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Old 24th March 2019
Gear Maniac

Originally Posted by africantigercow View Post
(Please don’t misread my tone, I am looking at this as an oppurtunity to learn something)

Is there something in speaker design that is opposite of helmholtz design? When building helmholtz resonators it is very obvious that decreasing the hole size for a given box size (and thus dropping the resonant frequency) increases the specificity of the resonance or the acoustic equivalent of ‘q’.

And obviously a bigger box will have a lower natural resonant frequency, I was talking about the port size and how much it rings in relation to the box size?

And I agree that a larger box with a larger port would be better at fortifying the bottom end but, firstly, because a bigger box has a naturally lower resonance and secondly because you wouldn’t need as much of a ‘ring’ from the ports in order to achieve an extended ‘flat frequency response’ (with a correspondingly better time domain response than a smaller box with an even proportionally smaller hole.) Hence, one could use bigger ports which ring less in a bigger cabinet?

There is also more space for bigger drivers in a big box and so you are hopefully dealing with even more low end output and even less need to fortify that bottom end?

Am I missing anything here?
It seems you're mainly missing the fact that there's a speaker with its resonant characteristics which create for a coupled resonating system. The Q factor of the port has little to do with the Q factor of the ported speaker cab. Most of the dampening forces come from the speaker, so the Q of the port usually has to be high enough. Many speaker design sims just assume a infinite port Q factor.

More pertinent port opening size considerations are about chuffing, turbulence, efficiency at loud volumes, etc.