Slot port help

[Javaman]

I am considering building a little EBS sub which all told will end up a net box interior of a little over 1.6 cubic feet. Tuning to 25Hz and using the smallest quiet port diameter of 3 inches ends up almost 19 inches long. Hummmm?

I guess I could pretend I was a submarine pipe fitter and twist it in somehow but what about the slot port approach? This would use side of the box as part of a rectangular port something, like a transmission line.

I can't remember where but it seems I read something about the vent calculation for a slot port being different than for a round tube. This makes sense considering having a vent tube too close to a side wall apparently effects the tuning frequency and I would be using the box wall itself as one side of the vent.

Anyone have information on this?

Many thanks.

 

[Two Moons]

You are correct about the calculations being different if using a side wall as one of the port walls. Go to jlaudio.com and click on the tutorials part. There is a tutorial on slot ports with exactly what you are looking for.

Dave

 

[Javaman]

Thanks Dave - looks perfect.

The W7 looks interesting, anyone using these glitzy car audio drivers for home systems?

 

[kelticwizard]

I guess I could pretend I was a submarine pipe fitter and twist it in somehow
Many thanks.

Just thought that I would throw in the fact that elbow fittings are available, either in building supply stores or over the internet, for PVC pipe. That is another way to deal with a too-long port.

Anyway, good luck with your slotted port project.

By the way, what driver are you using that requires only 1.6 cu. ft but requires tuning down to 25 Hz?

 

[Dustin Haug]

Javaman, I'm not using W7's , but I've got a sub using 3 8W6's in a 6th order bandpass. It's mainly a music sub, but it plays deep too. In room response gets well over 120 dB during the depth charges on U571. Not bad for 3 eights and 250 watts.

 

[Dustin Haug]

Another thing you could consider is PR's although that would add some considerable expense.

 

[Javaman]

kelticwizard

The driver is the Titanic MKII 10 inch - the PE EBS alignment looks interesting with a slow simmed rolloff like a sealed box, but an anechoic F3 round 28Hz. Thought this should yield a really nice in-room response for my mostly music application - maybe a little boost @ 20-23z to take it low?

Actually I was considering this or the 12 inch driver version in a 2 foot sealed box with a more aggressive boost.

Any thoughts of the relative merits of these two approaches?

Dustin

Thought about PRs but the cost and the difficultly of tuning it just right for music turned me off from the idea.

thanks
peter