Bass reflex theory: multiple ports Qp

[TG]

Hello everybody!

Let's assume that we have single-port bass-reflex enclosure with known Vas, Fb, Sport, Lport (therefore we can calculate port quality Qp).

Then we substitute initial port with N equal smaller ports with the same length Lp and with Sport/N area (each). Fb of such an enclosure will stay the same, of course (let's not consider edge effects now).

The question is:
What will be "new" Q'p?
N*Qp? (N^2)*Qp? Something more complex?

Thanks in advance!

[richie00boy]

I would imagine that the new Qp would be very slightly higher than original, and the 'scale factor' depends on how many smaller ports you use.

[Ron E]

Port Q depends on more than just area, it is also drive level dependant.

Best Port Q should be with a single port vs multiple ports of the same area/length because a single port has the smallest surface/ volume ratio.

What is the goal of this exercise, the point to the question?

[AndrewT]

Hi,
knowing that a small tube has more resistance to air flow than a big tube then extrapolating to a number of small tubes of equal area to a big tube. I would expect that the air resistance for equal area would be higher for a group of small tubes.
This would imply that Qp would be lower.
This fits Ron's comment;-

single port has the smallest surface/ volume ratio.

On that basis neither formula, that you have offered, can be correct.
Sorry, keep asking.