Vented Enclosures

[tige']

Thanks Phil, thats great advice.

What about slotted ports versus round ports. Any advantages / disadvantages there?

What about material for ports? I have seen some info about flanged tubes for round ports. It looks like these are better than just a straight tube?

For slotted ports would you just use the same material as the enclosure? Is there any way or reason to "flange" the end of a slotted port? (ie. have it terminate at an angle)

Thanks!!

[philwsailz]

Thanks Phil, thats great advice.

What about slotted ports versus round ports. Any advantages / disadvantages there?

What about material for ports? I have seen some info about flanged tubes for round ports. It looks like these are better than just a straight tube?

For slotted ports would you just use the same material as the enclosure? Is there any way or reason to "flange" the end of a slotted port? (ie. have it terminate at an angle)

Thanks!!

Slots can look a lot cooler than the end of a round PVC tube showing at the face of a box. In certain instance they are easier, since they can be constructed from same or similar material as the box is built in. Using an exterior enclosure wall is very common. Acoustically there is no major advantage either way.


Flanges are good, as they remove sharp edges and provide a transition between the tube and the open air. Sharp edges are location where we can accidentally create noise due to turbulance. they also look cool. There are several ways to create the flanges, either with a ready-made port termination system which has the flange injection-molded for both the inside and the outside of the rould port, or you can use a round-over bit in a router if you are doing a slot port.

While we are at it, and talking about sharp edges... Slot ports that turn corners inside of enclosures have sharp edges, at the 90-degree junction(s). Most of the time you will not find a pre-fab box with any rounded edges or fillets in the corners, but if you are building on your own it is a nice touch, and can make the enclosure less prone to port noise/distortion.

Just like folks polish and tweak intake and exhaust runners and plenums on performance motors to smooth and improve airflow, we can do the same with an enclosure's port to improve its performance. If you think in terms of that analogy, you can probably understand and visualize how to improve upon your own port design...

[Timmy!]

After a quick check on the specs for that woofer...

We can use a vented enclosure that has a gross volume of between 2 and 2.25 cubic feet. With gross volume specified here, I have already compensated for an approximate volume displacement for the woofer and the port, (which is usually inside the box). So if you care to actually calculate now much the woofer and the port displace, you will find that nets us to around 1.75 cubic feet for an effective box volume.

There are a couple of ways to do the port. a 6" diameter, (inside diameter) port at 20" length will work quite well. If you cannot find 20" in length for the port, we can go a little smaller on the diameter and shorten the port to compensate. We just do not want to get the port diameter too small or it will start to get way too noisy..

If you want to construct a slot port, you can use one that is made of wood with inside dimensions at 2.5 x 10.5, (10.5 is convenient as it is about the same as the OD of the woofer so it will look nice), or at some other combination of dimensons that gives a similar araea, roughly 262.5 sq. in. A slot port will sound the same as a round port; don't let anyone sway you otherwise....

Howzat?

Ok, almost time to build my box. I can build the slot port similar to this one, right?

[philwsailz]

Timmy hangs out on Wakeworld...

Yeah, I recall seeing that pic and thinking it dod a good job of explaining how to build a slot in during box construction...

In this pic, you can see that the builder has taken the extra steps to add 45-deg. chamfer corners to the turns in the port. This helps make the port quieter; makes more music and less noise due to turbulence...

Go for it TImmy!!!

Phil

[Timmy!]

Sweet! I will hopefully be building it in 2 weeks! I have some challenges though since the heater is in the same compartment but I think I can get it. I will of course take lots of pics