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DIY 1st order highpass filter values?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author DIY 1st order highpass filter values?
Johnbomb
Search is down, so sorry if this has been covered. Can anyone suggest capacitor/resistor values for a 1st order highpass filter with a corner of 200hz for Eurorack? I'm not sure how to deal with modular impedance levels.

Thanks,
John
cackland
This is the formula to calculate the cutoff point:



For a 10K impedance, a 75nF capacitor should give you 212.21Hz
For a 10K impedance, a 82nF capacitor should give you 194.09Hz

These capacitor values are the closest I've found.

An ideal capacitor for 200Hz would be 79.57nF, which does not exist.
Johnbomb
Much appreciated, cackland! I assume the non-inverting unity amplifier represents a generic module?

Thanks,
John
cackland
Correct. If you need to add gain / increase the dampening factor, you can add two resistors from the inverting terminal to ground.



Check out this article, it explains it well. There is a whole bunch of information on this site.

https://www.electronics-tutorials.ws/filter/filter_6.html
Grumble
check out this site: http://sim.okawa-denshi.jp/en/

choose one of the sub-pages like for filters use http://sim.okawa-denshi.jp/en/Fkeisan.htm

fill in the values of the used components and the program will calculate diagrams etc.
Johnbomb
Thanks very much, guys. I'll report back with results.
Johnbomb
Success! A little background: I needed to high pass filter drum audio going into a Bard Ivan phosphor drive distortion unit (super cool!) in order to shape the sound a bit, especially on the kick.

Previously, I had been doing this with. a 2hp MMF filter, but I thought that was a huge waste for such a versatile unit. 200Hz high pass was about where I was when I measured white noise through this module, so that's what I was shooting for.

I had a ceramic capacitor kit that went down to .1uf, and a variety of resistors. With a single series .1uf cap (C in the first pic) and a 10K resistor following in parallel (R), I got around 350Hz high pass. Ultimately, I settled on just the .1uf cap- it cleaned up the kick just enough, somewhere a little over a 100Hz corner (best guess based on watching white noise:)

Once again, thanks!
John
cackland
Nice Guinness ftw!
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