cheers.
I'm not actually sure they are Mk 3s now, as having taken the b-139 out the damping used is made of what looks to be fibreglass.
and on the Mk3 literature on the IMF site it says
"The MONITOR III is a "fourth generation" refinement of the now famous transmission line principle (first generation, the stuffed line of 1965; second generation, the tapered line of 1968; third generation, the "flow through" damping of 1969). The "fourth generation" is the development and use of "honeycomb mesh damping" (see illustration), which effectively doubles the absorption area of the filters and increases the acoustical path length"
Any ideas?
If the first generation (stuffed line) is just a tx line with fibreglass jammed inside it, what are the 2nd and 3rd gen?