transmission line design

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I'd like to install a full range driver into a Sony SS-TL1 Transmission line speaker cabinet (pictured below).

It was a Goodwill find I couldn't resist for $30 (Audio Karma sensibility). I re-foamed the original cheap drivers and the sound is OK but unremarkable... *except for the bass performance which is amazingly extended and deep... especially considering the cheap stamped basket mid-woofer *

OK. I read enough here about TL designs to realize I don't know WTF I'm doing.
 
Dear Stalwarts & Enthusiasts,

I couldn't find anything on the internet yet (or probably i missed recognising it on Martin King's wonderful site) to resolve a few conceptual questions on QW pipe design.

* When a driver is mounted in a QW pipe (or an open-ended terminated line of any geometry), the system resonance goes lower than the driver Fs (unlike in any other enclosure). On basis of this:

1. Is it safe to assume that the effective Mms that the driver's motor "sees" is greater than that as measured in free air and mentioned in the driver datasheet?

2. If yes, would the higher Mms also lower the high frequency extension as well as the sensitivity of a wide-band driver?

3. Does it have any indication that the column of air through the line/pipe acts as a constant load against the driver cone effectively helping control its excursion? Is this air column load effective only around the 1/4 wavelength tuning frequency, or consistent throughout the whole frequency band?

4. On basis of 3. above, for a given 8" driver, let us assume two boxes - a 54 litre simple closed box and a Tapered QW pipe with the same internal volume, i.e. 54 litres (with 1/4 wavelength tuning at approx. 45 hz.) - * Would the driver gain any advantage in the QW pipe (over the simple closed box) as far as its excursion-limited power handling in the lowermost operating frequency band is concerned (i.e. 100 hz and below)?

These questions have remained unresolved in my mind for a long time. I would be greatly thankful if anybody can shed some light on this.

Thanks in advance! ��
Sujat
 
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