaker that was a meter high and adjusted material, density and volume to do so.
Looking at the specifications for the Jordan JX-92s and the Vifa P13WH-00-08, reveals some striking similarities. Given that the Jordan is built by Vifa on their 5” platform it is not a complete surprise. However, the two specifications that are quite dissimilar are Fs and Vas.
Would it be reasonable to assume that using a pair of 92s drivers in the same box configuration as the TLb, stuffed with a more acoustically resistive material, such as Miraflex would work? The author notes in http://www.t-linespeakers.org/projects/tlB/appendix/density/dense_Fig2L.gif that 54” is the shortest length that can be used for the TLb, aiming for an F2 figure somewhere around Fs (45Hz). Since 54” is a little tall, could the drivers be mounted some distance from the closed end, rather than at the closed end? And if so would it be wise to use the 1/5 line length figure that Augspurger recommends, or could 1/3 of the line length be used effectively?
Dana
I am planning to build a third project, using the TLb as a guide and need a little advice scaling it for the 92s.
I have studied the TLb portion of http://www.t-linespeakers.org/projects/tlB/index.html and think I generally understand the concepts presented there, but I am having a little trouble understanding the author’s derivation of line length and box volume, especially as it relates to using the 92s in a similar design.
It appears that the TLb author’s derivation of volume could have been started as the calculation of a critically damped sealed enclosure for the Vifas. The line length seems to be based upon the requirement for a specific volume and density of fibrous material that could predictably produce a reduction in rear wave air speed in 3 feet, rather using a full quarter wavelength of line to do so. I suppose it is also possible that the author just wanted a loudspeaker that was a meter high and adjusted material, density and volume to do so.
Looking at the specifications for the Jordan JX-92s and the Vifa P13WH-00-08, reveals some striking similarities. Given that the Jordan is built by Vifa on their 5” platform it is not a complete surprise. However, the two specifications that are quite dissimilar are Fs and Vas.
Would it be reasonable to assume that using a pair of 92s drivers in the same box configuration as the TLb, stuffed with a more acoustically resistive material, such as Miraflex would work? The author notes in http://www.t-linespeakers.org/projects/tlB/appendix/density/dense_Fig2L.gif that 54” is the shortest length that can be used for the TLb, aiming for an F2 figure somewhere around Fs (45Hz). Since 54” is a little tall, could the drivers be mounted some distance from the closed end, rather than at the closed end? And if so would it be wise to use the 1/5 line length figure that Augspurger recommends, or could 1/3 of the line length be used effectively?
Dana