Anybody ever build a Subsonic (highpass) filter?

[TheOtherSide 10+ year member]

I need one for my amp...I am going to be porting my driver here soon and noticed my amp doesn't have an onboard subsonic filter. I was going to design/build a passive filter to accomplish this same feat though. Just looking to see if anyone's done it and how easy the parts are to come by (PartsExpress has em just want to see if I can get them local).

Probably build a 12 dB highpass 20Hz inline RCA filter to use before the signal reaches the amp.

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[kross 10+ year member]

You can't create a passive filter without knowing the impedance of the load, which in this case would be the amplifier. Do you know the input impedance of the amp? If so, you just need a capacitor and a coil to make a 2nd order HPF.

Capacitor value (in farads) = 1 / (2 * pi * freq * impedance)

Inductor value (in henries) = impedance / (2 * pi * freq)

Put capacitor in series, coil in parallel.

 

[dyohn 10+ year member]

http://store.hlabs.com/pk4/store.pl?section=12