If you use big power you want to have a big enough port to keep the wind from wistling. I had a pair of polk mini monitors when i was in high school, they had .75" ports. I put them on a big amp once and the wistling was so loud they were chirping to the beat. In less nasty cases I have heard the term chuffing used, and thats what it sounds like.

Hmmmm, now for my questions:

I wonder if it would be ok to use small ports with low power, as excursion, and thus air displacement is considerably less at a handfull of watts.

Can a port be too big to load the system at low power? Should port size be closely coupled to the intended rate of flow to hit a specific optimal pressure range or flow rate range? (I mean, you couldn't use a garden hose nozzle on a bottle of windex) or is it a question of just being under the threshold of audible turbulence?

Thomas

While the above is easily achieved in larger boxes tuned at frequencies > 40Hz, the opposite is the case when it comes to the now fashionable compact subwoofers with internal volumes well below 40 liters ( < 1½ cu.ft. ), & low tuning frequencies. In those cases a passive radiator is often used or alternatively the ends of a small diameter port are 'radiused' to avoid wind noises.

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