Kenwood JL-717 Ported problem (1 Viewer)

[sublinux]

Hey,
i just recently change the low frenquency (Woofer) speaker in my old JL-717 speaker. Both are amplified with a sony strde197. woofer are more powerfull than the old one. But as i can see there seem to be a problem with the ported hole. When i put big bass it seem that not all air can go out at the same time. The hole is very small.. about 2" Circle.. Is the better solution will be to make a bigger hole??

 

[Robert_J]

It's not a 'hole'. It is a Hemholtz Resonator. Determining the minimum size and proper length is easily calculated by using the formulas on this page. Also, you should be using a subsonic filter to keep the sub from playing below the enclosure's Fb.

-Robert

 

[sublinux]

The problem is that i dont got the info of the new woofer.

 

[Robert_J]

Then use a 3" port in the calculations. The port length calculator doesn't need any driver information. I would shoot for an Fb of 25hz to 20hz.

-Robert

 

[sublinux]

Fixed! I just put a port tube of 2-3/4" and its sound very better. Old hole was 1,7".

 

[Robert_J]

What is the diameter of the port? What is the net volume of the enclosure? Unless the box is huge, you still haven't tuned it low enough for home theater use.

-Robert

 

[sublinux]

The diameter of the port is 2.75 inch.

Here is my kenwood :


The port hole is at the top right in the back of the speaker.

 

[Robert_J]

And what is the length of the port? If you are just using the wood as the port, then 3/4" material would yeild an Fb of around 39hz. If your cabinet is made from 1/2" material, the Fb would be around 45hz.

-Robert

 

[sublinux]

Naa its a plastic tube of 2.75 of diamater and 2.75 length

 

[Robert_J]

Your enclosure is tuned to 30hz.

-Robert

 

[sublinux]

Sounds good no?

 

[Robert_J]

I haven't heard it so I can't answer that. What were your goals for this project? Did you meet your goals? Only you can answer that.

-Robert

 

[sublinux]

Yes, no more air noise and sub got more flex. Job done!