A few simple questions

[Rolex]

I'm new to DIY. So, I have a couple questions:

When calculating cabinet volume, do you need to take into account the materials you put ont he cabinet walls, or just the inside dimensions of the cabinets?

Do diver manufacturers typically call out the amount of volume the driver takes up?

I'm using this site for general info and to try and get a little info for a box.

http://www.mhsoft.nl/spk_calc.asp#ported

For the sealed portion, I'm getting weird answers. I think it's because I don't know what Qtc stands for. Regarding the specs on a driver I'm looking at, they list Qes and Qts. Can someone tell me what Qtc is, and where I would typically find that info?

Thanks for all the help!

[Brian Walter]

I'm new to DIY. So, I have a couple questions:

When calculating cabinet volume, do you need to take into account the materials you put ont he cabinet walls, or just the inside dimensions of the cabinets?

No, you don't need to subtract for open cell foam, poly fill or fiberglass.

Do diver manufacturers typically call out the amount of volume the driver takes up?

No, not generally, you can calculated it plenty close, as these calculations aren't that exact, so a little error in volume won't make too big of a difference.

I'm using this site for general info and to try and get a little info for a box.

http://www.mhsoft.nl/spk_calc.asp#ported

For the sealed portion, I'm getting weird answers. I think it's because I don't know what Qtc stands for. Regarding the specs on a driver I'm looking at, they list Qes and Qts. Can someone tell me what Qtc is, and where I would typically find that info?

First off, the sealed calculations are used if you are going to use a sealed cabinet and the ported calculation are used if you are going to use a ported cabinet, you don't use both (if you knew this already, never mind).

Qtc is a resulting Q of the driver/cabinet combination, not a driver specification. You generally target a specific Qtc for your design, something in the range of 0.5 to 1.0 is the most common. When you put a driver in a sealed box, the Qtc of the combination will always be higher than the Qts of the driver.

Finally, I highly recommend that you purch the Loudspeaker Design Cookbook and study it. It will answer most of your questions and is a very good reference to have available.

Brian Walter

[Rolex]

Thanks for the response. I intent to purchase the book you listed, just haven't had a chance yet.

In regards to ported versus sealed, I'll actually be using both. As I'm looking at a 2 1/2 way design where the lower woofer is ported, the upper woofer is a sealed enclosure.

I'm assuming that Qtc is different than Qes? If I had to enter a value for Qtc can I make an educated guess, or is there a formula I can use to determine this? That site apperently recommends .707 as a value for Qtc..

[ThomasW]

http://www.the12volt.com/caraudio/thiele.asp

The Dickason book is a bit much for the complete n00b. Probably better to start off with Speaker Building 201 by Ray Alden

[Rolex]

Thomas, thanks for the link. That was very helpful!