Home Theater Forum and Systems banner

21 - 26 of 26 Posts

·
Registered
Joined
·
38 Posts
Discussion Starter #22 (Edited)
Ok, that is what I meant. Thanks, yet again.

So WinISD is only concerned with the volume for the enclosure, not the shape, right?
Now, how come for the box setup, I'd be using 3 flared ports that have a diameter of 4", while for the tube I'd need one with a diamater of 8"? I know they're different lengths, but couldn't I just make a box with one 8" port?

EDIT: Is it because of the volume? If I had one port in the box, with a length of 20+, it would throw the volume of the box off, because it would have to fit inside it.
 

·
Premium Member
Joined
·
19,397 Posts
Yes, WinISD is only concerned with the volume for the enclosure. Tube or box, you can use three 4" ports or one 8 inch port. I originally mentioned three 4" flared ports for function and looks. I built a 12 cu. ft. box with three 4" flared ports. See here:

http://www.hometheatershack.com/forums/ported-subwoofer-build-projects/8554-mach-5-audio-ixl-18-4-build.html

Is it because of the volume? If I had one port in the box, with a length of 20+, it would throw the volume of the box off, because it would have to fit inside it
The displacement of whatever port you would use has to be accounted for in the design, you add the displacement of the porting, sub and bracing to the 12 cu.ft. net volume that you need for the sub to get the total internal volume needed for the box.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #24
Cool.

So why did you decide to have flared ports that bend 90 degrees (elbow joint?)?
Also, your bracing inside looks more involved than I had imagined, how come?

How come some builds (ex: Quartet10 kit) use radiators, while others use ports? Is it because radiators are better suited to smaller drivers?

I think after all this, I just have to decide on a design then start working out the total internal volume.

PS -- in your WinISD screenshot above, where you showed me the graph for MJ-18M, how did you get your graph to look like that? Mine doesn't, it has a little "hump" at 20Hz.
 

·
Premium Member
Joined
·
19,397 Posts
My ports have elbows as they were too long to fit. For best results the ports should be one diameter away from any cabinet wall.

Smaller sub cabinets that are tuned low require long ports. After a certain port length the first port resonance frequency becomes an issue. PR's eliminate the first port resonance and take up less room in the sub.

You have a hump in your graph because you didn't add the Hi-Pass filter that the amp has.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #26
You should start a wiki on this.

Thank you very much for your help.

My next step is to decide what kind of sub I want and how it will look. Then I'll probably be back here asking more questions, once I decide on parts. Hopefully creativesounds answers soon!

Thanks again for all of your help.
 
21 - 26 of 26 Posts
Top