Vented box design question


2001-02-19 10:38 pm
Some people say that sealed = best sound quality
Others say vented designed correctly can almost = sealed
when it comes to sound quality.

Is there a correlation between port diameter and sound
quality - heh

Example, would dual 4" diameter ports sound better/worse
than a single 6" diameter port when working with a single
15" woofer powered by a 500w - 1000w amplfier ?

What would you chose for best SQ.
Well I think that this is a loaded answer. Loaded in the way that a properly vented enclosure can sound very very good. One of the major problems/downfalls with vented enclosures (over sealed) is less power handling. The plus is greater cooling for the voice coil as aposed to the sealed. As far as to which sounds better...well that really depends on your taste. What I personaly like about vented enclosures is the fact of tuning them to a spec. frequency. Does it "sound better" than some cases yes. Only if the driver/enclosure is designed and implemented properly. But....sealed enclosures have a very good quaility to themselfs. Especially when used with big power. The only problem, I find is that the sealed enclosure seems to be larger than "normal" in size to get the response I want. So why not build a vented and take advantage of the effieciency.

Ooops, forgot...yes the vent size does matter! Too small and you will get a high Vent Velocity...major noise! Too big, of a port/vent not really, but there is a ratio of Vent to Surface to Cone Coa. just can't remember it right now.

Rino Odorico
In general, maximizing the cross-sectional area of the port will lead to lower airspeed (more laminar airflow in the vent -- less turbulence), and better sound quality. A single 6" vent will give you slightly more cross-sectional area than dual 4" vents, and will be superior as a result (while needing a slightly longer length to achieve the same Fb)

Also, the single 6" vent has the benefit of having far less surface area than the dual 4" ones - reduced surface area leads to less resistive losses in the port, and will result in your driver/box system performing closer to simulations/models in real life.

The only real reason to go for dual 4" ports in my opinion is the lack of flared 6" ports for any reasonable price, and perhaps aesthetics, depending on your taste.