Bottlehead Forum

General Category => Technical topics => Topic started by: cmcdonnell on July 03, 2010, 05:39:20 PM

Title: High Pass Line-Level Crossover
Post by: cmcdonnell on July 03, 2010, 05:39:20 PM

I use a powered subwoofer with my full range Fostex FE168E speakers.  According to their data the impedance begins to rise below 200 hz and peaks at 50 hz at almost 70 ohms.  Is there a simple line-level crossover that will roll off the frequency below 200 hz with minimal sound degradation and hopefully allow my Paramours to push a little harder?

Chuck

Title: Re: High Pass Line-Level Crossover
Post by: Paul Birkeland on July 04, 2010, 08:38:12 AM

You can decrease the value of the .1uf coupling cap in the paramour.  Pick the -3db frequency you would like, then C=1/(2*Pi*R*F) where R is the grid resistor in ohms (usually 249,000), F is the frequency you picked, and C is the coupling cap value in Farads. 

Title: Re: High Pass Line-Level Crossover
Post by: cmcdonnell on July 04, 2010, 11:20:02 AM

Pi is 3.14?

Title: Re: High Pass Line-Level Crossover
Post by: InfernoSTi on July 04, 2010, 12:39:59 PM

Quote from: cmcdonnell on July 04, 2010, 11:20:02 AM

Pi is 3.14?

Yes, you are correct: 3.141593

Title: Re: High Pass Line-Level Crossover
Post by: Grainger49 on July 04, 2010, 12:54:25 PM

Not that you can buy a capacitor to three, much less seven, places.  But you will get a very accurate calculation.

Title: Re: High Pass Line-Level Crossover
Post by: cmcdonnell on July 04, 2010, 05:26:53 PM

Thanks for the info.  I ordered 3 different values and I will try to do some testing when they come in.  According the the calculation it comes to about .003 mf.