Re: Port size on new speaker cabinets


jansb000 wrote:
> Can this process be reversed: Knowing the dimensions of the port, the
> cabinet and the thiele-small parameters of the driver and from there
> calculate the resonant frequency?

The enclosure resonant frequency is a function of the port dimensions
and the cabinet volume. That's it. So if you have a cabinet of
such-and-
such dimensions and it has port(s) of so-and-so size, that's all you
need to determine what the enclosure resonant frequency is.

However, whether that cabinet is at all suitable for any given driver
you pick is another issue altogether.

If you have a driver in hand, the parameters of the driver and a
knowledge
of what the desired system response function is supposed to be then
determines what cabinet volume is suitable and what the enclosure
resonant frequency should be. Thus, it's altogether possible to have
a driver and a cabinet and a set of ports that have no business being
put together.

> It strikes me that the cabinet design can be used for two drivers from
> FANE, namely the Colossus 12MB and the Cresendo 12MB. These
> drivers have different thiele-small parameters and therefore would
> result in different tuning of the driver/cabinet combination.

Yes, and the fact that they have different Thiele/SMall parameters
could very well mean that they need a different cabinet volume than
what you have.

Selecting the proper cabinet volume is as important a part of the
system design function as selecting the cabinet resonant frequency.
You can't just stick the driver an any cabinet and try to tune your way
to an optimum system response.

.

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