high pass filter for woofer in bass cabinet

[timmiller]

The background: I'm putting a 15" woofer and a tweeter into a 1.75 cubic foot sealed cabinet for bass fiddle amplification. I've picked 1600 Hz for the 1st order crossover point, and that seems to require a capacitor of 12.4 uf for the tweeter and a .8 mH inductor for the woofer.

Manufacturer docs recommend putting a 20 hz high pass filter in to prevent woofer over excursion. Should that be a 1000 uf capacitor? If so, does it go in series with the inductor?

Please help. Thanks much.
-Tim
Eugene, Oregon

[zach_t]

Provided Link: http://ccs.exl.info/calc_cr.html#first


> Manufacturer docs recommend putting a 20 hz
> high pass filter in to prevent woofer over
> excursion. Should that be a 1000 uf
> capacitor? If so, does it go in series with
> the inductor?

A 1st-Order high-pass would be a capacitor in series with the woofer.

Here is an online calcultor. Just remember, you are looking for a high-pass, so take the value of the capacitor from the tweeter.

[billfitzmaurice]

> I've picked 1600 Hz for the
> 1st order crossover point, and that seems to
> require a capacitor of 12.4 uf for the
> tweeter and a .8 mH inductor for the woofer.

I wouldn't use anything less than a 3rd order HP filter.

> Manufacturer docs recommend putting a 20 hz
> high pass filter in to prevent woofer over
> excursion.

That would be an electronic high-pass filter, contained within the amplification chain. As far as frequency goes a 20 Hz filter would serve no purpose with a pro-sound driver; even with kilowatt rated pro-sound subs 30 to 35 Hz is the norm.

Based on the content of your post my guess is that you're not an experienced speaker designer/builder and that you're not working with a tried and tested design. You should condsider doing so.

[unknownuser]

You would only use a high pass filter on a big woofer in order to get it to accpet huge volumes of sound, and live up to it's demanding specs in a pro sound PA system environment, like if you were using it in a wall of sound or something. You don't need it for your application. Depends on the music type and amp.


(Originally posted by: BFB)