Author Topic: Creating custom bands in an EQ pedal?  (Read 882 times)

thesameage

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Creating custom bands in an EQ pedal?
« on: January 17, 2017, 04:52:35 PM »
Hey all,

So, I'm trying to wrap my head around this. If anyone can help point me in the right direction it would be appreciated. So, I want to create a bass EQ pedal that uses 5 custom bands based on popular bass preamps.

I have a 1776 effects six shooter board and on the BOM, it says to use http://www.muzique.com/lab/gyrator.htm to figure out how to create custom frequency bands. To do this, though, you have to enter the values of 2 caps and 2 resistors and then it will calculate the frequency. However, I have no idea how to determine the value of the caps and resistors, just the final frequencies that I want. How do I go about figuring this one out?

This is what I'm looking at:
40hz Bass
4khz Treble
500hz Mids
1 khz Low Mids
2.8khz Hi Mids

diablochris6

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Re: Creating custom bands in an EQ pedal?
« Reply #1 on: January 17, 2017, 06:47:13 PM »
I once built a Tubescreamer with gyrators to control bass, mids, and highs. I used the same site you posted, and I believe I used the various values listed in this post http://tagboardeffects.blogspot.com/2014/05/4-band-gyrator-eq.html?m=1 as a starting point and tweaked them to get the values I wanted. Hope this helps a little.
Build guides of my original designs and modifications here

stecykmi

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Re: Creating custom bands in an EQ pedal?
« Reply #2 on: January 17, 2017, 07:05:08 PM »
a simple but a time consuming way to do it would be to enter the stock values as per the six shooter build doc into the calculator and tweak the values until you get what you want (that's how I would do it).

in general, increasing any of R1, R2, C1 or C2 will lower the filter frequency. However, you should also take note of the filter Q, which is basically how "wide" the filter is. There is no correct value but it should be between maybe 2 to 4.

also looking at your chosen notch frequencies, you have a very wide gap between your lowest and next lowest frequency. This means you will have no control over the frequencies between say 80hz to 250hz.

thesameage

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Re: Creating custom bands in an EQ pedal?
« Reply #3 on: January 18, 2017, 11:30:42 PM »
Thank you! I have to get a better understanding of the frequencies here. THe bass and treble are the sadowsky values and then I just copied the mid values from the darkglass pre. Maybe not the best combo!