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<blockquote data-quote="Volenti" data-source="post: 6037565" data-attributes="member: 566487">First off, polyfill doesn&#039;t really effect T-lines like that, it will damp the line and this effects higher frequencies more than lower ones, so when you listen to the line before and after, the &quot;after&quot; sounds like it&#039;s going lower than the &quot;before&quot;, when it&#039;s really just filtering out the higher frequencis more.Not that it can&#039;t be used to good effect though, and I often partially stuff lines that have to be made &quot;too small&quot; to fit in the vehicle, it just won&#039;t lower the tuning frequency by any meaningfull amount. (essentially I can make a small line have a similar response to a larger line with carefull design and stuffing, but the large line will have far greater output)Now, design, all though tapered lines are harder to fold and build, they are the most forgiving acoustically.Try this, get the sub/s you intend to use, measure the cone area, make the start of the line (where the subs are) 1.5 x total cone area, make the total line length 70&#039;&#039;- 80&#039;&#039;, make the open end of the line 0.7 x line area.That will give you a pretty balanced response with a majority of the subs on the market, especially high power/stiff suspension (spl ect) subs, anything that&#039;s normally designed to handle abuse in a ported box.I make &quot;cash&#039;n&#039;carry&quot; enclosures based on those ratios, if you want more punch, make it shorter, if you want a lower response, make it longer, simple //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif</blockquote>

[QUOTE="Volenti, post: 6037565, member: 566487"] First off, polyfill doesn't really effect T-lines like that, it will damp the line and this effects higher frequencies more than lower ones, so when you listen to the line before and after, the "after" sounds like it's going lower than the "before", when it's really just filtering out the higher frequencis more. Not that it can't be used to good effect though, and I often partially stuff lines that have to be made "too small" to fit in the vehicle, it just won't lower the tuning frequency by any meaningfull amount. (essentially I can make a small line have a similar response to a larger line with carefull design and stuffing, but the large line will have far greater output) Now, design, all though tapered lines are harder to fold and build, they are the most forgiving acoustically. Try this, get the sub/s you intend to use, measure the cone area, make the start of the line (where the subs are) 1.5 x total cone area, make the total line length 70''- 80'', make the open end of the line 0.7 x line area. That will give you a pretty balanced response with a majority of the subs on the market, especially high power/stiff suspension (spl ect) subs, anything that's normally designed to handle abuse in a ported box. I make "cash'n'carry" enclosures based on those ratios, if you want more punch, make it shorter, if you want a lower response, make it longer, simple [IMG]//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/IMG] [/QUOTE]

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