Please look at the enclosed VR-2 impedance curve measurements. The curve with the tall peaks is an unstuffed cabinet, basically what would be called a bass reflex design. The twin peaks, F1 and F2, are formed by two different resonance modes: the air volume of the cabinet and the air volume of the port. Impedance peaks indicate a resonance, and if the resonance can be damped, the result is cleaner sound.
Now take a look at the lower curve, which is the very same speaker but with stuffing added to convert the design to a transmission line, i.e. the stuffed pipe format shown in many textbooks on speaker design. Notice how the peaks are damped, showing the desired effect of greatly reducing the cabinet resonance and "one note bass" problem endemic to bass reflex designs.
Clearly, certain individuals on the newsgroups are confusing the labyrinth design (which may or may NOT be a transmission line depending on whether hollow or 100% filled with stuffing) and a transmission line. We have never claimed to build a labyrinth design, as we call our design a triple chamber hybrid transmission line. The three chambers are formed by blankets of thick stuffing, stapled behind the woofers; the upper woofer chamber is completely filled with Dacron, while the lower chamber behind the second woofer has 30% less stuffing density, as the exit port of the tuned pipe does not require as much damping at the exhaust end. The third chamber is the combination of the two separate chambers, now acting in unison at the vent opening.
The bottom line is the sound quality: our stuffed pipe design has tight, but deep bass response. It does NOT sound like a bass reflex design!
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