• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Any good explanation of Passive EQ Filters??


2007-02-11 1:04 pm
I have been building electronics since I was a kid. I've learned a good deal of tube audio. But I know very little about Filters (EQing). I studied EE in College and have a Bachelors therein but I know only the basics in Filters.

Are there any good references on tone-stacks? I understand Fender guitar amp EQ to a certain extent but definitely could know more. Is there anything out there that really explains things. Or could help aid in EQ structure design?
If you are an EE then you just need to go back to the books to refresh....it's all there..
You basically should be able to go back and forth between BODE plots and deriving the transfer function and then extracting your POLES and ZEROES ..... These POLES and ZEROES are applied to a filter circuit...
If you need adjustable filtering, then you calculate for variable R , using potentiometers..

You can think of passive filtering as frequency dependent voltage dividers, if thats any help.....

Another key thing to keep in mind when designing filters, is knowing your source impedance as well as you loading impedance..this should be included in your transfer function analysis.....