Question about sealed boxes.

[Dan208 23]

I'm still trying to decide what I want to do for my summer build. I want to try a multiple sub setup (3 or 4) just because I've never had more than two subs before. Anyway, I found this simple calculator:

http://www.carstereo.com/help/Articles.cfm?id=26

When I put in the parameters for the subs I'm looking at, I use the suggested Qtc of 0.707. With every sub I've tried, this gives me an enclosure volume a little larger than I'd like to use. I noticed in the "note" that you can use a Qtc of 0.9-1.2. When doing this, it brings the enclosure size down significantly.

My question is, what are the drawbacks and advantages of not using the suggested Qtc of 0.707?

[Shogen 325]

bump for answer...

[edouble101 314]

If you have winisd plot a few different qtc values and notice how the f3 point changes and frequency roll off is altered. You will also notice a peak in the f3 freq that will make the system sound boomy. Power handling will also be affected.

[Sencheezy 689]

Hmmmm..

Edited June 3, 2011 by Sencheezy

[Dan208 23]

If you have winisd plot a few different qtc values and notice how the f3 point changes and frequency roll off is altered. You will also notice a peak in the f3 freq that will make the system sound boomy. Power handling will also be affected.

I've been playing around with WinISD, but I'm a total noob with it.

[edouble101 314]

Btw although a qtc of 0.707 is ideal you can and sometimes it might be better to use a different value.

[Dan208 23]

Btw although a qtc of 0.707 is ideal you can and sometimes it might be better to use a different value.

The main thing I'm concerned with is building the wrong size box and damaging the subs. I want to keep the box as small as possible but don't want it to sound like ass.

Edited June 3, 2011 by Dan208

[95Honda 486]

A .7 Qtc is really only optimal in an environment that doesn't have a lot of cabin/room gain.

In a car, a Qtc a litle higher than .7 will normally sound pretty good due to the cabin gain of a car. Not that .7 doesn't sound good, that isn't the point here. I would just watch out if you start modeling Qtc's that approach 1. Here you will start getting some bad results....

If you make the box too small, it just won't sound so good. You won't hurt the sub though, in fact it will handle more power mechanically.

You can also add a signifigant amount of fill to lower the Qtc. You will have to experiment with this....

[edouble101 314]

This may help more, enclosure design

There are numerous online tools available. I am sure 95honda and RamDesigns will help you with a design if you ask nicely

[Dan208 23]

Thanks for the link. I want to be sure of how much space I'm going to be taking up before buying, as I'm on a pretty tight budget for this project.