Focal 4K2 enclosure

[karelch]

Hello there, this is my first post concerning a tower speaker I'm currently building. I have a Focal polykevlar kit and my question is about the mid 4'' (4K2).

Fs. 54.41 Hz
VAS 5.51 L
Qts 0.243
Qes 0.25

In a sealed box, the speaker calculator gives me a result of .74 L. driver displacement of 0.22 L. that would give me almost 1L for a speaker box. This seems really small and an odd value since the 6.5'' inch needs 55 L of space. I would like to have your thoughts on this before everything is glued and screwed together.

Note: This is my first DIY and normally I speak french so sorry if there are mistakes.

[Inductor]

Should be fine if you simulate with other Focal 4" drivers (0.6 to 1 L) and giving F3 about (or over 160Hz to) 200Hz.

[karelch]

Thanks

[bbggg]

If you plan to use the driver as a true mid, ie crossed way above its resonance band, you don't really need to use T/S calculations at all. Its chamber will only serve as acoustic isolation, therefore you can design it as best as you can so as to avoid reflections and absorb stray echoes. T/S is relevant only with regard to a driver's fundamental resonance when used as a high pass filter.

[karelch]

Originally Posted by bbggg

If you plan to use the driver as a true mid, ie crossed way above its resonance band, you don't really need to use T/S calculations at all. Its chamber will only serve as acoustic isolation, therefore you can design it as best as you can so as to avoid reflections and absorb stray echoes. T/S is relevant only with regard to a driver's fundamental resonance when used as a high pass filter.

That would simplify my design.

According to T/S calculations, my 6,5'' driver should be in a ported enclosure. Is it absolutely necessary ? Could it damage the driver if it's in a sealed enclosure ?

[bbggg]

No, but it would probably not play as loudly in the low end of the spectrum. The software you use will probably give you some ballpark figures of LF driver displacement and power requirements under both scenarios.