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-   -   Do I really require this box volume? (http://www.diyaudio.com/forums/multi-way/132481-do-i-really-require-box-volume.html)

rhythmdiy 3rd November 2008 03:37 PM

Do I really require this box volume?
 
I recently bought a pair of Vifa PL26W
when I tried using WinISD beta I got 3.75cuft of volume for the box ( ported ) But I rarely see any speakers using such a volume for the woofer in a 3 way system.. can anybody tell me why should I go with such higher volume?

BHTX 3rd November 2008 03:45 PM

Large VAS? (over 100 liters at least, IIRC)

rhythmdiy 3rd November 2008 04:30 PM

yeah it has
Vas 110 ltrs

Undefinition 3rd November 2008 05:32 PM

Re: Do I really require this box volume?
 
Quote:

Originally posted by rhythmdiy
I recently bought a pair of Vifa PL26W
when I tried using WinISD beta I got 3.75cuft of volume for the box ( ported ) But I rarely see any speakers using such a volume for the woofer in a 3 way system.. can anybody tell me why should I go with such higher volume?

Here's a trick I use often:
1. Try taking the "optimal" enclosure volume that winISD/Unibox/whatever tells you, then halving it, or only 2/3 or 3/4 of it... plug that smaller cabinet into your program.
2. Tweak the box tuning until you get a satisfying roll off.
3. Now, compare the F3 of your "fractional" enclosure to the "optimal" enclosure.
If the optimal enclosure has an F3 that's only a few Hz lower than your fractional one, then it's not worth it for those few extra Hz. Plus, with a smaller enclosure comes less group delay. Less space, tighter bass; it's win-win.

Example:
For the Sunflowers, I used the Dayton RS225, which says the optimal box is something like 75 Liters w/ an F3 @ 27 Hz. I built a 40 Liter cabinet (and adjusted the tuning to get a roll off I liked), and the F3 was 32 Hz. It just didn't seem sensible to me to build a box twice the size for 5 more Hz. Plus, as I said before, the transient response is tightened up over the larger cabinet (well, in simulation, anyway)

crazyhub 3rd November 2008 08:00 PM

You don't need to go as large; for example, in 60 liters you get f-3 = 36Hz

http://img369.imageshack.us/img369/517/vifapl26wkg4.png
http://img369.imageshack.us/img369/v...png/1/w800.png

Godzilla 3rd November 2008 10:28 PM

>>> If the optimal enclosure has an F3 that's only a few Hz lower than your fractional one, then it's not worth it for those few extra Hz.

I agree and do this all the time. But i have built cabs that were too small. So I usually see how big WinISD wants the cab and go as small as I want the cab and work my way up.

rhythmdiy 4th November 2008 04:25 AM

thanks alot friends...


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