DIY Subwoofers - General Discussion

**JoeESP9** · **07-28-09, 03:54 PM**

Is there a formula for determining how much a given amount of stuffing changes the effective length of a TL.

ie: 1 pound of stuffing in a 12" diameter 6.5 foot tube increases the effective length by now much?

**GPM** · **08-01-09, 04:59 PM**

No simple one AFAIK, but maybe you can figure out a rule-of-thumb from these experiments. Note that it will apply to only fiberfill since each type of stuffing will have different physical properties, otherwise best to invest in MJK's MathCad worksheets for TL, etc. designs and use Polyfil: http://web.archive.org/web/20021007065602/http://integra.cyberglobe.net/caraudio/resources/fiberfill/

GM

**JoeESP9** · **08-01-09, 08:07 PM**

Thanks! Thats someplace to start.

**GPM** · **08-01-09, 09:41 PM**

You're welcome! Hope you share if you have any luck with it.

GM

**JoeESP9** · **08-02-09, 11:25 PM**

Of course I'll share. I thought that was one of the reasons for this site. It may take a while because I'm still sorting this out. So please be patient.

**GPM** · **08-03-09, 10:07 AM**

It is, but the sad fact is that it's been my long time experience that the majority of folks who join forums only do so to 'pick brains' and move on, so just wanted you to know I was interested in any results since I didn't succeed in my attempt WRT 1" acoustic fiberglass insulation, but then I didn't have access to any affordable measuring tools beyond a DIY kit signal generator and o'scope when I tried decades ago.

Understood...........

GM

**JoeESP9** · **08-15-09, 12:43 PM**

Thanks again. Been busy so I couldn't respond. Also wanted to make sure no one thought I was cherry picking.

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