I think we are all learning a lot from this discussion. Esp. since TQWT seems to be so favored by DIYers.

BTW, my impression is that these harmonics may not matter, except in the raw Voigt pipe, where the dip is pretty bad. The frequency curves in the fostex & Lowther drivers (the F200A I suppose being an exception, and the FE166/Fe167 also I suppose) is so raggedy that a few db here and there are not that big a deal. THe raw voigt pipe does look pretty bad though.

Let me clarfiy what you are saying for my own benefit.
I guess you are saying, if a Voigt pipe is tuned to, say, 40 HZ, then the F0 = 40 Hz, and the F2, which is 160 Hz is not well suppressed.
What does that mean: not well suppressed? Does it mean that there is a tendency for there to be a peak there, becuase of the box, and this peak is not well suppressed? Whereas in a non tapered QWT, the 160 HZ is better suppressed?
I guess I am confused becuase the math cad model shows a dip for the Voigt pipe, whereas the argument is that it will have excessive peaks.
In general, are we saying that the TQWT (hat we are loosely calling a voigt pipe here) produces more of a comb effect than a Non Tapered qwt?
thanks
-akhilesh