Cool new multi quote button!
Is there one, or are you just joking?
I'm probably just blind. I just hit reply on all of the ones that I want to quote, and it builds up in the reply box.
Is that how you do a multi-quote? I've been wondering that myself.
Paul Kittenger, right? One of those guys designed the software for that Quarter Wave Transmission line business ... Swerd told me the whole story a while ago ... there was even an analogy about mass loading. It's a cool trick if you can pull it off.
Martin J. King is the guy who made the design software for the QWT. Paul is the guy who seems to know how to use it well, and is the guy who likes to team up with people like Dennis, Jim Salk, Jeff Bagby, etc.
The mass loading analogy goes something like this:
The vibrating column of air inside a MLTL speaker cabinet is like a metal ruler clamped to the edge of a table with some overhang. A single speaker pulse gets the air in the cabinet vibrating, and a single pluck of the ruler gets it vibrating. The speaker cabinet's resonant frequency varies with the length of the column of air, and the ruler's vibration varies with the length of overhang. The longer the speaker cabinet, or the longer the overhang, the slower the vibrations.
If you clamp a weight on the overhanging end of the ruler, the vibrations get slower without making the overhang longer. Similarly, if you put a short wide port near the end of the column of air in the speaker cabinet, it slows the resonant vibrations of the cabinet. That's why M.J. King calls it a "mass loaded" transmission line.
It lets you tune a cabinet to a lower frequency without making it impractically long. King's software lets you predict how well it works with a given woofer by letting you do trial & error on the computer, rather than with lots of different size wood cabinets.