Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Is oscillation bad for an active audio filter?

audioguru

Well-Known Member
Most Helpful Member
A Butterworth filter has a flat response to near the corner frequency then a sharp corner that you want.
A Bessel begins dropping its response far from the corner frequency causing a droopy response and a gradual corner that you do not want.

To make a "perfect" Butterworth filter with a gain of 1, put two of the same same capacitors for a lowpass or two of the same resistors in parallel for a highpass in parallel since many values are not exactly doubles.
 

LvW

New Member
Let me see if I get this straight, the big difference from Bessel & Butterworth are mainly dependent on the ratios of the caps or resistors in the feedback loop vs ground? A ratio of 2:1 or better is Butterworth, less is Bessel? Then what is a sub-Bessel?
Super-Dave, you should try to become somewhat familiar with a very important filter parameter: Pole-Q.
This parameter desrcibes the position of the second-order pole pair in th s-domain - and it has a very direct relation to the magnitude and phase response of the filter.
This parameter (pole-Q) is the only one which numerically characterizes the various response alternatives for a second-order filter ("lowpass approximations" to an ideal "brickwall" lowpass response).

Examples: Critical damping (Q=0.5), Bessel (Q=0.5773), Butterworth (Q=0.7071), , Chebyshev (0.9565 for 1dB ripple),
 

Latest threads

New Articles From Microcontroller Tips

Top