Port position?

MisterB said:
My design and calculation are almost finished but I still have a concern. Does the position of the port really important?
I mean, does it have to be near the woofer or can it be 1 feet away..

here's my drawing...

http://dezo.cstj.net/Loudspeaker/images/imagesprojets/front.jpg

Is it ok to place it there?!

Thanks for any advice...



MisterB,

First, any port does implements some form of whistling or resonance. These are in most cases neglectable.
Here some small guidelines for port positions.
1) Make sure that the space between the backplate of the enclosure and the beginning of the port is at least 3". If this is not possible due to port length, add a curve to the port.
2) In your case the combination of a 3" port positioned away from the base speaker is the right solution. If your calculations come up with a bigger port ,say 4/6", then it would be better if you positioned the port more close to the base speaker eg. beside the speaker.
3) Did you made an airspeed check for given 3" port ? Should be below 0.2 mach. (This is the relative speed number between airspeed and speed of sound)

Hope not to confuse but help you.

Mazz.