Harry Hietbrink (harrynliz@slingshot.co.nz) provided the following brief description of his transmission line speakers:
 
Tunnel length of 2.7 mtrs starting at 1.25 sd and terminating at .975 sd
separate Mid / Hi enclosure of 8.6 cu ltrs
all internal surfaces painted with bituminous automotive sound deadener (body schutz)
coupling braces behind bass and mid drivers
stuffed with long fibre wool at 1/2 lb per cu ft and 3/4 lb per cu ft in the mid encl.
all drivers damped with" blu tack"
internally wired with monster cable
re-built and modified DN 12 crossovers externally mounted and bi wired .
total weight 48 kg.
 
They sound absolutely fantastic bar a slight scratching in one of theT27s when pushed so I am sourcing another pair of these.
A special thanks to Colin R and Ian T for there input, both of their suggestions were put to use in the design.