how low could the FF85 be crossed


2007-12-05 10:39 am
If the output needed is just in the mid 80 dB, so just say 2 watts are run into them; and the XO is 4th order, how low could the FF85 be crossed?

I'm going to use them as effectively near field in a 2.1 setup, so the lower the XO the better
I wouldn't mind since they would move little volume of air.
Just make some little boxes with many holes in the back ( same as Sd in total)
The speaker would have sufficient damping from internal volume above Fs and below,
the hole(s) makes the speaker see an open box. So the diameter of the hole(s) could
even be chosen for tuning at Fc.
> the hole(s) makes the speaker see an open box

the hole -one- needs to be acoustically treated; and the box medium density stuffed.
Acoustically treated means a grill or better a cloth - felt would be the optimum- with sufficient space (s) to let the air travel freely.
as the purpose is not to tune in the very strict meaning of the term ( as for find the right dampening of the cone trough TS parameters ) but to dampen...
well...of course Qts would be about 1 when right done :cool:


2007-12-05 10:39 am
Interesting – so it’s like a sealed box, with the Q lifted to 1 – quite high

What might the resonant frequency be, about the same, as for a sealed box of the same size, with the resonant frequency about the same?

Is there a name or web link for this technique?



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